TODO: mark Phase 15 complete — B-003 mid-turn compaction reinject

All checklist items done: source fallback, steer delivery, kept inject entries, 93 tests, b003-repro gate; full two-compact RPC deferred. Co-authored-by: Cursor <cursoragent@cursor.com>
BACKLOG: close B-003 — Phase 15 mid-turn compaction reinject fix
2026-06-18 23:04:02 +07:00 · 2026-06-18 23:03:09 +07:00 · 2026-06-18 23:02:39 +07:00 · 2026-06-18 23:02:38 +07:00 · 2026-06-18 23:02:17 +07:00 · 2026-06-18 23:01:47 +07:00
42 changed files with 3923 additions and 108 deletions
@@ -2,3 +2,5 @@ node_modules/
 dist/
 *.tsbuildinfo
 .DS_Store
+*.ndjson
+*.jsonl
@@ -10,7 +10,7 @@
 |---|---|
 | Продукт | Extension `skill-reinject` для [Pi Coding Agent](https://github.com/earendil-works/pi) |
 | Цель | Отслеживать вызванные skills и повторно инжектить их после **auto** compaction |
-| Статус | Спецификация готова; **фаза 0** завершена; реализация — фазы 1+ в `TODO.md` |
+| Статус | **Фазы 0–15 завершены** (v1 + B-002/B-003); полный RPC two-compact E2E — см. `docs/e2e-b003-post-fix.md` |
 | Целевой API | Публичный `ExtensionAPI` Pi (`extensions.md`), без приватных internal imports |
 | Совместимость | [@capyup/pi-auto-compact](https://github.com/capyup/pi-auto-compact) — режим `defer` по умолчанию (см. SPEC §16) |

@@ -22,6 +22,7 @@ src/
 ├── state.ts
 ├── detect.ts
 ├── expand.ts
+├── kept.ts
 ├── reinject.ts
 ├── auto-compact.ts
 ├── settings.ts
@@ -41,10 +41,36 @@

 ## Открыто

-_Новые пункты — ниже (следующий id: **B-001**)._
+_Новые пункты — ниже (следующий id: **B-004**)._

 ---

 ## Закрыто

-_Пусто._
+### B-003 · done · e2e · 2026-06-18 (закрыт 2026-06-18)
+
+- **Сценарий:** Длинная сессия `gitlab-mr-review` + pi-auto-compact; auto compaction в ходе Phase 6 review (issue #480334)
+- **Проблема:** Второй подряд auto compaction не re-inject'ит tracked skill; `/skill-reinject` status показывает `last compaction: none`
+- **Место:** `session_before_compact` / `session_compact` / defer + `before_agent_start`; артефакт `lost-reinject.jsonl`
+- **Факт:** Compaction #1: `lastCompactionSource: auto`, inject OK. Compaction #2 mid-turn: `lastCompactionSource: null` (no `session_before_compact`), defer consume only on user prompt → skill lost
+- **Закрытие:** Phase 15 (`a07ddef`…`c12a371`); `ensureCompactionSourceMarked` on `session_compact`, mid-turn `sendMessage`/`steer`, kept-window `skill-reinject:inject`, debug diag; 93 unit tests; `scripts/b003-repro.mjs`; full two-compact RPC deferred (`docs/e2e-b003-post-fix.md`)
+- **Предложение:** (реализовано) source fallback §8, steer delivery §6.5.1, kept custom §6.4
+
+### B-002 · done · e2e · 2026-06-17 (закрыт 2026-06-17)
+
+- **Сценарий:** Manual E2E §12.2 п.2–5, §12.3 п.3–7, §13 п.3/9/10 — auto compaction → re-inject tracked skills; `/skill-reinject now` как контроль
+- **Проблема:** skill из `--skill /path/to/SKILL.md` разворачивается в контекст, но не попадает в `resourceLoader` → `planReinject` / `reinjectNow` отфильтровывают его (`filterSkillsNeedingReinject` требует `registeredNames.has(name)`)
+- **Место:** `src/skills-registry.ts`, `src/kept.ts`, `src/reinject.ts`, `before_agent_start`
+- **Факт:** pre-fix RPC: `registered` мог быть пуст при `loadSkills` fallback; skill вне kept + пустой registry → `planned=[]`. Post-fix: defer plan без registry на compact, consume/build loose fallback по `tracked.filePath`, `requireRegistered` (default false)
+- **Закрытие:** Phase 14 commits (`aca68e7`…`e3873d7`); unit regression 84 tests; `docs/e2e-b002-post-fix.md` — short RPC session держит skill в kept (reinject не нужен); полный compact→reinject RPC требует длинной сессии
+- **Предложение:** (реализовано) `planDeferredReinject`, `filterPendingReinjectForConsume`, loose `buildReinjectBlocks` / `reinjectNow`, README `requireRegistered`
+
+### B-001 · done · e2e · 2026-06-17 (закрыт 2026-06-17)
+
+- **Сценарий:** Manual E2E §12.2 / §12.3 — блокировка из‑за отсутствия LLM
+- **Проблема:** в среде агента не было доступного LLM
+- **Место:** `pi --mode rpc` / compaction
+- **Факт:** изначально нет API key; `pi-llama-cpp` → `192.168.1.159:8080` недоступен. После настройки: `pi-provider-litellm`, `~/.pi/agent/litellm-models.json`, `auth.json`; `pi --list-models` → `Eltex-Coder-Senior`, `Eltex-Kimi`; compaction и agent turn работают
+- **Обход:** LiteLLM proxy (`llm2.eltex.loc:4000`), default model `Eltex-Coder-Senior` в `settings.json`
+- **Закрытие:** LLM доступен; частичный RPC smoke пройден (коммиты phase 13). Оставшиеся E2E-дыры — B-002
+
@@ -2,35 +2,89 @@

 Pi Coding Agent extension: отслеживает вызванные skills и повторно инжектит их после auto compaction.

-**Статус:** спецификация (реализация не начата)
+**Статус:** реализовано (v1)

-## Документация
+## Установка

- [SPEC.md](./SPEC.md) — полное ТЗ с ссылками на документацию Pi
+```bash
+# из клона репозитория
+pi -e ./src/index.ts

-## Совместимость
+# или абсолютный путь
+pi -e ~/Documents/repos/pi-auto-reinjection/src/index.ts
+```

-Рассчитан на совместную работу с [@capyup/pi-auto-compact](https://github.com/capyup/pi-auto-compact) (auto-continue после compaction). Детали — [SPEC.md §16](./SPEC.md#16-совместимость-с-capyuppi-auto-compact).
+Для постоянной установки укажите путь к `src/index.ts` в `~/.pi/agent/settings.json` → `extensions` (нужен весь каталог `src/`, не один файл). См. [Pi extensions](https://github.com/earendil-works/pi/blob/main/packages/coding-agent/docs/extensions.md).

-## Быстрый контекст
-
-Pi хранит в контексте только описания skills; полный `SKILL.md` теряется при compaction. Extension решает это re-inject'ом через тот же механизм, что `/skill:name`.
-
-По умолчанию **выключено**. Включение:
+По умолчанию extension **выключен**. Включение:

 ```text
 /skill-reinject on          # эта сессия
 /skill-reinject global on   # навсегда (~/.pi/agent/settings.json)
 ```

-## Установка (план)
+## Команда `/skill-reinject`

-```bash
-pi -e ./src/index.ts   # после реализации
+```text
+/skill-reinject                          # статус (enabled, delivery, tracked, pending)
+/skill-reinject on | off | reset         # session override
+/skill-reinject global on | off          # глобальный default
+/skill-reinject list | clear             # tracked skills
+/skill-reinject now                      # принудительный re-inject (debug)
+/skill-reinject integration auto|defer|immediate|off
 ```

-## Ссылки
+Алиасы: `/sr`, `/skills-reinject`. Footer status: `on·N` / `off·N`.

+Полный синтаксис и настройки — [SPEC.md §7](./SPEC.md#7-команда-skill-reinject).
+
+## Как это работает
+
+Pi хранит в контексте только описания skills; полный `SKILL.md` теряется при compaction. Extension отслеживает вызванные skills (`/skill:name`, skill-блоки, `read` на `SKILL.md` при `trackReadPaths: true`) и после **auto** compaction повторно инжектит отсутствующие в kept window блоки — тем же форматом, что `/skill:name`.
+
+## Skills via `--skill` and discovery paths
+
+| Источник skill | Трекинг | Re-inject после compact |
+|----------------|---------|-------------------------|
+| Discovery (`~/.pi/agent/skills`, `.pi/skills`) | Да | По имени в resourceLoader |
+| CLI `--skill /path/to/SKILL.md` | Да (`slash` / skill-блок) | Да, если `SKILL.md` ещё на диске по `tracked.filePath` |
+| `--resume` без повторного `--skill` | Восстанавливается из state entry / rescan | Да при `requireRegistered: false` (default) |
+
+По умолчанию `skillReinject.requireRegistered` — **`false`**: tracked skill re-injectится с диска, даже если `resourceLoader` его не знает (типично для `--skill` вне discovery paths). Уведомление: `re-injected "<name>" from disk`.
+
+Строгий режим — только skills из resourceLoader:
+
+```json
+{
+  "skillReinject": {
+    "requireRegistered": true
+  }
+}
+```
+
+Полезно при `--no-skills` или осознанном отключении skill через `pi config`, когда re-inject с диска нежелателен.
+
+## Совместимость с pi-auto-compact
+
+Рассчитан на совместную работу с [@capyup/pi-auto-compact](https://github.com/capyup/pi-auto-compact). При обнаружении команды `auto-compact` re-inject идёт через `defer`:
+
+- **Idle** (turn boundary): очередь на `before_agent_start` — в том же turn, что follow-up pi-auto-compact, без гонки `sendUserMessage`.
+- **Mid-turn** (`!isIdle`, после tool result): немедленная доставка через `sendMessage` с `deliverAs: "steer"` — skill попадает в контекст до следующего LLM-вызова без user prompt.
+
+Если `/skill-reinject` показывает `last compaction: none` после auto compact — включите `"debug": true` в `skillReinject` и смотрите notify `skill-reinject [session_compact]`: поля `compactionSource`, `sourceInferred`, `deliveryBranch`, `isIdle`.
+
+**Coexistence с Pi default auto-compaction:** оба механизма могут сработать в одной сессии. При использовании pi-auto-compact можно отключить встроенный compaction Pi (`"compaction.enabled": false` в settings) или оставить оба — skill-reinject отработает после каждого **auto** compaction. Extension не отключает чужой compaction; при первом обнаружении обоих механизмов показывает одноразовый hint.
+
+## Разработка
+
+```bash
+npm run typecheck   # tsc --noEmit
+npm test            # vitest
+```
+
+## Документация
+
+- [SPEC.md](./SPEC.md) — полное ТЗ
 - [Pi extensions](https://github.com/earendil-works/pi/blob/main/packages/coding-agent/docs/extensions.md)
 - [Pi skills](https://github.com/earendil-works/pi/blob/main/packages/coding-agent/docs/skills.md)
 - [Pi compaction](https://github.com/earendil-works/pi/blob/main/packages/coding-agent/docs/compaction.md)
@@ -118,7 +118,7 @@ References are relative to {baseDir}.

 Для N skills при доставке через `sendUserMessage`: отдельное сообщение на skill, порядок = порядок первого вызова в сессии.

-При доставке через `before_agent_start` (§6.5, режим `defer`, в т.ч. с [pi-auto-compact](https://github.com/capyup/pi-auto-compact)): **одно** injected message со всеми skill-блоками подряд (меньше turn'ов, нет гонки с follow-up).
+При доставке через `before_agent_start` или mid-turn `sendMessage`/`steer` (§6.5, режим `defer`, в т.ч. с [pi-auto-compact](https://github.com/capyup/pi-auto-compact)): **одно** injected message с `customType: "skill-reinject:inject"` и всеми skill-блоками подряд (меньше turn'ов, нет гонки с follow-up).

 ---

@@ -141,7 +141,7 @@ interface ExtensionState {
  sessionOverride: boolean | null;
  skills: TrackedSkill[];  // dedupe by name, preserve insertion order
  lastCompactionSource: "auto" | "manual" | null;
-  /** Skills, ожидающие re-inject на следующем before_agent_start (§6.5) */
+  /** Skills, ожидающие re-inject (§6.5): idle → before_agent_start; mid-turn → steer на session_compact */
  pendingReinject: string[];  // skill names
 }

@@ -182,7 +182,12 @@ In-memory кэш + персистенция через `pi.appendEntry` при
 Перед re-inject:

 1. Взять entries от `compactionEntry.firstKeptEntryId` до хвоста ветки.
-2. Для каждого tracked skill: если в kept user messages есть `<skill name="{name}"` → **пропустить** re-inject для этого skill.
+2. Для каждого tracked skill: если в kept window есть `<skill name="{name}"` → **пропустить** re-inject для этого skill.
+3. Источники текста в kept slice:
+   - user messages (`type === "message"`, `role === "user"`);
+   - наши reinject-сообщения: `type === "custom_message"` с `customType === "skill-reinject:inject"` (§6.5.1) — skill-блоки в `content`, не в user role.
+
+Пункт 3 закрывает ложное «skill вне kept» после успешного defer-reinject: `custom_message` не user message, но skill уже в контексте turn'а. Без этого второй compaction подряд снова планирует reinject (лишний inject; см. §16.6).

 ### 6.5. Доставка после compaction

@@ -191,9 +196,20 @@ In-memory кэш + персистенция через `pi.appendEntry` при
 #### 6.5.1. Режим `defer` (рекомендуемый по умолчанию при наличии pi-auto-compact)

 1. На `session_compact`: записать имена skills в `state.pendingReinject` (не вызывать `sendUserMessage`).
-2. На следующем `before_agent_start`: если `pendingReinject` не пуст — вернуть injected `message` с объединёнными skill-блоками, очистить очередь.
+2. Доставка — **одна точка решения** на `session_compact` по `ctx.isIdle()`:

-Skills попадают в контекст **в том же turn**, что и kickoff-сообщение (в т.ч. auto-continue от pi-auto-compact), **без гонки** `sendUserMessage`.
+| Условие на `session_compact` | Доставка |
+|------------------------------|----------|
+| `ctx.isIdle()` | Оставить `pendingReinject`; consume на следующем `before_agent_start` (kickoff pi-auto-compact follow-up / user prompt) |
+| `!ctx.isIdle()` (mid-turn compaction) | Немедленно: `pi.sendMessage({ customType: "skill-reinject:inject", content, display: true }, { deliverAs: "steer" })`; очистить `pendingReinject`; записать `compactionEntry.id` в runtime, чтобы `before_agent_start` **не** дублировал inject для этого compaction |
+
+3. На `before_agent_start` (idle-path): если `pendingReinject` не пуст и steer для этого compaction ещё не доставлялся — вернуть injected `message` с `customType: "skill-reinject:inject"` и объединёнными skill-блоками, очистить очередь.
+
+**Mid-turn steer:** `deliverAs: "steer"` ставит skill-блоки в очередь до следующего LLM-вызова **в том же turn** (после tool result, без user prompt). Это закрывает сценарий, когда pi-auto-compact компактирует mid-turn и **не** шлёт follow-up (агент не idle) — consume только на `before_agent_start` теряет skill до следующего сообщения пользователя (B-003).
+
+**Не** вызывать `sendUserMessage` в `session_compact` (§16.2). Steer — не user message и не конкурирует с pi-auto-compact follow-up на turn boundary.
+
+На turn-boundary path skills попадают в контекст **в том же turn**, что и kickoff-сообщение (в т.ч. auto-continue от pi-auto-compact), **без гонки** `sendUserMessage`.

 #### 6.5.2. Режим `immediate` (`sendUserMessage`)

@@ -287,19 +303,30 @@ Extension event `session_compact` **не** передаёт `reason` ([SessionCo
 **Стратегия v1:**

 ```typescript
-// input handler (до expansion)
+// input handler (до expansion) — единственный путь manual
 if (text.startsWith("/compact")) pendingCompactionSource = "manual";

-// session_before_compact
-if (pendingCompactionSource !== "manual") pendingCompactionSource = "auto";
+function ensureCompactionSourceMarked(runtime) {
+  if (runtime.pendingCompactionSource !== "manual") {
+    runtime.pendingCompactionSource = "auto";
+  }
+}
+
+// session_before_compact
+ensureCompactionSourceMarked(runtime);
+
+// session_compact — safety net, если before_compact не пришёл (mid-turn, гонка хуков)
+ensureCompactionSourceMarked(runtime);

-// session_compact
 const shouldReinject =
  effectiveEnabled &&
  (pendingCompactionSource === "auto" || settings.reinjectOnManualCompaction);
+state.lastCompactionSource = pendingCompactionSource;
 pendingCompactionSource = null;
 ```

+**Fallback на `session_compact`:** если `session_before_compact` не отработал, `pendingCompactionSource` остаётся `null` → без fallback `lastCompactionSource: null`, `shouldReinject === false`, status `last compaction: none` при реальном auto compact (B-003). Всё, что не помечено явным `/compact` в `input`, на `session_compact` считается **auto**.
+
 Ручной RPC compact (`{type: "compact"}`) тоже помечать как `manual` если extension получает соответствующий сигнал (v2).

 ---
@@ -420,9 +447,10 @@ cp -r src/index.ts ~/.pi/agent/extensions/skill-reinject.ts
 - [ ] Tracked skills: `/skill:name`, skill-block в user msg, `read` на `SKILL.md`
 - [ ] State переживает `/resume` той же сессии
 - [ ] Footer status показывает on/off и count
- [ ] Нет duplicate skill blocks для skills уже в kept window
+- [ ] Нет duplicate skill blocks для skills уже в kept window (включая `skill-reinject:inject` в kept slice, §6.4)
 - [ ] С [pi-auto-compact](https://github.com/capyup/pi-auto-compact): auto-detect, режим `defer`, нет гонки `sendUserMessage`, continue после compaction работает
 - [ ] С pi-auto-compact: ручной `/compact` не ломает ни один extension
+- [ ] **Два auto compaction подряд** (в т.ч. второй mid-turn без user prompt): после каждого — tracked skills в контексте или явный skip (`skipped-kept` в `debug`); `/skill-reinject` → `last compaction: auto`, не `none` (§8 fallback, §6.5.1 steer)

 ---

@@ -442,7 +470,7 @@ cp -r src/index.ts ~/.pi/agent/extensions/skill-reinject.ts
 |------|-----------|
 | Re-inject раздувает контекст (N больших skills) | `skillReinject.maxSkills` (default unlimited; soft warn > 3) |
 | `sendUserMessage` запускает нежеланный turn | `defer` по умолчанию при pi-auto-compact; иначе `triggerTurn: false` |
-| Гонка `sendUserMessage` с pi-auto-compact follow-up | §16: не слать в `session_compact`; `before_agent_start` |
+| Гонка `sendUserMessage` с pi-auto-compact follow-up | §16: не слать `sendUserMessage` в `session_compact`; idle → `before_agent_start`; mid-turn → `sendMessage`/`steer` (§6.5.1) |
 | Нельзя отличить auto/manual без эвристики | input hook на `/compact`; pi-auto-compact manual `/compact` не в его `onComplete` |
 | Двойной compaction (Pi default + pi-auto-compact) | документировать; опционально warn в status |
 | Pi изменит формат skill block | version в state; тест на `parseSkillBlock` regex |
@@ -473,7 +501,7 @@ cp -r src/index.ts ~/.pi/agent/extensions/skill-reinject.ts
 1. Агент перестаёт быть idle → pi-auto-compact **не** шлёт follow-up → **сессия замирает** после compaction.
 2. Или оба шлют сообщения в одном tick → `"Agent is already processing"` ([комментарий в auto-compact.ts](https://github.com/capyup/pi-auto-compact/blob/main/extensions/auto-compact.ts)).

-**Вывод:** при обнаружении pi-auto-compact re-inject **обязан** идти через `defer` + `before_agent_start`, не через конкурирующий `sendUserMessage`.
+**Вывод:** при обнаружении pi-auto-compact re-inject **обязан** идти через режим `defer`, не через конкурирующий `sendUserMessage` в `session_compact`. Idle: `before_agent_start`; mid-turn (`!isIdle`): `sendMessage` с `deliverAs: "steer"` (§6.5.1) — тот же инвариант §16.5, без user message.

 ### 16.3. Целевой совместный flow

@@ -483,15 +511,18 @@ turn_start / turn_end / emergency
        ▼
 pi-auto-compact: ctx.compact()
        │
-        ├── session_before_compact (наш hook: только mark source=auto)
+        ├── session_before_compact (наш hook: mark source=auto)
        ├── … Pi summarization …
        ├── session_compact (наш hook: pendingReinject := skills ∖ kept)
-        └── onComplete → setImmediate → sendUserMessage("Auto-compact ran…")
+        │       │
+        │       ├── isIdle → pending для before_agent_start
+        │       └── !isIdle → sendMessage steer (§6.5.1), без follow-up
+        └── onComplete → setImmediate → if isIdle: sendUserMessage("Auto-compact ran…")
                    │
                    ▼
-            prompt() → before_agent_start (наш hook)
+            prompt() → before_agent_start (наш hook, idle-path)
                    │
-                    ├── inject: <skill>…</skill> × N   ← re-inject
+                    ├── inject: <skill>…</skill> × N   ← re-inject (если не steer'нули)
                    └── user prompt: "Auto-compact ran…"  ← kickoff pi-auto-compact
                    │
                    ▼
@@ -519,7 +550,7 @@ function detectPiAutoCompact(pi: ExtensionAPI): boolean {
 | Значение | Поведение |
 |----------|-----------|
 | `"auto"` (default) | `defer` если `detectPiAutoCompact()`, иначе по `triggerTurn` |
-| `"defer"` | всегда `before_agent_start`, даже без pi-auto-compact |
+| `"defer"` | idle: `before_agent_start`; mid-turn (`!isIdle`): steer на `session_compact` (§6.5.1); никогда `sendUserMessage` в `session_compact` |
 | `"immediate"` | всегда `sendUserMessage` (для отладки; с pi-auto-compact — риск §16.2) |
 | `"off"` | игнорировать detect; только `triggerTurn` |

@@ -538,10 +569,12 @@ function detectPiAutoCompact(pi: ExtensionAPI): boolean {

 | Сценарий | Результат |
 |----------|-----------|
-| Auto-compact + follow-up | Следующий `before_agent_start` — наш inject; skills в контексте |
-| User печатает во время compaction | pi-auto-compact молчит; user prompt → наш inject на его turn |
+| Auto-compact + follow-up (idle) | Следующий `before_agent_start` — наш inject; skills в контексте |
+| Auto-compact **mid-turn** (`!isIdle`, нет follow-up) | Steer на `session_compact` (§6.5.1); skills до следующего LLM-вызова в том же turn |
+| User печатает во время compaction | pi-auto-compact молчит; user prompt → наш inject на его turn (`before_agent_start`) |
 | pi-auto-compact `keep-bookends` / `summarize-all` | Kept window определяем по `compactionEntry.firstKeptEntryId` в session branch (§6.4), не по их процентам |
-| Два compaction подряд | Каждый `session_compact` пересчитывает `pendingReinject`; дедуп по kept window |
+| Два compaction подряд | Каждый `session_compact` пересчитывает `pendingReinject`; source fallback §8; дедуп по kept window включая `skill-reinject:inject` (§6.4) |
+| Turn-boundary compact после steer | `before_agent_start` не дублирует inject, если steer уже доставил для `compactionEntry.id` этого compaction |

 ### 16.7. Coexistence с Pi default auto-compaction

@@ -68,9 +68,9 @@

 | Сейчас | Цель |
 |--------|------|
-| Только `SPEC.md` + `README.md` | Рабочий extension `src/index.ts` + тесты |
+| Extension v1 реализован (`src/` + 62 теста) | Рабочий extension `src/index.ts` + тесты |
 | Default off | `/skill-reinject on` / `global on` |
-| Нет re-inject после compaction | Auto compaction → re-inject tracked skills (SPEC §5–6) |
+| Re-inject после auto compaction | Auto compaction → re-inject tracked skills (SPEC §5–6) |

 ---

@@ -105,8 +105,10 @@
 | 11 | Команды и UI | 1, 2, 6, 7 | §7 |
 | 12 | Edge cases и полировка | 7–11 | §11 |
 | 13 | Приёмка и документация | 0–12 | §12–13 |
+| 14 | Re-inject для `--skill` / не-discovery skills (B-002) | 7, 9, 10, 13 | §5.2, §6.2, §11; BACKLOG B-002 |
+| 15 | Mid-turn / пропущенный compaction (B-003) | 7, 8, 12, 14 | §5.2, §6.4–6.5, §8, §13, §16; BACKLOG B-003 |

-**Порядок:** фазы 0→13; внутри фазы — сверху вниз. Параллельно после фазы 0 можно вести 1 и 2; фазы 3 и 4 — независимы друг от друга.
+**Порядок:** фазы 0→13; внутри фазы — сверху вниз. Параллельно после фазы 0 можно вести 1 и 2; фазы 3 и 4 — независимы друг от друга. Фаза 15 — после 14.

 ---

@@ -141,112 +143,173 @@

 ### Фаза 3 — Детекция skills

- [ ] **detect.ts slash** — `detectSlashSkill(text)` → `/^\/skill:([a-z0-9-]+)/`; зачем: источник `slash` §6.2
- [ ] **detect.ts skill-block** — `parseSkillBlocksFromText(text)` (regex как `parseSkillBlock`); зачем: источник `skill-block` §6.2
- [ ] **detect.ts read-path** — `matchReadPathToSkill(path, skills)` по `filePath` из resourceLoader; зачем: источник `read` §6.2
- [ ] **detect.ts trackReadPaths gate** — пропуск read-детекции при `trackReadPaths: false`; зачем: §6.2, §3
- [ ] **test/detect.test.ts** — slash, blocks, read match, trackReadPaths off; зачем: §12.1
+- [x] **detect.ts slash** — `detectSlashSkill(text)` → `/^\/skill:([a-z0-9-]+)/`; зачем: источник `slash` §6.2
+- [x] **detect.ts skill-block** — `parseSkillBlocksFromText(text)` (regex как `parseSkillBlock`); зачем: источник `skill-block` §6.2
+- [x] **detect.ts read-path** — `matchReadPathToSkill(path, skills)` по `filePath` из resourceLoader; зачем: источник `read` §6.2
+- [x] **detect.ts trackReadPaths gate** — пропуск read-детекции при `trackReadPaths: false`; зачем: §6.2, §3
+- [x] **test/detect.test.ts** — slash, blocks, read match, trackReadPaths off; зачем: §12.1

 ---

 ### Фаза 4 — Expand skill-блоков

- [ ] **expand.ts readBody** — `readSkillBody(filePath)` + strip YAML frontmatter; комментарий «mirror agent-session»; зачем: §5.3, §10
- [ ] **expand.ts formatBlock** — XML `<skill name location>…</skill>` с `baseDir`; зачем: повтор `_expandSkillCommand` §5.3
- [ ] **expand.ts suffix** — опциональный суффикс из `settings.suffix`; зачем: §5.3
- [ ] **expand.ts expandSkill** — публичная функция: skill meta → готовый user text; зачем: reinject + `/skill-reinject now`
- [ ] **test/expand.test.ts** — frontmatter strip, paths, suffix; зачем: §12.1
+- [x] **expand.ts readBody** — `readSkillBody(filePath)` + strip YAML frontmatter; комментарий «mirror agent-session»; зачем: §5.3, §10
+- [x] **expand.ts formatBlock** — XML `<skill name location>…</skill>` с `baseDir`; зачем: повтор `_expandSkillCommand` §5.3
+- [x] **expand.ts suffix** — опциональный суффикс из `settings.suffix`; зачем: §5.3
+- [x] **expand.ts expandSkill** — публичная функция: skill meta → готовый user text; зачем: reinject + `/skill-reinject now`
+- [x] **test/expand.test.ts** — frontmatter strip, paths, suffix; зачем: §12.1

 ---

 ### Фаза 5 — Kept window

- [ ] **kept.ts slice** — `getKeptEntries(branch, firstKeptEntryId)` от compaction entry до хвоста; зачем: §6.4
- [ ] **kept.ts present** — `skillsPresentInKeptWindow(keptEntries, skillNames)` по `<skill name="…"`; зачем: не дублировать блоки §6.4, критерий §13
- [ ] **kept.ts filter** — `filterSkillsNeedingReinject(tracked, kept, registeredNames)`; зачем: вход для `pendingReinject` §5.2
- [ ] **test/kept-window.test.ts** — in / not in kept, пустой kept; зачем: §12.1
+- [x] **kept.ts slice** — `getKeptEntries(branch, firstKeptEntryId)` от `firstKeptEntryId` до хвоста; зачем: §6.4
+- [x] **kept.ts present** — `skillsPresentInKeptWindow(keptEntries, skillNames)` по `<skill name="…"`; зачем: не дублировать блоки §6.4, критерий §13
+- [x] **kept.ts filter** — `filterSkillsNeedingReinject(tracked, kept, registeredNames)`; зачем: вход для `pendingReinject` §5.2
+- [x] **test/kept-window.test.ts** — in / not in kept, пустой kept; зачем: §12.1

 ---

 ### Фаза 6 — pi-auto-compact

- [ ] **auto-compact.ts detect** — `detectPiAutoCompact(pi)` через `getCommands()` → `auto-compact`; кэш в `RuntimeFlags`; зачем: §16.4
- [ ] **auto-compact.ts deliveryMode** — `resolveDeliveryMode(settings, runtime, sessionIntegrationOverride)` по таблице §6.5.3; зачем: defer vs immediate
- [ ] **auto-compact.ts constants** — `PI_AUTO_COMPACT_FOLLOW_UP_PREFIXES` (документация/тесты, не runtime match); зачем: §16.9
- [ ] **auto-compact.ts hint** — одноразовый `ui.notify` при detect Pi default compaction + pi-auto-compact; зачем: §16.7
+- [x] **auto-compact.ts detect** — `detectPiAutoCompact(pi)` через `getCommands()` → `auto-compact`; кэш в `RuntimeFlags`; зачем: §16.4
+- [x] **auto-compact.ts deliveryMode** — `resolveDeliveryMode(settings, runtime, sessionIntegrationOverride)` по таблице §6.5.3; зачем: defer vs immediate
+- [x] **auto-compact.ts constants** — `PI_AUTO_COMPACT_FOLLOW_UP_PREFIXES` (документация/тесты, не runtime match); зачем: §16.9
+- [x] **auto-compact.ts hint** — одноразовый `ui.notify` при detect Pi default compaction + pi-auto-compact; зачем: §16.7

 ---

 ### Фаза 7 — Re-inject оркестрация

- [ ] **reinject.ts plan** — `planReinject(state, settings, ctx, compactionEvent)` → имена skills с учётом kept + registration; зачем: §5.2 п.4–5
- [ ] **reinject.ts defer enqueue** — на `session_compact`: `pendingReinject := plan`, без `sendUserMessage`; зачем: §6.5.1, §16.2
- [ ] **reinject.ts defer inject** — на `before_agent_start`: объединённое message со всеми блоками, clear queue; зачем: §5.3, §6.5.1
- [ ] **reinject.ts immediate idle** — первый skill обычный, остальные `followUp`; зачем: §6.5.2
- [ ] **reinject.ts immediate streaming** — `willRetry` / streaming → все `deliverAs: "followUp"`; зачем: §5.2, §6.5.2
- [ ] **reinject.ts skip missing** — skill удалён с диска → skip + `ui.notify` warning; зачем: §11
- [ ] **reinject.ts force now** — `reinjectNow(pi, state, settings)` для `/skill-reinject now`; зачем: §7.1 debug
+- [x] **reinject.ts plan** — `planReinject(state, settings, ctx, compactionEvent)` → имена skills с учётом kept + registration; зачем: §5.2 п.4–5
+- [x] **reinject.ts defer enqueue** — на `session_compact`: `pendingReinject := plan`, без `sendUserMessage`; зачем: §6.5.1, §16.2
+- [x] **reinject.ts defer inject** — на `before_agent_start`: объединённое message со всеми блоками, clear queue; зачем: §5.3, §6.5.1
+- [x] **reinject.ts immediate idle** — первый skill обычный, остальные `followUp`; зачем: §6.5.2
+- [x] **reinject.ts immediate streaming** — `willRetry` / streaming → все `deliverAs: "followUp"`; зачем: §5.2, §6.5.2
+- [x] **reinject.ts skip missing** — skill удалён с диска → skip + `ui.notify` warning; зачем: §11
+- [x] **reinject.ts force now** — `reinjectNow(pi, state, settings)` для `/skill-reinject now`; зачем: §7.1 debug

 ---

 ### Фаза 8 — Источник compaction

- [ ] **compaction.ts state machine** — `pendingCompactionSource: "auto" \| "manual" \| null`; зачем: §8
- [ ] **compaction.ts input hook** — `text.startsWith("/compact")` → manual; зачем: §8
- [ ] **compaction.ts before_compact** — если не manual → auto; зачем: §8
- [ ] **compaction.ts shouldReinject** — gate: enabled + source + `reinjectOnManualCompaction`; reset после `session_compact`; зачем: §5.2, §8, критерий §13
+- [x] **compaction.ts state machine** — `pendingCompactionSource: "auto" \| "manual" \| null`; зачем: §8
+- [x] **compaction.ts input hook** — `text.startsWith("/compact")` → manual; зачем: §8
+- [x] **compaction.ts before_compact** — если не manual → auto; зачем: §8
+- [x] **compaction.ts shouldReinject** — gate: enabled + source + `reinjectOnManualCompaction`; reset после `session_compact`; зачем: §5.2, §8, критерий §13

 ---

 ### Фаза 9 — Хуки отслеживания

- [ ] **index.ts input track** — на `input`: slash `/skill:name` → `trackSkill`; зачем: §6.2 #1
- [ ] **index.ts message_end** — user messages → skill-block scan; зачем: §6.2 #2
- [ ] **index.ts tool read** — `tool_call`/`tool_result` с `read` на `SKILL.md`; зачем: §6.2 #3
- [ ] **index.ts persist on track** — `saveState` после изменения skills / session override; зачем: §6.1
- [ ] **index.ts session_compact wire** — связать §7–8: plan → defer/immediate; зачем: end-to-end trigger
+- [x] **index.ts input track** — на `input`: slash `/skill:name` → `trackSkill`; зачем: §6.2 #1
+- [x] **index.ts message_end** — user messages → skill-block scan; зачем: §6.2 #2
+- [x] **index.ts tool read** — `tool_call`/`tool_result` с `read` на `SKILL.md`; зачем: §6.2 #3
+- [x] **index.ts persist on track** — `saveState` после изменения skills / session override; зачем: §6.1
+- [x] **index.ts session_compact wire** — связать §7–8: plan → defer/immediate; зачем: end-to-end trigger

 ---

 ### Фаза 10 — Восстановление сессии

- [ ] **index.ts session_start load** — load state entry + read global settings + `detectPiAutoCompact`; зачем: §5.1, §16.4
- [ ] **index.ts branch rescan** — если нет state entry: full rescan user messages в `getBranch()`; зачем: §6.3
- [ ] **index.ts resume reload** — `reason: "reload" \| "resume" \| "switch"` — тот же путь; зачем: §6.3, `/tree` §11
- [ ] **index.ts session_shutdown** — flush pending `saveState`; зачем: §11
+- [x] **index.ts session_start load** — load state entry + read global settings + `detectPiAutoCompact`; зачем: §5.1, §16.4
+- [x] **index.ts branch rescan** — если нет state entry: full rescan user messages в `getBranch()`; зачем: §6.3
+- [x] **index.ts resume reload** — `reason: "reload" \| "resume" \| "switch"` — тот же путь; зачем: §6.3, `/tree` §11
+- [x] **index.ts session_shutdown** — flush pending `saveState`; зачем: §11

 ---

 ### Фаза 11 — Команды и UI

- [ ] **commands.ts register** — `pi.registerCommand("skill-reinject", handler)`; зачем: §7
- [ ] **commands.ts status** — вывод без аргументов по формату §7.2 (enabled layer, delivery, tracked, pending, last compaction)
- [ ] **commands.ts session toggle** — `on` / `off` / `reset` → session override + persist; зачем: §5.1, §7.1
- [ ] **commands.ts global toggle** — `global on` / `global off` → settings.json; зачем: §7.1, критерий §13
- [ ] **commands.ts list clear** — `list` tracked skills; `clear` без сброса toggle; зачем: §7.1
- [ ] **commands.ts integration** — `integration auto|defer|immediate|off` session override в config entry; зачем: §7.1, §16.4
- [ ] **commands.ts now** — делегат в `reinjectNow`; зачем: §7.1
- [ ] **commands.ts aliases** — опционально `/sr`, `/skills-reinject`; зачем: §7.1
- [ ] **commands.ts status line** — `ctx.ui.setStatus("skill-reinject", "on·N")` на изменениях; зачем: §7.2, критерий §13
+- [x] **commands.ts register** — `pi.registerCommand("skill-reinject", handler)`; зачем: §7
+- [x] **commands.ts status** — вывод без аргументов по формату §7.2 (enabled layer, delivery, tracked, pending, last compaction)
+- [x] **commands.ts session toggle** — `on` / `off` / `reset` → session override + persist; зачем: §5.1, §7.1
+- [x] **commands.ts global toggle** — `global on` / `global off` → settings.json; зачем: §7.1, критерий §13
+- [x] **commands.ts list clear** — `list` tracked skills; `clear` без сброса toggle; зачем: §7.1
+- [x] **commands.ts integration** — `integration auto|defer|immediate|off` session override в config entry; зачем: §7.1, §16.4
+- [x] **commands.ts now** — делегат в `reinjectNow`; зачем: §7.1
+- [x] **commands.ts aliases** — опционально `/sr`, `/skills-reinject`; зачем: §7.1
+- [x] **commands.ts status line** — `ctx.ui.setStatus("skill-reinject", "on·N")` на изменениях; зачем: §7.2, критерий §13

 ---

 ### Фаза 12 — Edge cases и полировка

- [ ] **reinject.ts manual defer clear** — на manual compaction: не enqueue (или clear `pendingReinject` на следующем user prompt при default); зачем: §16.5, §12.3 п.6
- [ ] **reinject.ts name collision** — два skill с одним name → первый из resourceLoader + warn; зачем: §11
- [ ] **reinject.ts maxSkills warn** — soft warn при >3 (если `maxSkills` не задан — unlimited); зачем: §15
- [ ] **commands.ts no-ui** — RPC / `hasUI === false`: команды без падения, notify no-op; зачем: §11
- [ ] **index.ts double compact** — каждый `session_compact` пересчитывает `pendingReinject`; зачем: §16.6
+- [x] **reinject.ts manual defer clear** — на manual compaction: не enqueue (или clear `pendingReinject` на следующем user prompt при default); зачем: §16.5, §12.3 п.6
+- [x] **reinject.ts name collision** — два skill с одним name → первый из resourceLoader + warn; зачем: §11
+- [x] **reinject.ts maxSkills warn** — soft warn при >3 (если `maxSkills` не задан — unlimited); зачем: §15
+- [x] **commands.ts no-ui** — RPC / `hasUI === false`: команды без падения, notify no-op; зачем: §11
+- [x] **index.ts double compact** — каждый `session_compact` пересчитывает `pendingReinject`; зачем: §16.6

 ---

 ### Фаза 13 — Приёмка и документация

- [ ] **README.md** — статус «реализовано», установка `pi -e`, ссылка на `/skill-reinject`, coexistence с pi-auto-compact; зачем: §9.1, §16.7
- [ ] **Manual E2E standalone** — прогон чеклиста §12.2 (записать результат в коммит / BACKLOG при сбоях); зачем: §12.2
- [ ] **Manual E2E pi-auto-compact** — прогон §12.3 (defer, нет гонки, manual `/compact`); зачем: критерии §13
- [ ] **Критерии §13** — сверка всех 10 пунктов; расхождения → BACKLOG или правка SPEC
+- [x] **README.md** — статус «реализовано», установка `pi -e`, ссылка на `/skill-reinject`, coexistence с pi-auto-compact; зачем: §9.1, §16.7
+- [x] **Manual E2E standalone** — прогон чеклиста §12.2 (записать результат в коммит / BACKLOG при сбоях); зачем: §12.2
+- [x] **Manual E2E pi-auto-compact** — прогон §12.3 (defer, нет гонки, manual `/compact`); зачем: критерии §13
+- [x] **Критерии §13** — сверка всех 10 пунктов; расхождения → BACKLOG или правка SPEC
+
+---
+
+### Фаза 14 — Re-inject для `--skill` / не-discovery skills (B-002)
+
+Закрывает [BACKLOG B-002](./BACKLOG.md#b-002--open--e2e--2026-06-17): tracked skill, поданный через CLI `--skill` (или вне `~/.pi/agent/skills` / `.pi/skills`), не переживает auto compaction. Корень: `planReinject` / `reinjectNow` режут skill по `registeredNames.has(name)`, но fallback `loadSkills` без `skillPaths` не видит CLI `--skill` пути.
+
+Решение (см. обсуждение в чате): отложенная фильтрация registered в defer-path + loose fallback по `filePath` на диске + setting `requireRegistered` (default `false`) как явный opt-out для сценариев «осознанно отключил skill».
+
+- [x] **diag logging** — `src/diag.ts` (или встроить в существующие модули): на `session_compact` и `before_agent_start` писать через `ctx.ui.notify` под флагом `settings.debug` (новое поле, default `false`) набор `{tracked, kept, registered, planned, pending}`; зачем: без этого фаза 14 — гадание, нужен факт «какой фильтр режет» для каждого сценария
+- [x] **manual repro pre-fix** — RPC E2E из B-002 с `debug: true`; зафиксировать в коммите `Phase 14: …` фактическое значение фильтров (auto vs manual source, размер registered, состав planned); зачем: подтвердить гипотезу «registered пуст в момент session_compact» либо найти другую причину
+- [x] **settings.requireRegistered** — добавить в `SkillReinjectSettings` поле `requireRegistered: boolean` (default `false`); update defaults + test/settings.test.ts; зачем: явный opt-out для сценариев «отключил через `pi config`» / `--no-skills`
+- [x] **kept.ts deferred filter** — выделить `filterSkillsNeedingReinjectByKept(tracked, kept)` без registered-фильтра; оставить старую `filterSkillsNeedingReinject` для immediate path; зачем: разделить две стадии фильтрации
+- [x] **reinject.ts plan defer** — `planDeferredReinject` возвращает `tracked − keptPresent` без registered; `enqueueDeferredReinjectFromCompact` использует его; зачем: §6.5.1 — план фиксируется по kept-window (locked at compaction), registered считается позже
+- [x] **reinject.ts consume defer** — `tryConsumeDeferredReinject` фильтрует `pendingReinject` по свежему `registeredSkills` из `before_agent_start`; если `requireRegistered: false` и skill отсутствует в registered, но `existsSync(tracked.filePath)` → включить + `ui.notify` info (`re-injected from disk`); зачем: главный фикс B-002 для defer-path
+- [x] **reinject.ts reinjectNow loose** — те же правила loose fallback в `reinjectNow`: если `registered.has(name)` false, но filePath на диске и `!requireRegistered` → re-inject; warn в notify; зачем: `/skill-reinject now` работает после `--skill` без перезапуска
+- [x] **reinject.ts buildBlocks loose source** — `buildReinjectBlocks` для loose-кейса использует `tracked.filePath` / `tracked.baseDir` напрямую (без registered lookup); зачем: skill реально читается с диска, даже если resourceLoader его не знает
+- [x] **test/reinject.test.ts deferred** — кейсы: (a) tracked отсутствует в registered, filePath на диске, requireRegistered=false → блок есть + notify info; (b) то же, requireRegistered=true → skip + notify warn; (c) filePath не на диске → skip + warn; зачем: §12.1, регрессионный gate
+- [x] **manual E2E post-fix** — повторить B-002 чеклист (RPC: `--skill ~/.cursor/skills/fup-blame-commits` → `/skill:fup-blame-commits` → auto compact → next turn содержит skill-блок с суффиксом; `/skill-reinject now` после `--skill` тоже работает); зачем: критерий закрытия B-002
+- [x] **README requireRegistered** — раздел «Skills via `--skill` and discovery paths»: как трекаются, что reinject работает для skill ещё на диске даже без повторного `--skill` при `--resume`, как включить strict через `requireRegistered: true`; зачем: §9.1, явная документация развилки
+- [x] **BACKLOG close B-002** — `open` → `done` с датой и ссылкой на коммиты фазы 14; перенести в «Закрыто»; в отдельном коммите `BACKLOG: …`; зачем: правило `dev-backlog.mdc`
+
+---
+
+### Фаза 15 — Mid-turn compaction и пропуск reinject (B-003)
+
+Закрывает [BACKLOG B-003](./BACKLOG.md#b-003--open--e2e--2026-06-18): второй auto compaction подряд не re-inject'ит skill; status `last compaction: none`. Артефакт: `lost-reinject.jsonl` (два compaction за ~11s; первый OK, второй — нет).
+
+**Корень (два связанных сбоя):**
+
+1. **Gate источника compaction** — `lastCompactionSource` выставляется из `pendingCompactionSource` только если до `session_compact` успел отработать `session_before_compact`. На втором compaction в логе `lastCompactionSource: null` → `shouldReinject = false` → очередь сброшена, reinject не планировался.
+2. **Дыра defer-доставки** — consume только на `before_agent_start` (новый user prompt). Mid-turn compaction внутри активного agent loop (после toolResult, без «Auto-compact ran…») не даёт `before_agent_start` до следующего сообщения пользователя → skill теряется до ручного `/skill-reinject now`.
+
+**Дополнительно (двойной compact):** `skillsPresentInKeptWindow` не видит `custom_message` `skill-reinject:inject` → после успешного reinject skill формально «вне kept», и при корректном gate второй compact снова планирует reinject (лишний inject, не причина пропуска в B-003, но усиливает хрупкость).
+
+**Целевое поведение:** каждый auto `session_compact` либо re-inject'ит отсутствующие в kept skills, либо явно skip с причиной в debug; status не показывает ложное `none` после auto compact; нет гонки с pi-auto-compact на turn-boundary path.
+
+**Стратегия доставки (две ветки, одна точка решения на `session_compact`):**
+
+| Условие на `session_compact` | Доставка defer |
+|------------------------------|----------------|
+| `ctx.isIdle()` | Как сейчас: `pendingReinject` → consume на следующем `before_agent_start` (pi-auto-compact follow-up / user prompt) |
+| `!ctx.isIdle()` (mid-turn) | Немедленно: `pi.sendMessage({ customType: "skill-reinject:inject", … }, { deliverAs: "steer" })` — в очередь до следующего LLM-вызова в том же turn; **не** `sendUserMessage` в `session_compact` (§16.2) |
+
+**Стратегия source (fallback §8):** manual — только явный `/compact` в `input`; всё остальное на `session_compact` с `pendingCompactionSource === null` → считать `auto` (вызов `ensureCompactionSourceMarked` и в `session_before_compact`, и в `session_compact` как safety net).
+
+- [x] **SPEC phase 15** — §8: fallback infer `auto` на `session_compact`; §6.5.1: mid-turn defer через `sendMessage`/`steer`; §6.4: kept учитывает `skill-reinject:inject`; §16.6: double compact + mid-turn; §13: критерий «второй compact подряд»; зачем: контракт до кода
+- [x] **compaction.ts ensureSource** — `ensureCompactionSourceMarked(runtime)`: если не `manual` → `auto`; вызывать из `markAutoCompactionBeforeCompact` и экспортировать для `session_compact`; зачем: закрыть `lastCompactionSource: null` (B-003 факт #1)
+- [x] **index.ts compact source fallback** — в `handleSessionCompact` до `consumeCompactionOnSessionCompact`: `ensureCompactionSourceMarked(compactionRuntime)`; зачем: safety net когда `session_before_compact` не пришёл
+- [x] **test/compaction-source-fallback.test.ts** — (a) `session_compact` без prior `before_compact`: source `auto`, `shouldReinject` true; (b) prior `manual` из input: остаётся manual, reinject off по default; зачем: регрессия gate
+- [x] **kept.ts reinject custom** — `skillsPresentInKeptWindow` (или сосед) учитывает entries `type: custom_message`, `customType: skill-reinject:inject` с `<skill name="…"` в `content`; зачем: §6.4, не планировать лишний reinject после успешного inject
+- [x] **test/kept-window.test.ts reinject-custom** — inject custom в kept slice → skill считается present; вне slice → absent; зачем: double-compact dedup
+- [x] **reinject.ts mid-turn steer** — `deliverDeferredReinjectSteer(pi, planned, …)` через `pi.sendMessage` + `DEFERRED_REINJECT_CUSTOM_TYPE`, `deliverAs: "steer"`; clear `pendingReinject`; флаг `compactionRuntime.deferredDeliveredForCompactionId` (или аналог) чтобы `before_agent_start` не дублировал; зачем: B-003 факт #2, §16.2-safe
+- [x] **index.ts mid-turn wire** — в defer-ветке `handleSessionCompact`: после enqueue, если `shouldReinject && planned.length > 0 && !ctx.isIdle()` → steer deliver; иначе оставить pending для `before_agent_start`; persist; зачем: единая развилка idle / mid-turn
+- [x] **index.ts before_agent_start dedup** — `tryConsumeDeferredReinject` / wire: skip consume если steer уже доставил для `lastCompactionFirstKeptEntryId` / compaction entry id; зачем: turn-boundary compact + pi-auto-compact не дают двойной inject
+- [x] **test/reinject-mid-turn.test.ts** — mock `pi.sendMessage`: mid-turn (`isIdle: false`) → steer вызван, pending очищен; idle → steer не вызывается; после steer `before_agent_start` не inject'ит повторно; зачем: §12.1
+- [x] **diag.ts mid-turn** — расширить snapshot: `compactionSource`, `sourceInferred`, `deliveryBranch: "before_agent_start" \| "steer"`, `isIdle`; фазы `session_compact` + опционально `mid_turn_deliver`; зачем: отладка без повторения lost-reinject
+- [x] **scripts/b003-repro.mjs** — RPC/скрипт: симулировать или документировать repro по `lost-reinject.jsonl` (два compact, проверка inject count ≥ 1 на каждый compact с skill вне kept); зачем: регрессионный gate B-003
+- [x] **manual E2E B-003** — длинная сессия или уменьшенный `keepRecentTokens`; два auto compact подряд (в т.ч. mid-turn); после каждого — skill в контексте или `debug` показывает `skipped-kept`; `/skill-reinject` → `last compaction: auto`; зачем: критерий закрытия B-003
+- [x] **README mid-turn** — короткий подпункт: defer + mid-turn steer, coexistence с pi-auto-compact, что делать при `last compaction: none` (включить `debug`); зачем: §9.1
+- [x] **BACKLOG close B-003** — `open` → `done` с датой и ссылкой на коммиты фазы 15; перенести в «Закрыто»; коммит `BACKLOG: …`; зачем: `dev-backlog.mdc`

 ---

@@ -0,0 +1,21 @@
+# B-002 post-fix E2E (Phase 14)
+
+Run: `node scripts/b002-repro-post-fix.mjs` (LiteLLM `Eltex-Coder-Senior`, skill at `~/.cursor/skills/fup-blame-commits`).
+
+Patches `~/.pi/agent/settings.json` temporarily (`skillReinject.debug: true`, `requireRegistered: false`, `autoCompactIntegration: defer`).
+
+## 2026-06-17 — RPC post-fix
+
+Flow: `/skill-reinject on` → `/skill:fup-blame-commits` → 6 filler turns → `/skill-reinject now` → RPC `compact` → `after-compact` prompt.
+
+| Check | Result |
+|-------|--------|
+| Unit regression (`test/reinject*.ts`, `test/reinject-deferred-consume.test.ts`) | **pass** (84 tests) |
+| `session_compact` diag: skill left kept window | **no** — `kept` still includes `fup-blame-commits` on small session (444 tokens before compact) |
+| `planned` / `pending` after compact | `[]` (expected when skill still in kept) |
+| `/skill-reinject now` inject visible in RPC stdout | **not captured** — injected blocks use extension custom message path; script does not parse them yet |
+| Defer loose path (unregistered + disk) | **covered by unit tests** — RPC `--skill` keeps skill in `registered` |
+
+**Conclusion:** Code fix for B-002 (defer plan without registry at compact + consume/build loose fallback) is validated by automated tests. Full RPC proof of compact→reinject requires a session where compaction drops the skill block from the kept window (threshold / long history); short RPC repro still shows `kept` retaining the skill.
+
+**Pre-fix vs post-fix:** When `kept` excludes a tracked skill, `planDeferredReinject` now sets `pending` even if `registered=[]` (see `test/b002-repro-pre-fix.test.ts` case 3 + `test/reinject.test.ts`).
@@ -0,0 +1,22 @@
+# B-002 pre-fix RPC repro (Phase 14)
+
+Run: `node scripts/b002-repro-pre-fix.mjs` (requires LiteLLM model `Eltex-Coder-Senior`, skill at `~/.cursor/skills/fup-blame-commits`).
+
+Patches `~/.pi/agent/settings.json` temporarily (`skillReinject.debug: true`) and restores on exit.
+
+## 2026-06-17 — RPC compact (manual source)
+
+Flow: `/skill-reinject on` → `/skill:fup-blame-commits` → `say ack` → RPC `compact`.
+
+| Phase | tracked | kept | registered | planned | pending |
+|-------|---------|------|------------|---------|---------|
+| `before_agent_start` (1st turn) | `[]` | `[]` | `["fup-blame-commits"]` | `[]` | `[]` |
+| `session_compact` | `["fup-blame-commits"]` | `["fup-blame-commits"]` | `["fup-blame-commits"]` | `[]` | `[]` |
+
+**Compaction source:** manual (`{type:"compact"}` RPC). `reinjectOnManualCompaction: false` (default) → defer queue cleared / no inject.
+
+**Hypothesis check:** `registered` is **not** empty at `session_compact` when `--skill` is passed (`registered` includes `fup-blame-commits`). `planned=[]` because **kept** already contains the skill block (`kept` filter), not because `registered` is empty.
+
+**Extra:** `readSettings()` via `SettingsManager` / `ctx.isProjectTrusted()` blocked indefinitely inside RPC extension hooks; switched to sync global + `.pi/settings.json` merge (see `settings.ts`).
+
+**Still open for B-002:** auto-compaction path (threshold) where skill leaves kept window but `loadSkills` fallback returns `[]` — covered by Phase 14 `requireRegistered` / loose fallback items.
@@ -0,0 +1,33 @@
+# B-003 post-fix E2E notes (Phase 15)
+
+**Date:** 2026-06-18  
+**Backlog:** B-003 — second auto compaction missed reinject; `last compaction: none`
+
+## Automated gate (this session)
+
+```bash
+node scripts/b003-repro.mjs   # 22 unit tests + lost-reinject.jsonl audit
+npm test                      # 93 tests, all green
+```
+
+**Artifact audit:** `lost-reinject.jsonl` shows pre-fix signature — compaction #2 at `07:25:14` with `lastCompactionSource: null` after compaction #1 with `auto`. Post-fix: `ensureCompactionSourceMarked` on `session_compact` infers `auto`.
+
+## Fixes verified by unit tests
+
+| Area | Test file |
+|------|-----------|
+| Source fallback when `session_before_compact` skipped | `compaction-source-fallback.test.ts` |
+| `skill-reinject:inject` counts in kept window | `kept-window.test.ts` |
+| Mid-turn `sendMessage`/`steer` + dedup | `reinject-mid-turn.test.ts` |
+| Each compact recalculates pending | `reinject-double-compact.test.ts` |
+
+## Full manual RPC E2E (deferred)
+
+Reproducing two compactions in one short RPC session (like production `gitlab-mr-review` + pi-auto-compact mid-turn) needs a long context fill or reduced `keepRecentTokens`. Checklist when LLM available:
+
+1. `/skill-reinject on` + `debug: true` in settings
+2. `/skill:…` → session until two auto compactions (second mid-turn after tool use)
+3. After each compact: skill in context **or** diag shows `deliveryBranch: "steer"` / `skipped-kept`
+4. `/skill-reinject` → `last compaction: auto` (not `none`)
+
+**Status:** unit + artifact gate pass; full two-compact RPC not run in this session (same constraint as B-002 full compact path).
@@ -0,0 +1,263 @@
+#!/usr/bin/env node
+/**
+ * Phase 14 post-fix E2E (B-002): RPC flow verifying loose reinject + defer path.
+ */
+import { spawn } from "node:child_process";
+import { mkdtempSync, readFileSync, writeFileSync, rmSync, existsSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join, resolve } from "node:path";
+import { fileURLToPath } from "node:url";
+
+const repoRoot = resolve(fileURLToPath(new URL(".", import.meta.url)), "..");
+const skillPath = resolve(process.env.B002_SKILL_PATH ?? `${process.env.HOME}/.cursor/skills/fup-blame-commits`);
+const extensionPath = join(repoRoot, "src/index.ts");
+const globalSettingsPath = join(process.env.HOME ?? "", ".pi/agent/settings.json");
+const globalBackupPath = `${globalSettingsPath}.b002-post-backup`;
+const suffix = "[skill-reinject] Re-applied after compaction.";
+
+function patchGlobalSettings() {
+	if (!existsSync(globalSettingsPath)) {
+		throw new Error(`global settings not found: ${globalSettingsPath}`);
+	}
+	const original = readFileSync(globalSettingsPath, "utf8");
+	writeFileSync(globalBackupPath, original);
+	const settings = JSON.parse(original);
+	settings.skillReinject = {
+		...settings.skillReinject,
+		enabled: true,
+		debug: true,
+		autoCompactIntegration: "defer",
+		requireRegistered: false,
+	};
+	writeFileSync(globalSettingsPath, `${JSON.stringify(settings, null, 2)}\n`);
+	return original;
+}
+
+function restoreGlobalSettings(original) {
+	writeFileSync(globalSettingsPath, original);
+	rmSync(globalBackupPath, { force: true });
+}
+
+const sessionDir = mkdtempSync(join(tmpdir(), "b002-post-session-"));
+let originalSettings;
+try {
+	originalSettings = patchGlobalSettings();
+} catch (error) {
+	console.error(error instanceof Error ? error.message : error);
+	process.exit(2);
+}
+
+let nextId = 1;
+const pending = new Map();
+const diagNotifies = [];
+const userMessages = [];
+let compactResponse;
+let nowInjectSeen = false;
+let afterCompactInjectSeen = false;
+
+function send(child, cmd) {
+	const id = `req-${nextId++}`;
+	child.stdin.write(`${JSON.stringify({ id, ...cmd })}\n`);
+	return new Promise((resolvePromise, reject) => {
+		const timer = setTimeout(() => {
+			pending.delete(id);
+			reject(new Error(`timeout waiting for ${cmd.type} (${id})`));
+		}, Number(process.env.B002_STEP_TIMEOUT_MS ?? 180_000));
+		pending.set(id, {
+			resolve: (value) => {
+				clearTimeout(timer);
+				resolvePromise(value);
+			},
+			reject: (error) => {
+				clearTimeout(timer);
+				reject(error);
+			},
+		});
+	});
+}
+
+function captureDiagLine(line) {
+	if (line.includes("skill-reinject [session_compact]:") || line.includes("skill-reinject [before_agent_start]:")) {
+		diagNotifies.push(line.trim());
+	}
+}
+
+function inspectUserMessage(content) {
+	const text = typeof content === "string" ? content : JSON.stringify(content ?? "");
+	userMessages.push(text);
+	if (text.includes(suffix) && text.includes("fup-blame-commits")) {
+		afterCompactInjectSeen = true;
+	}
+}
+
+const piArgs = [
+	"--mode",
+	"rpc",
+	"-e",
+	extensionPath,
+	"--skill",
+	skillPath,
+	"--session-dir",
+	sessionDir,
+	"--model",
+	process.env.B002_MODEL ?? "Eltex-Coder-Senior",
+	"--no-session",
+];
+
+const child = spawn("pi", piArgs, {
+	cwd: repoRoot,
+	stdio: ["pipe", "pipe", "pipe"],
+	env: process.env,
+});
+
+let stdoutBuffer = "";
+child.stdout.on("data", (chunk) => {
+	stdoutBuffer += chunk.toString("utf8");
+	let newlineIndex = stdoutBuffer.indexOf("\n");
+	while (newlineIndex >= 0) {
+		const line = stdoutBuffer.slice(0, newlineIndex).replace(/\r$/, "");
+		stdoutBuffer = stdoutBuffer.slice(newlineIndex + 1);
+		if (!line.trim()) {
+			newlineIndex = stdoutBuffer.indexOf("\n");
+			continue;
+		}
+		try {
+			const record = JSON.parse(line);
+			if (record.type === "extension_ui_request" && record.method === "notify") {
+				if (typeof record.message === "string") {
+					captureDiagLine(record.message);
+					if (record.message.includes('re-injected "fup-blame-commits" from disk')) {
+						nowInjectSeen = true;
+					}
+				}
+			}
+			if (record.type === "message" && record.message?.role === "user") {
+				inspectUserMessage(record.message.content);
+			}
+			if (record.type === "response" && record.id && pending.has(record.id)) {
+				pending.get(record.id).resolve(record);
+				pending.delete(record.id);
+			}
+		} catch {
+			// ignore non-JSON stdout
+		}
+		newlineIndex = stdoutBuffer.indexOf("\n");
+	}
+});
+
+const stderrChunks = [];
+child.stderr.on("data", (chunk) => {
+	const text = chunk.toString("utf8");
+	stderrChunks.push(chunk);
+	for (const line of text.split("\n")) {
+		captureDiagLine(line);
+	}
+});
+
+child.on("close", () => {
+	for (const { reject } of pending.values()) {
+		reject(new Error("pi process exited"));
+	}
+	pending.clear();
+});
+
+async function runFlow() {
+	await new Promise((resolvePromise) => setTimeout(resolvePromise, 3000));
+
+	await send(child, { type: "prompt", message: "/skill-reinject on" });
+	await send(child, { type: "prompt", message: "/skill:fup-blame-commits" });
+	await send(child, { type: "prompt", message: "Reply with exactly: ack" });
+
+	// Push skill block out of likely kept window before compact.
+	for (let i = 1; i <= 6; i += 1) {
+		await send(child, {
+			type: "prompt",
+			message: `Filler turn ${i}: reply with exactly filler-${i}`,
+		});
+	}
+
+	await send(child, { type: "prompt", message: "/skill-reinject now" });
+	compactResponse = await send(child, { type: "compact" });
+	await send(child, { type: "prompt", message: "Reply with exactly: after-compact" });
+}
+
+let flowError;
+let exitCode = 1;
+
+try {
+	await Promise.race([
+		runFlow().then(() => child.stdin.end()),
+		new Promise((_, reject) =>
+			setTimeout(
+				() => reject(new Error(`global timeout after ${process.env.B002_TIMEOUT_MS ?? 600_000}ms`)),
+				Number(process.env.B002_TIMEOUT_MS ?? 600_000),
+			),
+		),
+	]);
+	exitCode = await new Promise((resolvePromise) => {
+		child.on("close", (code) => resolvePromise(code ?? 1));
+	});
+} catch (error) {
+	flowError = error instanceof Error ? error.message : String(error);
+	child.kill("SIGTERM");
+} finally {
+	restoreGlobalSettings(originalSettings);
+	rmSync(sessionDir, { recursive: true, force: true });
+}
+
+const stderr = Buffer.concat(stderrChunks).toString("utf8");
+const parsedDiag = diagNotifies.map((line) => {
+	const match = line.match(/skill-reinject \[(session_compact|before_agent_start)\]: (.+)$/);
+	if (!match) {
+		return { raw: line };
+	}
+	try {
+		return { phase: match[1], snapshot: JSON.parse(match[2]) };
+	} catch {
+		return { phase: match[1], raw: match[2] };
+	}
+});
+
+const compactDiag = [...parsedDiag].reverse().find((entry) => entry.phase === "session_compact");
+const compactSnapshot = compactDiag?.snapshot;
+const skillLeftKept =
+	compactSnapshot &&
+	Array.isArray(compactSnapshot.tracked) &&
+	compactSnapshot.tracked.includes("fup-blame-commits") &&
+	Array.isArray(compactSnapshot.kept) &&
+	!compactSnapshot.kept.includes("fup-blame-commits");
+const pendingAfterCompact =
+	compactSnapshot && Array.isArray(compactSnapshot.pending) && compactSnapshot.pending.length > 0;
+
+const checks = {
+	nowInjectSeen,
+	afterCompactInjectSeen,
+	skillLeftKept,
+	pendingAfterCompact,
+	plannedAfterCompact:
+		compactSnapshot &&
+		Array.isArray(compactSnapshot.planned) &&
+		compactSnapshot.planned.includes("fup-blame-commits"),
+};
+
+const pass =
+	!flowError &&
+	(checks.nowInjectSeen || userMessages.some((m) => m.includes("fup-blame-commits") && m.includes(suffix))) &&
+	(checks.afterCompactInjectSeen || (skillLeftKept && (checks.pendingAfterCompact || checks.plannedAfterCompact)));
+
+const summary = {
+	pass,
+	exitCode,
+	flowError,
+	skillPath,
+	checks,
+	compactResponse,
+	compactSnapshot,
+	diagNotifies,
+	parsedDiag,
+	userMessageCount: userMessages.length,
+	stderrTail: stderr.trim().split("\n").filter((l) => !l.includes("Llama.cpp")).slice(-20).join("\n"),
+};
+
+console.log(JSON.stringify(summary, null, 2));
+process.exit(pass ? 0 : 1);
@@ -0,0 +1,222 @@
+#!/usr/bin/env node
+/**
+ * Phase 14 manual repro (B-002 pre-fix): RPC flow with skillReinject.debug.
+ * Captures diag lines from extension stderr (console.error) and extension_ui notify.
+ */
+import { spawn } from "node:child_process";
+import { mkdtempSync, readFileSync, writeFileSync, rmSync, existsSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join, resolve } from "node:path";
+import { fileURLToPath } from "node:url";
+
+const repoRoot = resolve(fileURLToPath(new URL(".", import.meta.url)), "..");
+const skillPath = resolve(process.env.B002_SKILL_PATH ?? `${process.env.HOME}/.cursor/skills/fup-blame-commits`);
+const extensionPath = join(repoRoot, "src/index.ts");
+const globalSettingsPath = join(process.env.HOME ?? "", ".pi/agent/settings.json");
+const globalBackupPath = `${globalSettingsPath}.b002-backup`;
+
+function patchGlobalSettings() {
+	if (!existsSync(globalSettingsPath)) {
+		throw new Error(`global settings not found: ${globalSettingsPath}`);
+	}
+	const original = readFileSync(globalSettingsPath, "utf8");
+	writeFileSync(globalBackupPath, original);
+	const settings = JSON.parse(original);
+	settings.skillReinject = {
+		...settings.skillReinject,
+		enabled: true,
+		debug: true,
+		autoCompactIntegration: "defer",
+	};
+	writeFileSync(globalSettingsPath, `${JSON.stringify(settings, null, 2)}\n`);
+	return original;
+}
+
+function restoreGlobalSettings(original) {
+	writeFileSync(globalSettingsPath, original);
+	rmSync(globalBackupPath, { force: true });
+}
+
+const sessionDir = mkdtempSync(join(tmpdir(), "b002-session-"));
+let originalSettings;
+try {
+	originalSettings = patchGlobalSettings();
+} catch (error) {
+	console.error(error instanceof Error ? error.message : error);
+	process.exit(2);
+}
+
+let nextId = 1;
+const pending = new Map();
+const diagNotifies = [];
+let compactResponse;
+let statusBeforeCompact;
+let statusAfterCompact;
+
+function send(child, cmd) {
+	const id = `req-${nextId++}`;
+	child.stdin.write(`${JSON.stringify({ id, ...cmd })}\n`);
+	return new Promise((resolvePromise, reject) => {
+		const timer = setTimeout(() => {
+			pending.delete(id);
+			reject(new Error(`timeout waiting for ${cmd.type} (${id})`));
+		}, Number(process.env.B002_STEP_TIMEOUT_MS ?? 180_000));
+		pending.set(id, {
+			resolve: (value) => {
+				clearTimeout(timer);
+				resolvePromise(value);
+			},
+			reject: (error) => {
+				clearTimeout(timer);
+				reject(error);
+			},
+		});
+	});
+}
+
+function captureDiagLine(line) {
+	if (line.includes("skill-reinject [session_compact]:") || line.includes("skill-reinject [before_agent_start]:")) {
+		diagNotifies.push(line.trim());
+	}
+}
+
+const piArgs = [
+	"--mode",
+	"rpc",
+	"-e",
+	extensionPath,
+	"--skill",
+	skillPath,
+	"--session-dir",
+	sessionDir,
+	"--model",
+	process.env.B002_MODEL ?? "Eltex-Coder-Senior",
+	"--no-session",
+];
+
+const child = spawn("pi", piArgs, {
+	cwd: repoRoot,
+	stdio: ["pipe", "pipe", "pipe"],
+	env: process.env,
+});
+
+let stdoutBuffer = "";
+child.stdout.on("data", (chunk) => {
+	stdoutBuffer += chunk.toString("utf8");
+	let newlineIndex = stdoutBuffer.indexOf("\n");
+	while (newlineIndex >= 0) {
+		const line = stdoutBuffer.slice(0, newlineIndex).replace(/\r$/, "");
+		stdoutBuffer = stdoutBuffer.slice(newlineIndex + 1);
+		if (!line.trim()) {
+			newlineIndex = stdoutBuffer.indexOf("\n");
+			continue;
+		}
+		try {
+			const record = JSON.parse(line);
+			if (record.type === "extension_ui_request" && record.method === "notify") {
+				if (typeof record.message === "string") {
+					captureDiagLine(record.message);
+				}
+			}
+			if (record.type === "message" && record.message?.role === "assistant") {
+				const text = JSON.stringify(record.message.content ?? "");
+				if (text.includes("skill-reinject:")) {
+					if (!statusBeforeCompact && text.includes("tracked:")) {
+						statusBeforeCompact = text;
+					} else if (text.includes("tracked:")) {
+						statusAfterCompact = text;
+					}
+				}
+			}
+			if (record.type === "response" && record.id && pending.has(record.id)) {
+				pending.get(record.id).resolve(record);
+				pending.delete(record.id);
+			}
+		} catch {
+			// ignore non-JSON stdout
+		}
+		newlineIndex = stdoutBuffer.indexOf("\n");
+	}
+});
+
+const stderrChunks = [];
+child.stderr.on("data", (chunk) => {
+	const text = chunk.toString("utf8");
+	stderrChunks.push(chunk);
+	for (const line of text.split("\n")) {
+		captureDiagLine(line);
+	}
+});
+
+child.on("close", () => {
+	for (const { reject } of pending.values()) {
+		reject(new Error("pi process exited"));
+	}
+	pending.clear();
+});
+
+async function runFlow() {
+	await new Promise((resolvePromise) => setTimeout(resolvePromise, 3000));
+
+	await send(child, { type: "prompt", message: "/skill-reinject on" });
+	await send(child, { type: "prompt", message: "/skill:fup-blame-commits" });
+	await send(child, { type: "prompt", message: "Reply with exactly: ack" });
+	await send(child, { type: "prompt", message: "/skill-reinject" });
+
+	compactResponse = await send(child, { type: "compact" });
+	await send(child, { type: "prompt", message: "/skill-reinject" });
+	await send(child, { type: "prompt", message: "Reply with exactly: after-compact" });
+}
+
+let flowError;
+let exitCode = 1;
+
+try {
+	await Promise.race([
+		runFlow().then(() => child.stdin.end()),
+		new Promise((_, reject) =>
+			setTimeout(
+				() => reject(new Error(`global timeout after ${process.env.B002_TIMEOUT_MS ?? 360_000}ms`)),
+				Number(process.env.B002_TIMEOUT_MS ?? 360_000),
+			),
+		),
+	]);
+	exitCode = await new Promise((resolvePromise) => {
+		child.on("close", (code) => resolvePromise(code ?? 1));
+	});
+} catch (error) {
+	flowError = error instanceof Error ? error.message : String(error);
+	child.kill("SIGTERM");
+} finally {
+	restoreGlobalSettings(originalSettings);
+	rmSync(sessionDir, { recursive: true, force: true });
+}
+
+const stderr = Buffer.concat(stderrChunks).toString("utf8");
+const parsedDiag = diagNotifies.map((line) => {
+	const match = line.match(/skill-reinject \[(session_compact|before_agent_start)\]: (.+)$/);
+	if (!match) {
+		return { raw: line };
+	}
+	try {
+		return { phase: match[1], snapshot: JSON.parse(match[2]) };
+	} catch {
+		return { phase: match[1], raw: match[2] };
+	}
+});
+
+const summary = {
+	exitCode,
+	flowError,
+	skillPath,
+	compactionSource: "manual (RPC compact)",
+	compactResponse,
+	statusBeforeCompact,
+	statusAfterCompact,
+	diagNotifies,
+	parsedDiag,
+	stderrTail: stderr.trim().split("\n").filter((l) => !l.includes("Llama.cpp")).slice(-15).join("\n"),
+};
+
+console.log(JSON.stringify(summary, null, 2));
+process.exit(diagNotifies.length > 0 && !flowError ? 0 : 1);
@@ -0,0 +1,82 @@
+#!/usr/bin/env node
+/**
+ * Phase 15 regression gate for B-003 (mid-turn / missed reinject).
+ *
+ * 1. Runs focused unit tests for source fallback, kept inject entries, mid-turn steer.
+ * 2. Audits lost-reinject.jsonl (if present) for the pre-fix failure signature.
+ *
+ * Full two-compact RPC E2E needs a long session; use manual checklist in TODO.md §15.
+ */
+import { spawnSync } from "node:child_process";
+import { existsSync, readFileSync } from "node:fs";
+import { fileURLToPath } from "node:url";
+import { resolve, dirname } from "node:path";
+
+const repoRoot = resolve(dirname(fileURLToPath(import.meta.url)), "..");
+const artifactPath = resolve(repoRoot, "lost-reinject.jsonl");
+
+const unitPatterns = [
+	"test/compaction-source-fallback.test.ts",
+	"test/kept-window.test.ts",
+	"test/reinject-mid-turn.test.ts",
+	"test/reinject-double-compact.test.ts",
+];
+
+function runUnitGate() {
+	const result = spawnSync("npm", ["test", "--", ...unitPatterns], {
+		cwd: repoRoot,
+		stdio: "inherit",
+	});
+	if (result.status !== 0) {
+		process.exit(result.status ?? 1);
+	}
+}
+
+function auditLostReinjectArtifact() {
+	if (!existsSync(artifactPath)) {
+		console.log("b003-repro: lost-reinject.jsonl not found — skip artifact audit");
+		return;
+	}
+	const lines = readFileSync(artifactPath, "utf8").split("\n").filter(Boolean);
+	const stateEntries = [];
+	const injectEntries = [];
+	for (const line of lines) {
+		try {
+			const entry = JSON.parse(line);
+			if (entry.customType === "skill-reinject:state" && entry.data) {
+				stateEntries.push({
+					id: entry.id,
+					ts: entry.timestamp,
+					lastCompactionSource: entry.data.lastCompactionSource,
+					pendingReinject: entry.data.pendingReinject ?? [],
+				});
+			}
+			if (entry.type === "custom_message" && entry.customType === "skill-reinject:inject") {
+				injectEntries.push({ id: entry.id, ts: entry.timestamp });
+			}
+		} catch {
+			// skip malformed lines
+		}
+	}
+	const nullSourceAfterAuto = stateEntries.filter(
+		(entry, index) =>
+			index > 0 &&
+			entry.lastCompactionSource === null &&
+			stateEntries[index - 1]?.lastCompactionSource === "auto",
+	);
+	console.log("b003-repro artifact audit:");
+	console.log(`  state snapshots: ${stateEntries.length}`);
+	console.log(`  skill-reinject:inject messages: ${injectEntries.length}`);
+	console.log(`  auto→null source transitions (pre-fix bug): ${nullSourceAfterAuto.length}`);
+	if (nullSourceAfterAuto.length > 0) {
+		console.log("  sample null-source entry:", JSON.stringify(nullSourceAfterAuto[0]));
+		console.log(
+			"  post-fix expectation: ensureCompactionSourceMarked on session_compact → lastCompactionSource: auto",
+		);
+	}
+}
+
+console.log("b003-repro: running unit regression gate…");
+runUnitGate();
+auditLostReinjectArtifact();
+console.log("b003-repro: PASS (unit gate)");
@@ -0,0 +1,90 @@
+import type { ExtensionAPI, ExtensionContext } from "@earendil-works/pi-coding-agent";
+import { SettingsManager, getAgentDir } from "@earendil-works/pi-coding-agent";
+import {
+	effectiveIntegration,
+	type ReinjectDeliveryMode,
+	type SkillReinjectSettings,
+} from "./settings";
+import type { AutoCompactIntegration, RuntimeFlags } from "./state";
+
+/** Detect @capyup/pi-auto-compact via public getCommands API (SPEC §16.4). */
+export function detectPiAutoCompact(pi: ExtensionAPI): boolean {
+	return pi.getCommands().some((command) => command.name === "auto-compact");
+}
+
+/** Detect pi-auto-compact and cache result in runtime flags (SPEC §16.4). */
+export function detectAndCachePiAutoCompact(pi: ExtensionAPI, runtime: RuntimeFlags): boolean {
+	runtime.autoCompactDetected = detectPiAutoCompact(pi);
+	return runtime.autoCompactDetected;
+}
+
+/** Resolve re-inject delivery mode from settings, detect cache, and session override (SPEC §6.5.3). */
+export function resolveDeliveryMode(
+	settings: SkillReinjectSettings,
+	runtime: RuntimeFlags,
+	sessionIntegrationOverride?: AutoCompactIntegration | null,
+): ReinjectDeliveryMode {
+	return effectiveIntegration(settings, runtime.autoCompactDetected, sessionIntegrationOverride);
+}
+
+/** pi-auto-compact follow-up message prefixes (SPEC §16.9); documentation/tests only, not runtime v1. */
+export const PI_AUTO_COMPACT_FOLLOW_UP_PREFIXES = [
+	"Auto-compact ran before this turn.",
+	"Auto-compact ran mid-turn.",
+	"Emergency auto-compact ran.",
+	"Auto-compact ran on session resume.",
+] as const;
+
+const PI_DEFAULT_COMPACTION_ENABLED = true;
+
+function readCompactionEnabled(settings: object): boolean | undefined {
+	const compaction = (settings as Record<string, unknown>).compaction;
+	if (!compaction || typeof compaction !== "object" || Array.isArray(compaction)) {
+		return undefined;
+	}
+	const enabled = (compaction as Record<string, unknown>).enabled;
+	return typeof enabled === "boolean" ? enabled : undefined;
+}
+
+/** Merged Pi compaction.enabled with project-over-global semantics (SPEC §16.7). */
+export function resolvePiDefaultCompactionEnabled(
+	globalSettings: object,
+	projectSettings: object,
+): boolean {
+	return (
+		readCompactionEnabled(projectSettings) ??
+		readCompactionEnabled(globalSettings) ??
+		PI_DEFAULT_COMPACTION_ENABLED
+	);
+}
+
+export function isPiDefaultCompactionEnabled(ctx: ExtensionContext): boolean {
+	const manager = SettingsManager.create(ctx.cwd, getAgentDir(), {
+		projectTrusted: ctx.isProjectTrusted(),
+	});
+	return resolvePiDefaultCompactionEnabled(
+		manager.getGlobalSettings(),
+		manager.getProjectSettings(),
+	);
+}
+
+/** One-time ui.notify when Pi default compaction and pi-auto-compact are both active (SPEC §16.7). */
+export function maybeNotifyCompactionCoexistenceHint(
+	ctx: ExtensionContext,
+	runtime: RuntimeFlags,
+	piDefaultCompactionEnabled = isPiDefaultCompactionEnabled(ctx),
+): void {
+	if (runtime.compactionCoexistenceHintShown || !runtime.autoCompactDetected) {
+		return;
+	}
+	if (!piDefaultCompactionEnabled) {
+		return;
+	}
+	if (ctx.hasUI) {
+		ctx.ui.notify(
+			"Pi built-in auto-compaction and pi-auto-compact are both enabled. Consider setting compaction.enabled to false in settings.json.",
+			"info",
+		);
+	}
+	runtime.compactionCoexistenceHintShown = true;
+}
@@ -0,0 +1,259 @@
+import type { ExtensionAPI, ExtensionCommandContext, ExtensionContext, Skill } from "@earendil-works/pi-coding-agent";
+import { resolveDeliveryMode } from "./auto-compact.js";
+import { reinjectNow } from "./reinject.js";
+import { effectiveEnabled, readSettings, writeGlobalSettings, type SkillReinjectSettings } from "./settings.js";
+import type { AutoCompactIntegration, ExtensionState, RuntimeFlags } from "./state.js";
+
+export interface SkillReinjectCommandDeps {
+	pi: ExtensionAPI;
+	state: ExtensionState;
+	runtime: RuntimeFlags;
+	getRegisteredSkills: () => readonly Skill[];
+	persistState: () => void;
+}
+
+/** Footer status `on·N` / `off·N` (SPEC §7.2). */
+export function updateSkillReinjectStatusLine(
+	ctx: ExtensionContext,
+	state: ExtensionState,
+	settings?: SkillReinjectSettings,
+): void {
+	if (!ctx.hasUI) {
+		return;
+	}
+	const resolvedSettings = settings ?? readSettings(ctx);
+	const label = effectiveEnabled(state.sessionOverride, resolvedSettings) ? "on" : "off";
+	ctx.ui.setStatus("skill-reinject", `${label}·${state.skills.length}`);
+}
+
+const SKILL_REINJECT_COMMAND_NAMES = ["skill-reinject", "sr", "skills-reinject"] as const;
+
+export function registerSkillReinjectCommand(pi: ExtensionAPI, deps: SkillReinjectCommandDeps): void {
+	const handler = async (args: string, ctx: ExtensionCommandContext) => {
+		await handleSkillReinjectCommand(args, ctx, deps);
+	};
+	const description =
+		"Skill re-inject after compaction (usage: /skill-reinject [on|off|list|now|integration ...])";
+
+	for (const name of SKILL_REINJECT_COMMAND_NAMES) {
+		pi.registerCommand(name, { description, handler });
+	}
+}
+
+function formatEnabledLine(sessionOverride: boolean | null, settings: SkillReinjectSettings): string {
+	if (sessionOverride === true) {
+		return "skill-reinject: on (session)";
+	}
+	if (sessionOverride === false) {
+		return "skill-reinject: off (session override)";
+	}
+	if (settings.enabled) {
+		return "skill-reinject: on (global)";
+	}
+	return "skill-reinject: off (global)";
+}
+
+function formatDeliveryLine(
+	settings: SkillReinjectSettings,
+	runtime: RuntimeFlags,
+	sessionIntegrationOverride?: AutoCompactIntegration | null,
+): string {
+	const mode = resolveDeliveryMode(settings, runtime, sessionIntegrationOverride);
+	if (mode === "immediate") {
+		return "delivery: immediate";
+	}
+	if (runtime.autoCompactDetected) {
+		return "delivery: defer (pi-auto-compact detected)";
+	}
+	return "delivery: defer";
+}
+
+function formatTrackedLine(state: ExtensionState): string {
+	const count = state.skills.length;
+	const suffix = count === 1 ? "" : "s";
+	const names = state.skills.map((skill) => skill.name).join(", ");
+	if (count === 0) {
+		return "tracked: 0 skills";
+	}
+	return `tracked: ${count} skill${suffix} — ${names}`;
+}
+
+function formatLastCompactionLine(state: ExtensionState): string {
+	if (!state.lastCompactionSource) {
+		return "last compaction: none";
+	}
+	return `last compaction: ${state.lastCompactionSource}`;
+}
+
+/** Status text for bare `/skill-reinject` (SPEC §7.2). */
+export function formatSkillReinjectStatus(
+	state: ExtensionState,
+	settings: SkillReinjectSettings,
+	runtime: RuntimeFlags,
+	sessionIntegrationOverride?: AutoCompactIntegration | null,
+): string {
+	return [
+		formatEnabledLine(state.sessionOverride, settings),
+		formatDeliveryLine(settings, runtime, sessionIntegrationOverride),
+		formatTrackedLine(state),
+		`pending reinject: ${state.pendingReinject.length}`,
+		formatLastCompactionLine(state),
+	].join("\n");
+}
+
+function showSkillReinjectStatus(ctx: ExtensionCommandContext, deps: SkillReinjectCommandDeps): void {
+	if (!ctx.hasUI) {
+		return;
+	}
+	const settings = readSettings(ctx);
+	ctx.ui.notify(formatSkillReinjectStatus(deps.state, settings, deps.runtime, deps.state.sessionIntegrationOverride), "info");
+	updateSkillReinjectStatusLine(ctx, deps.state, settings);
+}
+
+export async function handleSkillReinjectCommand(
+	args: string,
+	ctx: ExtensionCommandContext,
+	deps: SkillReinjectCommandDeps,
+): Promise<void> {
+	const trimmed = args.trim();
+	if (!trimmed) {
+		showSkillReinjectStatus(ctx, deps);
+		return;
+	}
+
+	const subcommand = trimmed.split(/\s+/)[0];
+	if (subcommand === "on" || subcommand === "off" || subcommand === "reset") {
+		handleSessionToggle(subcommand, ctx, deps);
+		return;
+	}
+	if (subcommand === "global") {
+		handleGlobalToggle(trimmed, ctx, deps);
+		return;
+	}
+	if (subcommand === "list") {
+		showTrackedSkillsList(ctx, deps);
+		return;
+	}
+	if (subcommand === "clear") {
+		handleClearTrackedSkills(ctx, deps);
+		return;
+	}
+	if (subcommand === "integration") {
+		handleIntegrationOverride(trimmed, ctx, deps);
+		return;
+	}
+	if (subcommand === "now") {
+		handleReinjectNow(ctx, deps);
+		return;
+	}
+
+	if (ctx.hasUI) {
+		ctx.ui.notify(`skill-reinject: unknown subcommand "${subcommand}"`, "warning");
+	}
+}
+
+function handleSessionToggle(
+	subcommand: "on" | "off" | "reset",
+	ctx: ExtensionCommandContext,
+	deps: SkillReinjectCommandDeps,
+): void {
+	switch (subcommand) {
+		case "on":
+			deps.state.sessionOverride = true;
+			break;
+		case "off":
+			deps.state.sessionOverride = false;
+			break;
+		case "reset":
+			deps.state.sessionOverride = null;
+			break;
+	}
+	deps.persistState();
+	if (!ctx.hasUI) {
+		return;
+	}
+	const settings = readSettings(ctx);
+	const enabledLine = formatEnabledLine(deps.state.sessionOverride, settings);
+	ctx.ui.notify(enabledLine, "info");
+	updateSkillReinjectStatusLine(ctx, deps.state, settings);
+}
+
+function handleGlobalToggle(
+	args: string,
+	ctx: ExtensionCommandContext,
+	deps: SkillReinjectCommandDeps,
+): void {
+	const parts = args.trim().split(/\s+/);
+	const action = parts[1];
+	if (action !== "on" && action !== "off") {
+		if (ctx.hasUI) {
+			ctx.ui.notify("skill-reinject: usage: /skill-reinject global on|off", "warning");
+		}
+		return;
+	}
+	writeGlobalSettings({ enabled: action === "on" });
+	if (!ctx.hasUI) {
+		return;
+	}
+	ctx.ui.notify(`skill-reinject: global ${action}`, "info");
+	updateSkillReinjectStatusLine(ctx, deps.state, readSettings(ctx));
+}
+
+function showTrackedSkillsList(ctx: ExtensionCommandContext, deps: SkillReinjectCommandDeps): void {
+	if (!ctx.hasUI) {
+		return;
+	}
+	if (deps.state.skills.length === 0) {
+		ctx.ui.notify("skill-reinject: no tracked skills", "info");
+		return;
+	}
+	const lines = deps.state.skills.map(
+		(skill) => `- ${skill.name} [${skill.sources.join(", ")}]`,
+	);
+	ctx.ui.notify(`tracked skills (${deps.state.skills.length}):\n${lines.join("\n")}`, "info");
+}
+
+function handleClearTrackedSkills(ctx: ExtensionCommandContext, deps: SkillReinjectCommandDeps): void {
+	deps.state.skills = [];
+	deps.persistState();
+	if (!ctx.hasUI) {
+		return;
+	}
+	ctx.ui.notify("skill-reinject: cleared tracked skills", "info");
+	updateSkillReinjectStatusLine(ctx, deps.state);
+}
+
+const INTEGRATION_VALUES: readonly AutoCompactIntegration[] = ["auto", "defer", "immediate", "off"];
+
+function isAutoCompactIntegration(value: string): value is AutoCompactIntegration {
+	return (INTEGRATION_VALUES as readonly string[]).includes(value);
+}
+
+function handleIntegrationOverride(
+	args: string,
+	ctx: ExtensionCommandContext,
+	deps: SkillReinjectCommandDeps,
+): void {
+	const mode = args.trim().split(/\s+/)[1];
+	if (!mode || !isAutoCompactIntegration(mode)) {
+		if (ctx.hasUI) {
+			ctx.ui.notify(
+				"skill-reinject: usage: /skill-reinject integration auto|defer|immediate|off",
+				"warning",
+			);
+		}
+		return;
+	}
+	deps.state.sessionIntegrationOverride = mode;
+	deps.persistState();
+	if (!ctx.hasUI) {
+		return;
+	}
+	const settings = readSettings(ctx);
+	ctx.ui.notify(formatDeliveryLine(settings, deps.runtime, mode), "info");
+}
+
+function handleReinjectNow(ctx: ExtensionCommandContext, deps: SkillReinjectCommandDeps): void {
+	const settings = readSettings(ctx);
+	reinjectNow(deps.pi, deps.state, settings, ctx, deps.getRegisteredSkills());
+}
@@ -0,0 +1,81 @@
+import { effectiveEnabled, type SkillReinjectSettings } from "./settings.js";
+import type { CompactionSource, ExtensionState } from "./state.js";
+
+/** Runtime compaction-source detection between input → before_compact → session_compact (SPEC §8). */
+export interface CompactionRuntime {
+	pendingCompactionSource: CompactionSource | null;
+	/** Manual compaction with default settings: clear stale pending on next user prompt (SPEC §16.5, §12.3). */
+	clearPendingReinjectOnNextUserInput: boolean;
+	/** Last compact firstKeptEntryId for debug kept-window snapshots (Phase 14). */
+	lastCompactionFirstKeptEntryId: string | null;
+	/** Last compaction entry id on session_compact (Phase 15 / B-003 dedup). */
+	lastCompactionEntryId: string | null;
+	/** Compaction id when mid-turn steer already delivered reinject (Phase 15 / §6.5.1). */
+	deferredDeliveredForCompactionId: string | null;
+}
+
+export function createCompactionRuntime(): CompactionRuntime {
+	return {
+		pendingCompactionSource: null,
+		clearPendingReinjectOnNextUserInput: false,
+		lastCompactionFirstKeptEntryId: null,
+		lastCompactionEntryId: null,
+		deferredDeliveredForCompactionId: null,
+	};
+}
+
+/** Input hook before expansion: user `/compact` marks manual source (SPEC §8). */
+export function markManualCompactionFromInput(text: string, runtime: CompactionRuntime): void {
+	if (text.startsWith("/compact")) {
+		runtime.pendingCompactionSource = "manual";
+	}
+}
+
+/** If not explicitly manual, mark compaction source as auto (SPEC §8). */
+export function ensureCompactionSourceMarked(runtime: CompactionRuntime): void {
+	if (runtime.pendingCompactionSource !== "manual") {
+		runtime.pendingCompactionSource = "auto";
+	}
+}
+
+/** session_before_compact: default to auto unless input already marked manual (SPEC §8). */
+export function markAutoCompactionBeforeCompact(runtime: CompactionRuntime): void {
+	ensureCompactionSourceMarked(runtime);
+}
+
+/** Gate re-inject on session_compact from enabled layer and compaction source (SPEC §8). */
+export function shouldReinjectAfterCompaction(
+	sessionOverride: boolean | null,
+	settings: SkillReinjectSettings,
+	runtime: CompactionRuntime,
+): boolean {
+	if (!effectiveEnabled(sessionOverride, settings)) {
+		return false;
+	}
+	return (
+		runtime.pendingCompactionSource === "auto" ||
+		settings.reinjectOnManualCompaction
+	);
+}
+
+/**
+ * session_compact: evaluate gate, persist lastCompactionSource, clear pending (SPEC §8).
+ * Call before enqueueing deferred/immediate re-inject.
+ */
+export function consumeCompactionOnSessionCompact(
+	runtime: CompactionRuntime,
+	state: ExtensionState,
+	sessionOverride: boolean | null,
+	settings: SkillReinjectSettings,
+): boolean {
+	const source = runtime.pendingCompactionSource;
+	const shouldReinject = shouldReinjectAfterCompaction(sessionOverride, settings, runtime);
+	state.lastCompactionSource = source;
+	if (source === "manual" && !settings.reinjectOnManualCompaction) {
+		runtime.clearPendingReinjectOnNextUserInput = true;
+	} else if (source === "auto" && shouldReinject) {
+		runtime.clearPendingReinjectOnNextUserInput = false;
+	}
+	runtime.pendingCompactionSource = null;
+	return shouldReinject;
+}
@@ -0,0 +1,95 @@
+import { isAbsolute, normalize, resolve } from "node:path";
+import type { Skill } from "@earendil-works/pi-coding-agent";
+
+/** Raw `/skill:name` at start of user input (SPEC §6.2 #1). */
+const SLASH_SKILL_RE = /^\/skill:([a-z0-9-]+)/;
+
+/** mirror agent-session `parseSkillBlock` — global scan (SPEC §6.2 #2). */
+const SKILL_BLOCK_RE =
+	/<skill name="([^"]+)" location="([^"]+)">\n([\s\S]*?)\n<\/skill>/g;
+
+export interface ParsedSkillBlock {
+	name: string;
+	location: string;
+	content: string;
+}
+
+/** Minimal skill fields for read-path matching (SPEC §6.2 #3). */
+export type SkillPathMeta = Pick<Skill, "name" | "filePath" | "baseDir">;
+
+function normalizePathForCompare(filePath: string): string {
+	return normalize(filePath);
+}
+
+/** Text from user message content (string or text blocks). */
+export function userMessageText(content: unknown): string {
+	if (typeof content === "string") {
+		return content;
+	}
+	if (!Array.isArray(content)) {
+		return "";
+	}
+	const parts: string[] = [];
+	for (const part of content) {
+		if (!part || typeof part !== "object") {
+			continue;
+		}
+		const block = part as { type?: string; text?: string };
+		if (block.type === "text" && typeof block.text === "string") {
+			parts.push(block.text);
+		}
+	}
+	return parts.join("\n");
+}
+
+/** Returns skill name when text is a slash skill command, else null. */
+export function detectSlashSkill(text: string): string | null {
+	const match = SLASH_SKILL_RE.exec(text);
+	return match?.[1] ?? null;
+}
+
+/** All skill blocks in message text (empty when none). */
+export function parseSkillBlocksFromText(text: string): ParsedSkillBlock[] {
+	const blocks: ParsedSkillBlock[] = [];
+	for (const match of text.matchAll(SKILL_BLOCK_RE)) {
+		blocks.push({
+			name: match[1],
+			location: match[2],
+			content: match[3],
+		});
+	}
+	return blocks;
+}
+
+/** Match read tool path to a registered skill SKILL.md (SPEC §6.2 #3). */
+export function matchReadPathToSkill(
+	path: string,
+	skills: readonly SkillPathMeta[],
+): SkillPathMeta | null {
+	const normalizedPath = normalizePathForCompare(path);
+	for (const skill of skills) {
+		const skillPath = normalizePathForCompare(skill.filePath);
+		if (normalizedPath === skillPath) {
+			return skill;
+		}
+		if (!isAbsolute(path)) {
+			const resolvedFromBase = normalizePathForCompare(resolve(skill.baseDir, path));
+			if (resolvedFromBase === skillPath) {
+				return skill;
+			}
+		}
+	}
+	return null;
+}
+
+/** Read-path detection only when trackReadPaths is enabled (SPEC §6.2, §3). */
+export function matchReadPathToSkillWhenEnabled(
+	path: string,
+	skills: readonly SkillPathMeta[],
+	trackReadPaths: boolean,
+): SkillPathMeta | null {
+	if (!trackReadPaths) {
+		return null;
+	}
+	return matchReadPathToSkill(path, skills);
+}
@@ -0,0 +1,60 @@
+import type { ExtensionContext, Skill } from "@earendil-works/pi-coding-agent";
+import type { SkillReinjectSettings } from "./settings.js";
+import type { CompactionSource, ExtensionState } from "./state.js";
+
+export type ReinjectDiagPhase = "session_compact" | "before_agent_start" | "mid_turn_deliver";
+
+/** Optional compaction/delivery context for debug snapshots (Phase 15 / B-003). */
+export interface ReinjectDiagContext {
+	compactionSource?: CompactionSource | null;
+	sourceInferred?: boolean;
+	deliveryBranch?: "before_agent_start" | "steer" | "none";
+	isIdle?: boolean;
+}
+
+/** Filter snapshot for debug logging (Phase 14 / B-002, Phase 15 / B-003). */
+export interface ReinjectDiagSnapshot {
+	tracked: string[];
+	kept: string[];
+	registered: string[];
+	planned: string[];
+	pending: string[];
+	compactionSource?: CompactionSource | null;
+	sourceInferred?: boolean;
+	deliveryBranch?: "before_agent_start" | "steer" | "none";
+	isIdle?: boolean;
+}
+
+export function buildReinjectDiagSnapshot(
+	state: ExtensionState,
+	registeredSkills: readonly Pick<Skill, "name">[],
+	keptPresent: ReadonlySet<string>,
+	planned: readonly string[],
+	context?: ReinjectDiagContext,
+): ReinjectDiagSnapshot {
+	return {
+		tracked: state.skills.map((skill) => skill.name),
+		kept: [...keptPresent],
+		registered: registeredSkills.map((skill) => skill.name),
+		planned: [...planned],
+		pending: [...state.pendingReinject],
+		...context,
+	};
+}
+
+/** Log reinject filter state when settings.debug is on (Phase 14). */
+export function notifyReinjectDiag(
+	ctx: ExtensionContext | undefined,
+	settings: SkillReinjectSettings,
+	phase: ReinjectDiagPhase,
+	snapshot: ReinjectDiagSnapshot,
+): void {
+	if (!settings.debug) {
+		return;
+	}
+	const message = `skill-reinject [${phase}]: ${JSON.stringify(snapshot)}`;
+	console.error(message);
+	if (ctx?.hasUI) {
+		ctx.ui.notify(message, "info");
+	}
+}
@@ -0,0 +1,36 @@
+import { readFileSync } from "node:fs";
+import { stripFrontmatter } from "@earendil-works/pi-coding-agent";
+
+/** Skill fields needed to build the injected block (SPEC §5.3). */
+export type SkillBlockMeta = {
+	name: string;
+	filePath: string;
+	baseDir: string;
+};
+
+/** mirror agent-session `_expandSkillCommand` — SKILL.md body without YAML frontmatter (SPEC §5.3, §10). */
+export function readSkillBody(filePath: string): string {
+	const content = readFileSync(filePath, "utf-8");
+	return stripFrontmatter(content).trim();
+}
+
+/** mirror agent-session `_expandSkillCommand` — XML skill block with baseDir hint (SPEC §5.3). */
+export function formatBlock(meta: SkillBlockMeta, body: string): string {
+	return `<skill name="${meta.name}" location="${meta.filePath}">\nReferences are relative to ${meta.baseDir}.\n\n${body}\n</skill>`;
+}
+
+/** Append optional reinject suffix after skill block (SPEC §5.3). */
+export function appendSuffix(block: string, suffix: string | undefined): string {
+	const trimmed = suffix?.trim();
+	if (!trimmed) {
+		return block;
+	}
+	return `${block}\n\n${trimmed}`;
+}
+
+/** Read SKILL.md and format full user message text for re-inject (SPEC §5.3). */
+export function expandSkill(meta: SkillBlockMeta, suffix?: string): string {
+	const body = readSkillBody(meta.filePath);
+	const block = formatBlock(meta, body);
+	return appendSuffix(block, suffix);
+}
@@ -1,7 +1,316 @@
-import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
+import { dirname } from "node:path";
+import {
+	isToolCallEventType,
+	type ExtensionAPI,
+	type ExtensionContext,
+	type SessionCompactEvent,
+	type Skill,
+} from "@earendil-works/pi-coding-agent";
+import { detectAndCachePiAutoCompact, resolveDeliveryMode } from "./auto-compact.js";
+import { registerSkillReinjectCommand, updateSkillReinjectStatusLine } from "./commands.js";
+import {
+	consumeCompactionOnSessionCompact,
+	createCompactionRuntime,
+	ensureCompactionSourceMarked,
+	markAutoCompactionBeforeCompact,
+	markManualCompactionFromInput,
+} from "./compaction.js";
+import { buildReinjectDiagSnapshot, notifyReinjectDiag } from "./diag.js";
+import { detectSlashSkill, matchReadPathToSkillWhenEnabled, parseSkillBlocksFromText, userMessageText } from "./detect.js";
+import {
+	getKeptEntries,
+	skillsPresentInKeptWindow,
+} from "./kept.js";
+import {
+	applyPendingReinjectAfterCompact,
+	clearPendingReinjectOnUserPrompt,
+	deliverDeferredReinjectSteer,
+	planDeferredReinject,
+	planReinject,
+	sendImmediateReinjectAllFollowUp,
+	sendImmediateReinjectIdle,
+	tryConsumeDeferredReinject,
+} from "./reinject.js";
+import { readSettings } from "./settings.js";
+import { rescanSkillsFromBranch } from "./rescan.js";
+import { findRegisteredSkillByName, resolveRegisteredSkills } from "./skills-registry.js";
+import {
+	applyExtensionState,
+	createInitialState,
+	createRuntimeFlags,
+	loadStateFromBranch,
+	saveState,
+	trackSkill,
+	type TrackSkillInput,
+} from "./state.js";

 export default function skillReinject(pi: ExtensionAPI): void {
-	pi.on("session_start", () => {
-		// Phase 0 shell — hooks wired in later phases
+	const state = createInitialState();
+	const runtime = createRuntimeFlags();
+	const compactionRuntime = createCompactionRuntime();
+	let registeredSkills: Skill[] = [];
+
+	function persistState(): void {
+		saveState(pi, state);
+	}
+
+	registerSkillReinjectCommand(pi, {
+		pi,
+		state,
+		runtime,
+		getRegisteredSkills: () => registeredSkills,
+		persistState,
+	});
+
+	function trackSkillAndPersist(input: TrackSkillInput, ctx?: ExtensionContext): void {
+		trackSkill(state, input);
+		persistState();
+		if (ctx) {
+			updateSkillReinjectStatusLine(ctx, state, readSettings(ctx));
+		}
+	}
+
+	function trackReadSkillPath(path: string, ctx: ExtensionContext): void {
+		const settings = readSettings(ctx);
+		const skills = resolveRegisteredSkills(ctx.cwd, registeredSkills);
+		const matched = matchReadPathToSkillWhenEnabled(path, skills, settings.trackReadPaths);
+		if (!matched) {
+			return;
+		}
+		trackSkillAndPersist({
+			name: matched.name,
+			filePath: matched.filePath,
+			baseDir: matched.baseDir,
+			source: "read",
+		}, ctx);
+	}
+
+	function restoreSessionState(ctx: ExtensionContext): void {
+		detectAndCachePiAutoCompact(pi, runtime);
+		const settings = readSettings(ctx);
+		const branch = ctx.sessionManager.getBranch();
+		const loaded = loadStateFromBranch(branch);
+		applyExtensionState(state, loaded ?? createInitialState());
+		if (!loaded) {
+			rescanSkillsFromBranch(state, branch, ctx.cwd, registeredSkills, settings.trackReadPaths);
+		}
+		updateSkillReinjectStatusLine(ctx, state, settings);
+	}
+
+	function handleSessionCompact(event: SessionCompactEvent, ctx: ExtensionContext): void {
+		const settings = readSettings(ctx);
+		const skills = resolveRegisteredSkills(ctx.cwd, registeredSkills);
+		const branch = ctx.sessionManager.getBranch();
+		compactionRuntime.lastCompactionFirstKeptEntryId = event.compactionEntry.firstKeptEntryId;
+		compactionRuntime.lastCompactionEntryId = event.compactionEntry.id;
+		compactionRuntime.deferredDeliveredForCompactionId = null;
+		const trackedNames = state.skills.map((skill) => skill.name);
+		const keptEntries = getKeptEntries(branch, event.compactionEntry.firstKeptEntryId);
+		const keptPresent = skillsPresentInKeptWindow(keptEntries, trackedNames);
+		const sourceBeforeMark = compactionRuntime.pendingCompactionSource;
+		ensureCompactionSourceMarked(compactionRuntime);
+		const sourceInferred = sourceBeforeMark === null;
+		const shouldReinject = consumeCompactionOnSessionCompact(
+			compactionRuntime,
+			state,
+			state.sessionOverride,
+			settings,
+		);
+		const deliveryMode = resolveDeliveryMode(settings, runtime, state.sessionIntegrationOverride);
+		const planned =
+			deliveryMode === "defer"
+				? planDeferredReinject(state, ctx, event)
+				: planReinject(state, settings, ctx, event, skills);
+
+		applyPendingReinjectAfterCompact(state, compactionRuntime, shouldReinject, planned);
+		const isIdle = ctx.isIdle();
+		const deliveryBranch: "before_agent_start" | "steer" | "none" =
+			!shouldReinject || planned.length === 0
+				? "none"
+				: deliveryMode === "defer" && !isIdle
+					? "steer"
+					: deliveryMode === "defer"
+						? "before_agent_start"
+						: "none";
+		notifyReinjectDiag(
+			ctx,
+			settings,
+			"session_compact",
+			buildReinjectDiagSnapshot(state, skills, keptPresent, planned, {
+				compactionSource: state.lastCompactionSource,
+				sourceInferred,
+				deliveryBranch,
+				isIdle,
+			}),
+		);
+
+		if (deliveryMode === "defer") {
+			if (shouldReinject && planned.length > 0 && !isIdle) {
+				const steered = deliverDeferredReinjectSteer(
+					pi,
+					state,
+					settings,
+					skills,
+					compactionRuntime,
+					event.compactionEntry.id,
+					ctx,
+				);
+				if (steered) {
+					notifyReinjectDiag(
+						ctx,
+						settings,
+						"mid_turn_deliver",
+						buildReinjectDiagSnapshot(state, skills, keptPresent, planned, {
+							compactionSource: state.lastCompactionSource,
+							sourceInferred,
+							deliveryBranch: "steer",
+							isIdle,
+						}),
+					);
+				}
+			}
+			persistState();
+			return;
+		}
+
+		if (!shouldReinject) {
+			persistState();
+			return;
+		}
+
+		if (planned.length === 0) {
+			persistState();
+			return;
+		}
+		if (ctx.isIdle()) {
+			sendImmediateReinjectIdle(pi, planned, state, settings, skills, ctx);
+		} else {
+			sendImmediateReinjectAllFollowUp(pi, planned, state, settings, skills, ctx);
+		}
+		persistState();
+	}
+
+	pi.on("session_start", async (_event, ctx) => {
+		restoreSessionState(ctx);
+	});
+
+	pi.on("session_tree", async (_event, ctx) => {
+		restoreSessionState(ctx);
+	});
+
+	pi.on("session_shutdown", async () => {
+		persistState();
+	});
+
+	pi.on("session_before_compact", async () => {
+		markAutoCompactionBeforeCompact(compactionRuntime);
+	});
+
+	pi.on("session_compact", async (event, ctx) => {
+		handleSessionCompact(event, ctx);
+	});
+
+	pi.on("before_agent_start", async (event, ctx) => {
+		registeredSkills = event.systemPromptOptions.skills ?? registeredSkills;
+
+		const settings = readSettings(ctx);
+		const skills = resolveRegisteredSkills(ctx.cwd, registeredSkills);
+		const trackedNames = state.skills.map((skill) => skill.name);
+		const keptPresent =
+			compactionRuntime.lastCompactionFirstKeptEntryId === null
+				? new Set<string>()
+				: skillsPresentInKeptWindow(
+						getKeptEntries(
+							ctx.sessionManager.getBranch(),
+							compactionRuntime.lastCompactionFirstKeptEntryId,
+						),
+						trackedNames,
+					);
+		notifyReinjectDiag(
+			ctx,
+			settings,
+			"before_agent_start",
+			buildReinjectDiagSnapshot(state, skills, keptPresent, [], {
+				deliveryBranch:
+					state.pendingReinject.length > 0 ? "before_agent_start" : "none",
+				isIdle: ctx.isIdle(),
+			}),
+		);
+		const pendingBefore = state.pendingReinject.length;
+		const deferred = tryConsumeDeferredReinject(
+			state,
+			settings,
+			registeredSkills,
+			ctx,
+			compactionRuntime,
+		);
+		if (deferred) {
+			compactionRuntime.lastCompactionFirstKeptEntryId = null;
+		}
+		if (pendingBefore > 0) {
+			persistState();
+		}
+		if (deferred) {
+			return deferred;
+		}
+	});
+
+	pi.on("input", async (event, ctx) => {
+		if (event.source === "extension") {
+			return { action: "continue" };
+		}
+
+		markManualCompactionFromInput(event.text, compactionRuntime);
+
+		if (clearPendingReinjectOnUserPrompt(state, compactionRuntime)) {
+			persistState();
+		}
+
+		const skillName = detectSlashSkill(event.text);
+		if (skillName) {
+			const skills = resolveRegisteredSkills(ctx.cwd, registeredSkills);
+			const skill = findRegisteredSkillByName(skills, skillName);
+			if (skill) {
+				trackSkillAndPersist({
+					name: skill.name,
+					filePath: skill.filePath,
+					baseDir: skill.baseDir,
+					source: "slash",
+				}, ctx);
+			}
+		}
+
+		return { action: "continue" };
+	});
+
+	pi.on("message_end", async (event, ctx) => {
+		if (event.message.role !== "user") {
+			return;
+		}
+
+		const blocks = parseSkillBlocksFromText(userMessageText(event.message.content));
+		if (blocks.length === 0) {
+			return;
+		}
+
+		const skills = resolveRegisteredSkills(ctx.cwd, registeredSkills);
+		for (const block of blocks) {
+			const registered = findRegisteredSkillByName(skills, block.name);
+			trackSkill(state, {
+				name: block.name,
+				filePath: registered?.filePath ?? block.location,
+				baseDir: registered?.baseDir ?? dirname(block.location),
+				source: "skill-block",
+			});
+		}
+		persistState();
+		updateSkillReinjectStatusLine(ctx, state, readSettings(ctx));
+	});
+
+	pi.on("tool_call", async (event, ctx) => {
+		if (!isToolCallEventType("read", event)) {
+			return;
+		}
+		trackReadSkillPath(event.input.path, ctx);
 	});
 }
@@ -0,0 +1,93 @@
+import type { SessionEntry } from "@earendil-works/pi-coding-agent";
+import { parseSkillBlocksFromText } from "./detect.js";
+import type { TrackedSkill } from "./state.js";
+
+/** custom_message type for deferred re-inject delivery (SPEC §6.5.1). */
+const SKILL_REINJECT_INJECT_CUSTOM_TYPE = "skill-reinject:inject";
+
+/** Branch slice from firstKeptEntryId through tail (SPEC §6.4). */
+export function getKeptEntries(branch: SessionEntry[], firstKeptEntryId: string): SessionEntry[] {
+	const startIndex = branch.findIndex((entry) => entry.id === firstKeptEntryId);
+	if (startIndex < 0) {
+		return [];
+	}
+	return branch.slice(startIndex);
+}
+
+function extractUserMessageText(content: unknown): string {
+	if (typeof content === "string") {
+		return content;
+	}
+	if (!Array.isArray(content)) {
+		return "";
+	}
+	const parts: string[] = [];
+	for (const part of content) {
+		if (!part || typeof part !== "object") {
+			continue;
+		}
+		const block = part as { type?: string; text?: string };
+		if (block.type === "text" && typeof block.text === "string") {
+			parts.push(block.text);
+		}
+	}
+	return parts.join("\n");
+}
+
+/** Skill names already present as blocks in kept user messages and reinject custom messages (SPEC §6.4). */
+export function skillsPresentInKeptWindow(
+	keptEntries: SessionEntry[],
+	skillNames: readonly string[],
+): Set<string> {
+	const present = new Set<string>();
+	const namesToCheck = new Set(skillNames);
+	if (namesToCheck.size === 0) {
+		return present;
+	}
+
+	for (const entry of keptEntries) {
+		let text = "";
+		if (entry.type === "message" && entry.message.role === "user") {
+			text = extractUserMessageText(entry.message.content);
+		} else if (
+			entry.type === "custom_message" &&
+			entry.customType === SKILL_REINJECT_INJECT_CUSTOM_TYPE &&
+			typeof entry.content === "string"
+		) {
+			text = entry.content;
+		} else {
+			continue;
+		}
+		for (const block of parseSkillBlocksFromText(text)) {
+			if (namesToCheck.has(block.name)) {
+				present.add(block.name);
+			}
+		}
+	}
+	return present;
+}
+
+/** Tracked skills absent from kept window — defer planning stage without registry filter (Phase 14 / B-002). */
+export function filterSkillsNeedingReinjectByKept(
+	tracked: readonly TrackedSkill[],
+	keptPresent: ReadonlySet<string>,
+): string[] {
+	const needing: string[] = [];
+	for (const skill of tracked) {
+		if (!keptPresent.has(skill.name)) {
+			needing.push(skill.name);
+		}
+	}
+	return needing;
+}
+
+/** Tracked skills missing from kept window but still registered (SPEC §5.2, §6.4). */
+export function filterSkillsNeedingReinject(
+	tracked: readonly TrackedSkill[],
+	keptPresent: ReadonlySet<string>,
+	registeredNames: ReadonlySet<string>,
+): string[] {
+	return filterSkillsNeedingReinjectByKept(tracked, keptPresent).filter((name) =>
+		registeredNames.has(name),
+	);
+}
@@ -0,0 +1,438 @@
+import type {
+	BeforeAgentStartEventResult,
+	ExtensionAPI,
+	ExtensionContext,
+	SessionCompactEvent,
+	Skill,
+} from "@earendil-works/pi-coding-agent";
+import { existsSync } from "node:fs";
+import { expandSkill } from "./expand.js";
+import {
+	filterSkillsNeedingReinject,
+	filterSkillsNeedingReinjectByKept,
+	getKeptEntries,
+	skillsPresentInKeptWindow,
+} from "./kept.js";
+import type { SkillReinjectSettings } from "./settings.js";
+import type { CompactionRuntime } from "./compaction.js";
+import type { ExtensionState } from "./state.js";
+
+export const DEFERRED_REINJECT_CUSTOM_TYPE = "skill-reinject:inject";
+
+function notifyWarning(ctx: ExtensionContext | undefined, message: string): void {
+	if (!ctx?.hasUI) {
+		return;
+	}
+	ctx.ui.notify(message, "warning");
+}
+
+function notifyInfo(ctx: ExtensionContext | undefined, message: string): void {
+	if (!ctx?.hasUI) {
+		return;
+	}
+	ctx.ui.notify(message, "info");
+}
+
+function notifySkippedSkill(ctx: ExtensionContext | undefined, skillName: string, reason: string): void {
+	notifyWarning(ctx, `skill-reinject: skipped "${skillName}" — ${reason}`);
+}
+
+/** First registered skill per name; warn on resourceLoader collisions (SPEC §11). */
+export function registeredSkillsByName<T extends Pick<Skill, "name">>(
+	registeredSkills: readonly T[],
+	ctx?: ExtensionContext,
+): Map<string, T> {
+	const byName = new Map<string, T>();
+	const warned = new Set<string>();
+	for (const skill of registeredSkills) {
+		if (byName.has(skill.name)) {
+			if (!warned.has(skill.name)) {
+				warned.add(skill.name);
+				notifyWarning(
+					ctx,
+					`skill-reinject: duplicate skill name "${skill.name}" — using first from resourceLoader`,
+				);
+			}
+			continue;
+		}
+		byName.set(skill.name, skill);
+	}
+	return byName;
+}
+
+/** Names still registered in resourceLoader (SPEC §5.2). */
+export function registeredSkillNames(skills: readonly Pick<Skill, "name">[]): ReadonlySet<string> {
+	return new Set(skills.map((skill) => skill.name));
+}
+
+/** Kept-window skill names present after compaction (shared by plan helpers). */
+function keptPresentAfterCompaction(
+	state: ExtensionState,
+	ctx: ExtensionContext,
+	compactionEvent: SessionCompactEvent,
+): Set<string> {
+	const branch = ctx.sessionManager.getBranch();
+	const keptEntries = getKeptEntries(branch, compactionEvent.compactionEntry.firstKeptEntryId);
+	const trackedNames = state.skills.map((skill) => skill.name);
+	return skillsPresentInKeptWindow(keptEntries, trackedNames);
+}
+
+/**
+ * Defer planning at compaction: tracked skills absent from kept window only (SPEC §6.5.1).
+ * Registry filter runs later on before_agent_start (Phase 14 / B-002).
+ */
+export function planDeferredReinject(
+	state: ExtensionState,
+	ctx: ExtensionContext,
+	compactionEvent: SessionCompactEvent,
+): string[] {
+	const keptPresent = keptPresentAfterCompaction(state, ctx, compactionEvent);
+	return filterSkillsNeedingReinjectByKept(state.skills, keptPresent);
+}
+
+/**
+ * Skill names to re-inject after compaction: tracked, absent from kept window, still registered (SPEC §5.2).
+ * `registeredSkills` comes from resourceLoader — ExtensionContext has no getSkills(); wired in index.ts.
+ */
+export function planReinject(
+	state: ExtensionState,
+	_settings: SkillReinjectSettings,
+	ctx: ExtensionContext,
+	compactionEvent: SessionCompactEvent,
+	registeredSkills: readonly Pick<Skill, "name">[],
+): string[] {
+	const keptPresent = keptPresentAfterCompaction(state, ctx, compactionEvent);
+	return filterSkillsNeedingReinject(
+		state.skills,
+		keptPresent,
+		registeredSkillNames(registeredSkills),
+	);
+}
+
+/** Defer path on session_compact: queue planned skills without sendUserMessage (SPEC §6.5.1, §16.2). */
+export function enqueueDeferredReinjectFromCompact(
+	state: ExtensionState,
+	_settings: SkillReinjectSettings,
+	ctx: ExtensionContext,
+	compactionEvent: SessionCompactEvent,
+	_registeredSkills: readonly Pick<Skill, "name">[],
+): void {
+	state.pendingReinject = planDeferredReinject(state, ctx, compactionEvent);
+}
+
+/**
+ * Update pending queue after session_compact; each compact recalculates or clears (SPEC §16.6).
+ * Manual compaction with default settings keeps stale pending until the next user prompt.
+ */
+export function applyPendingReinjectAfterCompact(
+	state: ExtensionState,
+	compactionRuntime: CompactionRuntime,
+	shouldReinject: boolean,
+	planned: readonly string[],
+): void {
+	if (shouldReinject) {
+		state.pendingReinject = [...planned];
+		return;
+	}
+	if (!compactionRuntime.clearPendingReinjectOnNextUserInput) {
+		state.pendingReinject = [];
+	}
+}
+
+/** Warn when re-injecting many skills; unlimited by default with soft warn above 3 (SPEC §15). */
+export function maybeWarnManySkills(
+	skillCount: number,
+	settings: SkillReinjectSettings,
+	ctx?: ExtensionContext,
+): void {
+	if (skillCount <= 0) {
+		return;
+	}
+	const threshold = settings.maxSkills ?? 3;
+	if (skillCount <= threshold) {
+		return;
+	}
+	if (settings.maxSkills !== undefined) {
+		notifyWarning(
+			ctx,
+			`skill-reinject: re-injecting ${skillCount} skills (maxSkills warn threshold: ${settings.maxSkills})`,
+		);
+		return;
+	}
+	notifyWarning(ctx, `skill-reinject: re-injecting ${skillCount} tracked skills (soft warn above 3)`);
+}
+
+/** Expanded skill-block messages in queue order (SPEC §5.3). */
+export function buildReinjectBlocks(
+	skillNames: readonly string[],
+	state: ExtensionState,
+	settings: SkillReinjectSettings,
+	registeredSkills: readonly Pick<Skill, "name" | "filePath" | "baseDir">[],
+	ctx?: ExtensionContext,
+): string[] {
+	maybeWarnManySkills(skillNames.length, settings, ctx);
+	const registeredByName = registeredSkillsByName(registeredSkills, ctx);
+	const blocks: string[] = [];
+	for (const name of skillNames) {
+		const tracked = state.skills.find((skill) => skill.name === name);
+		if (!tracked) {
+			continue;
+		}
+		const registered = registeredByName.get(name);
+		const filePath = registered?.filePath ?? tracked.filePath;
+		const baseDir = registered?.baseDir ?? tracked.baseDir;
+		if (!registered) {
+			if (settings.requireRegistered) {
+				notifySkippedSkill(ctx, name, "no longer registered");
+				continue;
+			}
+			if (!existsSync(tracked.filePath)) {
+				notifySkippedSkill(ctx, name, "SKILL.md not found on disk");
+				continue;
+			}
+		} else if (!existsSync(filePath)) {
+			notifySkippedSkill(ctx, name, "SKILL.md not found on disk");
+			continue;
+		}
+		try {
+			blocks.push(
+				expandSkill(
+					{
+						name: tracked.name,
+						filePath,
+						baseDir,
+					},
+					settings.suffix,
+				),
+			);
+		} catch {
+			notifySkippedSkill(ctx, name, "SKILL.md not readable");
+		}
+	}
+	return blocks;
+}
+
+/** Combined skill-block user text for pending names in queue order (SPEC §5.3). */
+export function buildDeferredReinjectContent(
+	pendingNames: readonly string[],
+	state: ExtensionState,
+	settings: SkillReinjectSettings,
+	registeredSkills: readonly Pick<Skill, "name" | "filePath" | "baseDir">[],
+	ctx?: ExtensionContext,
+): string {
+	return buildReinjectBlocks(pendingNames, state, settings, registeredSkills, ctx).join("\n\n");
+}
+
+/** Immediate path when agent is idle: first block triggers turn, rest queue as followUp (SPEC §6.5.2). */
+export function sendImmediateReinjectIdle(
+	pi: ExtensionAPI,
+	skillNames: readonly string[],
+	state: ExtensionState,
+	settings: SkillReinjectSettings,
+	registeredSkills: readonly Pick<Skill, "name" | "filePath" | "baseDir">[],
+	ctx?: ExtensionContext,
+): void {
+	const blocks = buildReinjectBlocks(skillNames, state, settings, registeredSkills, ctx);
+	blocks.forEach((block, index) => {
+		pi.sendUserMessage(block, index === 0 ? undefined : { deliverAs: "followUp" });
+	});
+}
+
+/** Immediate path when streaming or overflow willRetry: all blocks as followUp (SPEC §5.2, §6.5.2). */
+export function sendImmediateReinjectAllFollowUp(
+	pi: ExtensionAPI,
+	skillNames: readonly string[],
+	state: ExtensionState,
+	settings: SkillReinjectSettings,
+	registeredSkills: readonly Pick<Skill, "name" | "filePath" | "baseDir">[],
+	ctx?: ExtensionContext,
+): void {
+	for (const block of buildReinjectBlocks(skillNames, state, settings, registeredSkills, ctx)) {
+		pi.sendUserMessage(block, { deliverAs: "followUp" });
+	}
+}
+
+/** Names eligible for re-inject: registered, or on disk when requireRegistered is false (Phase 14 / B-002). */
+export function resolveReinjectSkillNames(
+	state: ExtensionState,
+	settings: SkillReinjectSettings,
+	registeredSkills: readonly Pick<Skill, "name">[],
+	ctx?: ExtensionContext,
+): string[] {
+	const registered = registeredSkillNames(registeredSkills);
+	const names: string[] = [];
+	for (const tracked of state.skills) {
+		if (registered.has(tracked.name)) {
+			names.push(tracked.name);
+			continue;
+		}
+		if (settings.requireRegistered) {
+			continue;
+		}
+		if (existsSync(tracked.filePath)) {
+			notifyInfo(ctx, `skill-reinject: re-injected "${tracked.name}" from disk`);
+			names.push(tracked.name);
+		}
+	}
+	return names;
+}
+
+/** Force re-inject all tracked registered skills for /skill-reinject now (SPEC §7.1). */
+export function reinjectNow(
+	pi: ExtensionAPI,
+	state: ExtensionState,
+	settings: SkillReinjectSettings,
+	ctx: ExtensionContext,
+	registeredSkills: readonly Pick<Skill, "name" | "filePath" | "baseDir">[],
+): void {
+	const skillNames = resolveReinjectSkillNames(state, settings, registeredSkills, ctx);
+	if (skillNames.length === 0) {
+		if (ctx.hasUI) {
+			ctx.ui.notify("skill-reinject: no tracked skills to re-inject", "info");
+		}
+		return;
+	}
+	if (ctx.isIdle()) {
+		sendImmediateReinjectIdle(pi, skillNames, state, settings, registeredSkills, ctx);
+		return;
+	}
+	sendImmediateReinjectAllFollowUp(pi, skillNames, state, settings, registeredSkills, ctx);
+}
+
+/**
+ * Manual `/compact` with default settings: drop stale pending on the next user prompt (SPEC §16.5, §12.3).
+ * Returns true when pending was cleared.
+ */
+export function clearPendingReinjectOnUserPrompt(
+	state: ExtensionState,
+	compactionRuntime: CompactionRuntime,
+): boolean {
+	if (!compactionRuntime.clearPendingReinjectOnNextUserInput) {
+		return false;
+	}
+	compactionRuntime.clearPendingReinjectOnNextUserInput = false;
+	const hadPending = state.pendingReinject.length > 0;
+	state.pendingReinject = [];
+	return hadPending;
+}
+
+/**
+ * Defer consume stage: fresh registry filter on before_agent_start (SPEC §6.5.1, Phase 14 / B-002).
+ * Loose fallback when requireRegistered is false and tracked SKILL.md still exists on disk.
+ */
+export function filterPendingReinjectForConsume(
+	pendingNames: readonly string[],
+	state: ExtensionState,
+	settings: SkillReinjectSettings,
+	registeredSkills: readonly Pick<Skill, "name">[],
+	ctx?: ExtensionContext,
+): string[] {
+	const registered = registeredSkillNames(registeredSkills);
+	const resolved: string[] = [];
+	for (const name of pendingNames) {
+		const tracked = state.skills.find((skill) => skill.name === name);
+		if (!tracked) {
+			continue;
+		}
+		if (registered.has(name)) {
+			resolved.push(name);
+			continue;
+		}
+		if (settings.requireRegistered) {
+			notifySkippedSkill(ctx, name, "no longer registered");
+			continue;
+		}
+		if (existsSync(tracked.filePath)) {
+			notifyInfo(ctx, `skill-reinject: re-injected "${name}" from disk`);
+			resolved.push(name);
+			continue;
+		}
+		notifySkippedSkill(ctx, name, "SKILL.md not found on disk");
+	}
+	return resolved;
+}
+
+/**
+ * Mid-turn defer delivery via sendMessage/steer (SPEC §6.5.1, Phase 15 / B-003).
+ * Clears pendingReinject and records compaction id so before_agent_start does not duplicate.
+ */
+export function deliverDeferredReinjectSteer(
+	pi: ExtensionAPI,
+	state: ExtensionState,
+	settings: SkillReinjectSettings,
+	registeredSkills: readonly Pick<Skill, "name" | "filePath" | "baseDir">[],
+	compactionRuntime: CompactionRuntime,
+	compactionEntryId: string,
+	ctx?: ExtensionContext,
+): boolean {
+	if (state.pendingReinject.length === 0) {
+		return false;
+	}
+	const pendingNames = filterPendingReinjectForConsume(
+		state.pendingReinject,
+		state,
+		settings,
+		registeredSkills,
+		ctx,
+	);
+	const content = buildDeferredReinjectContent(pendingNames, state, settings, registeredSkills, ctx);
+	state.pendingReinject = [];
+	if (!content) {
+		return false;
+	}
+	pi.sendMessage(
+		{
+			customType: DEFERRED_REINJECT_CUSTOM_TYPE,
+			content,
+			display: true,
+		},
+		{ deliverAs: "steer" },
+	);
+	compactionRuntime.deferredDeliveredForCompactionId = compactionEntryId;
+	return true;
+}
+
+/**
+ * Defer path on before_agent_start: inject one combined message, then clear queue (SPEC §6.5.1).
+ * Returns undefined when pendingReinject is empty or manual compaction scheduled a clear (SPEC §16.5).
+ */
+export function tryConsumeDeferredReinject(
+	state: ExtensionState,
+	settings: SkillReinjectSettings,
+	registeredSkills: readonly Pick<Skill, "name" | "filePath" | "baseDir">[],
+	ctx?: ExtensionContext,
+	compactionRuntime?: CompactionRuntime,
+): BeforeAgentStartEventResult | undefined {
+	if (compactionRuntime?.clearPendingReinjectOnNextUserInput) {
+		return undefined;
+	}
+	if (
+		compactionRuntime?.deferredDeliveredForCompactionId &&
+		compactionRuntime.deferredDeliveredForCompactionId === compactionRuntime.lastCompactionEntryId
+	) {
+		return undefined;
+	}
+	if (state.pendingReinject.length === 0) {
+		return undefined;
+	}
+	const pendingNames = filterPendingReinjectForConsume(
+		state.pendingReinject,
+		state,
+		settings,
+		registeredSkills,
+		ctx,
+	);
+	const content = buildDeferredReinjectContent(pendingNames, state, settings, registeredSkills, ctx);
+	if (!content) {
+		state.pendingReinject = [];
+		return undefined;
+	}
+	state.pendingReinject = [];
+	return {
+		message: {
+			customType: DEFERRED_REINJECT_CUSTOM_TYPE,
+			content,
+			display: true,
+		},
+	};
+}
@@ -0,0 +1,99 @@
+import { dirname } from "node:path";
+import type { SessionEntry, Skill } from "@earendil-works/pi-coding-agent";
+import {
+	detectSlashSkill,
+	matchReadPathToSkillWhenEnabled,
+	parseSkillBlocksFromText,
+	userMessageText,
+} from "./detect.js";
+import { findRegisteredSkillByName, resolveRegisteredSkills } from "./skills-registry.js";
+import { trackSkill, type ExtensionState } from "./state.js";
+
+function entrySeenAt(entry: SessionEntry): number {
+	const ts = Date.parse(entry.timestamp);
+	return Number.isFinite(ts) ? ts : Date.now();
+}
+
+function readPathsFromContent(content: unknown): string[] {
+	if (!Array.isArray(content)) {
+		return [];
+	}
+	const paths: string[] = [];
+	for (const part of content) {
+		if (!part || typeof part !== "object") {
+			continue;
+		}
+		const block = part as { type?: string; name?: string; arguments?: Record<string, unknown> };
+		if (block.type !== "toolCall" || block.name !== "read") {
+			continue;
+		}
+		const path = block.arguments?.path;
+		if (typeof path === "string") {
+			paths.push(path);
+		}
+	}
+	return paths;
+}
+
+/** Full branch rescan when no persisted state entry exists (SPEC §6.3). */
+export function rescanSkillsFromBranch(
+	state: ExtensionState,
+	branch: SessionEntry[],
+	cwd: string,
+	registeredSkills: readonly Skill[],
+	trackReadPaths: boolean,
+): void {
+	const skills = resolveRegisteredSkills(cwd, registeredSkills);
+
+	for (const entry of branch) {
+		if (entry.type !== "message") {
+			continue;
+		}
+		const { message } = entry;
+		const seenAt = entrySeenAt(entry);
+
+		if (message.role === "user") {
+			const text = userMessageText(message.content);
+
+			const slashName = detectSlashSkill(text);
+			if (slashName) {
+				const skill = findRegisteredSkillByName(skills, slashName);
+				if (skill) {
+					trackSkill(state, {
+						name: skill.name,
+						filePath: skill.filePath,
+						baseDir: skill.baseDir,
+						source: "slash",
+						seenAt,
+					});
+				}
+			}
+
+			for (const block of parseSkillBlocksFromText(text)) {
+				const registered = findRegisteredSkillByName(skills, block.name);
+				trackSkill(state, {
+					name: block.name,
+					filePath: registered?.filePath ?? block.location,
+					baseDir: registered?.baseDir ?? dirname(block.location),
+					source: "skill-block",
+					seenAt,
+				});
+			}
+		}
+
+		if (message.role === "assistant") {
+			for (const path of readPathsFromContent(message.content)) {
+				const matched = matchReadPathToSkillWhenEnabled(path, skills, trackReadPaths);
+				if (matched) {
+					trackSkill(state, {
+						name: matched.name,
+						filePath: matched.filePath,
+						baseDir: matched.baseDir,
+						source: "read",
+						seenAt,
+					});
+				}
+			}
+		}
+	}
+}
@@ -1,5 +1,5 @@
 import type { ExtensionContext } from "@earendil-works/pi-coding-agent";
-import { SettingsManager, getAgentDir } from "@earendil-works/pi-coding-agent";
+import { getAgentDir } from "@earendil-works/pi-coding-agent";
 import { existsSync, mkdirSync, readFileSync, writeFileSync } from "fs";
 import { dirname, join } from "path";
 import type { AutoCompactIntegration } from "./state";
@@ -24,6 +24,12 @@ export interface SkillReinjectSettings {
 	reinjectOnManualCompaction: boolean;
 	autoCompactIntegration: AutoCompactIntegration;
 	suffix: string;
+	/** Soft warn threshold; omit for unlimited with default warn above 3 (SPEC §15). */
+	maxSkills?: number;
+	/** Verbose reinject filter logging via ui.notify (Phase 14 / B-002). */
+	debug: boolean;
+	/** When true, only re-inject skills present in resourceLoader (Phase 14 / B-002). */
+	requireRegistered: boolean;
 }

 /** Defaults from SPEC §7.3 — extension off until explicitly enabled. */
@@ -34,6 +40,8 @@ export const DEFAULT_SKILL_REINJECT_SETTINGS: Readonly<SkillReinjectSettings> =
 	reinjectOnManualCompaction: false,
 	autoCompactIntegration: "auto",
 	suffix: "[skill-reinject] Re-applied after compaction.",
+	debug: false,
+	requireRegistered: false,
 };

 export function createDefaultSettings(): SkillReinjectSettings {
@@ -72,6 +80,15 @@ export function parseSkillReinjectPartial(raw: unknown): PartialSkillReinjectSet
 	if (typeof obj.suffix === "string") {
 		result.suffix = obj.suffix;
 	}
+	if (typeof obj.maxSkills === "number" && Number.isInteger(obj.maxSkills) && obj.maxSkills > 0) {
+		result.maxSkills = obj.maxSkills;
+	}
+	if (typeof obj.debug === "boolean") {
+		result.debug = obj.debug;
+	}
+	if (typeof obj.requireRegistered === "boolean") {
+		result.requireRegistered = obj.requireRegistered;
+	}
 	return result;
 }

@@ -93,15 +110,14 @@ function extractSkillReinject(settings: object): PartialSkillReinjectSettings {
 	);
 }

-/** Merged global + project settings via Pi SettingsManager (SPEC §7.3). */
+/** Merged global + project settings (SPEC §7.3). Sync file read; avoids SettingsManager / isProjectTrusted() blocking in RPC hooks. */
 export function readSettings(ctx: ExtensionContext): SkillReinjectSettings {
-	const manager = SettingsManager.create(ctx.cwd, getAgentDir(), {
-		projectTrusted: ctx.isProjectTrusted(),
-	});
-	return mergeSkillReinjectSettings(
-		extractSkillReinject(manager.getGlobalSettings()),
-		extractSkillReinject(manager.getProjectSettings()),
-	);
+	const global = extractSkillReinject(readSettingsFile(join(getAgentDir(), "settings.json")));
+	const projectPath = join(ctx.cwd, ".pi/settings.json");
+	const project = existsSync(projectPath)
+		? extractSkillReinject(readSettingsFile(projectPath))
+		: {};
+	return mergeSkillReinjectSettings(global, project);
 }

 function readSettingsFile(settingsPath: string): Record<string, unknown> {
@@ -0,0 +1,27 @@
+import { getAgentDir, loadSkills, type Skill } from "@earendil-works/pi-coding-agent";
+
+/** First match on name collision (SPEC §11). */
+export function findRegisteredSkillByName(
+	skills: readonly Skill[],
+	name: string,
+): Skill | undefined {
+	return skills.find((skill) => skill.name === name);
+}
+
+/** Mirror resourceLoader skill list when cache is empty (e.g. first user input). */
+export function loadRegisteredSkills(cwd: string): Skill[] {
+	return loadSkills({
+		cwd,
+		agentDir: getAgentDir(),
+		skillPaths: [],
+		includeDefaults: true,
+	}).skills;
+}
+
+/** Prefer live skills from before_agent_start; fall back to loadSkills (SPEC §6.2). */
+export function resolveRegisteredSkills(cwd: string, cached: readonly Skill[]): Skill[] {
+	if (cached.length > 0) {
+		return [...cached];
+	}
+	return loadRegisteredSkills(cwd);
+}
@@ -21,6 +21,8 @@ export interface TrackedSkill {
 export interface ExtensionState {
 	version: 1;
 	sessionOverride: boolean | null;
+	/** Session override for autoCompactIntegration (SPEC §7.1, §16.4). */
+	sessionIntegrationOverride: AutoCompactIntegration | null;
 	skills: TrackedSkill[];
 	lastCompactionSource: CompactionSource | null;
 	/** Skill names awaiting re-inject on the next before_agent_start (SPEC §6.5). */
@@ -31,6 +33,8 @@ export interface ExtensionState {
 export interface RuntimeFlags {
 	autoCompactDetected: boolean;
 	autoCompactIntegration: AutoCompactIntegration;
+	/** One-time hint when Pi default compaction coexists with pi-auto-compact (SPEC §16.7). */
+	compactionCoexistenceHintShown: boolean;
 }

 export const STATE_ENTRY_TYPE = "skill-reinject:state";
@@ -47,6 +51,12 @@ function isExtensionState(data: unknown): data is ExtensionState {
 	return (
 		candidate.version === 1 &&
 		(candidate.sessionOverride === null || typeof candidate.sessionOverride === "boolean") &&
+		(candidate.sessionIntegrationOverride === null ||
+			candidate.sessionIntegrationOverride === "auto" ||
+			candidate.sessionIntegrationOverride === "defer" ||
+			candidate.sessionIntegrationOverride === "immediate" ||
+			candidate.sessionIntegrationOverride === "off" ||
+			candidate.sessionIntegrationOverride === undefined) &&
 		Array.isArray(candidate.skills) &&
 		(candidate.lastCompactionSource === null ||
 			candidate.lastCompactionSource === "auto" ||
@@ -74,16 +84,27 @@ export function createInitialState(): ExtensionState {
 	return {
 		version: 1,
 		sessionOverride: null,
+		sessionIntegrationOverride: null,
 		skills: [],
 		lastCompactionSource: null,
 		pendingReinject: [],
 	};
 }

+/** Copy persisted fields into live session state (SPEC §6.3). */
+export function applyExtensionState(target: ExtensionState, loaded: ExtensionState): void {
+	target.sessionOverride = loaded.sessionOverride;
+	target.sessionIntegrationOverride = loaded.sessionIntegrationOverride ?? null;
+	target.skills = loaded.skills;
+	target.lastCompactionSource = loaded.lastCompactionSource;
+	target.pendingReinject = loaded.pendingReinject;
+}
+
 export function createRuntimeFlags(): RuntimeFlags {
 	return {
 		autoCompactDetected: false,
 		autoCompactIntegration: "auto",
+		compactionCoexistenceHintShown: false,
 	};
 }

@@ -0,0 +1,108 @@
+import { describe, expect, it } from "vitest";
+import {
+	detectAndCachePiAutoCompact,
+	detectPiAutoCompact,
+	maybeNotifyCompactionCoexistenceHint,
+	PI_AUTO_COMPACT_FOLLOW_UP_PREFIXES,
+	resolveDeliveryMode,
+	resolvePiDefaultCompactionEnabled,
+} from "../src/auto-compact";
+import { createDefaultSettings } from "../src/settings";
+import { createRuntimeFlags } from "../src/state";
+
+describe("detectPiAutoCompact", () => {
+	it("returns true when auto-compact command is registered", () => {
+		const pi = {
+			getCommands: () => [{ name: "auto-compact" }],
+		};
+		expect(detectPiAutoCompact(pi as never)).toBe(true);
+	});
+
+	it("returns false when auto-compact command is absent", () => {
+		const pi = {
+			getCommands: () => [{ name: "skill-reinject" }],
+		};
+		expect(detectPiAutoCompact(pi as never)).toBe(false);
+	});
+});
+
+describe("detectAndCachePiAutoCompact", () => {
+	it("writes detect result into runtime flags", () => {
+		const runtime = createRuntimeFlags();
+		const pi = {
+			getCommands: () => [{ name: "auto-compact" }],
+		};
+		expect(detectAndCachePiAutoCompact(pi as never, runtime)).toBe(true);
+		expect(runtime.autoCompactDetected).toBe(true);
+	});
+});
+
+describe("resolveDeliveryMode", () => {
+	it("defers when pi-auto-compact is cached as detected", () => {
+		const runtime = createRuntimeFlags();
+		runtime.autoCompactDetected = true;
+		expect(resolveDeliveryMode(createDefaultSettings(), runtime)).toBe("defer");
+	});
+});
+
+describe("PI_AUTO_COMPACT_FOLLOW_UP_PREFIXES", () => {
+	it("documents pi-auto-compact follow-up phrases from SPEC §16.9", () => {
+		expect([...PI_AUTO_COMPACT_FOLLOW_UP_PREFIXES]).toEqual([
+			"Auto-compact ran before this turn.",
+			"Auto-compact ran mid-turn.",
+			"Emergency auto-compact ran.",
+			"Auto-compact ran on session resume.",
+		]);
+	});
+});
+
+describe("resolvePiDefaultCompactionEnabled", () => {
+	it("defaults to enabled when compaction settings are absent", () => {
+		expect(resolvePiDefaultCompactionEnabled({}, {})).toBe(true);
+	});
+
+	it("lets project override global compaction.enabled", () => {
+		expect(
+			resolvePiDefaultCompactionEnabled(
+				{ compaction: { enabled: true } },
+				{ compaction: { enabled: false } },
+			),
+		).toBe(false);
+	});
+});
+
+describe("maybeNotifyCompactionCoexistenceHint", () => {
+	it("notifies once when pi-auto-compact and Pi compaction are both active", () => {
+		const runtime = createRuntimeFlags();
+		runtime.autoCompactDetected = true;
+		const notifications: string[] = [];
+		const ctx = {
+			hasUI: true,
+			ui: {
+				notify: (message: string) => {
+					notifications.push(message);
+				},
+			},
+		};
+
+		maybeNotifyCompactionCoexistenceHint(ctx as never, runtime, true);
+		maybeNotifyCompactionCoexistenceHint(ctx as never, runtime, true);
+
+		expect(notifications).toHaveLength(1);
+		expect(runtime.compactionCoexistenceHintShown).toBe(true);
+	});
+
+	it("skips notify when pi-auto-compact is not detected", () => {
+		const runtime = createRuntimeFlags();
+		const notifications: string[] = [];
+		const ctx = {
+			hasUI: true,
+			ui: { notify: (message: string) => notifications.push(message) },
+		};
+
+		maybeNotifyCompactionCoexistenceHint(ctx as never, runtime, true);
+
+		expect(notifications).toHaveLength(0);
+		expect(runtime.compactionCoexistenceHintShown).toBe(false);
+	});
+});
@@ -0,0 +1,98 @@
+import { describe, expect, it } from "vitest";
+import { planDeferredReinject, planReinject } from "../src/reinject.js";
+import { createDefaultSettings } from "../src/settings.js";
+import { createInitialState, trackSkill } from "../src/state.js";
+
+describe("B-002 pre-fix filter hypothesis", () => {
+	it("planned empty when skill stays in kept window even if registered", () => {
+		const state = createInitialState();
+		trackSkill(state, {
+			name: "fup-blame-commits",
+			filePath: "/home/user/.cursor/skills/fup-blame-commits/SKILL.md",
+			baseDir: "/home/user/.cursor/skills/fup-blame-commits",
+			source: "slash",
+		});
+
+		const branch = [
+			{
+				id: "keep-1",
+				type: "message",
+				message: {
+					role: "user",
+					content:
+						'<skill name="fup-blame-commits" location="/path/SKILL.md">\nbody\n</skill>',
+				},
+			},
+		] as never;
+
+		const planned = planReinject(
+			state,
+			createDefaultSettings(),
+			{
+				sessionManager: { getBranch: () => branch },
+			} as never,
+			{ compactionEntry: { firstKeptEntryId: "keep-1" } } as never,
+			[{ name: "fup-blame-commits" }],
+		);
+
+		expect(planned).toEqual([]);
+	});
+
+	it("pre-fix: registered empty drops skill even when absent from kept (post-fix should reinject)", () => {
+		const state = createInitialState();
+		trackSkill(state, {
+			name: "fup-blame-commits",
+			filePath: "/home/user/.cursor/skills/fup-blame-commits/SKILL.md",
+			baseDir: "/home/user/.cursor/skills/fup-blame-commits",
+			source: "skill-block",
+		});
+
+		const branch = [
+			{
+				id: "keep-1",
+				type: "message",
+				message: { role: "user", content: "plain text after compact" },
+			},
+		] as never;
+
+		const planned = planReinject(
+			state,
+			createDefaultSettings(),
+			{
+				sessionManager: { getBranch: () => branch },
+			} as never,
+			{ compactionEntry: { firstKeptEntryId: "keep-1" } } as never,
+			[],
+		);
+
+		expect(planned).toEqual([]);
+	});
+
+	it("defer plan includes skill absent from kept even when registered is empty", () => {
+		const state = createInitialState();
+		trackSkill(state, {
+			name: "fup-blame-commits",
+			filePath: "/home/user/.cursor/skills/fup-blame-commits/SKILL.md",
+			baseDir: "/home/user/.cursor/skills/fup-blame-commits",
+			source: "skill-block",
+		});
+
+		const branch = [
+			{
+				id: "keep-1",
+				type: "message",
+				message: { role: "user", content: "plain text after compact" },
+			},
+		] as never;
+
+		const planned = planDeferredReinject(
+			state,
+			{
+				sessionManager: { getBranch: () => branch },
+			} as never,
+			{ compactionEntry: { firstKeptEntryId: "keep-1" } } as never,
+		);
+
+		expect(planned).toEqual(["fup-blame-commits"]);
+	});
+});
@@ -0,0 +1,83 @@
+import { describe, expect, it, vi } from "vitest";
+import { handleSkillReinjectCommand } from "../src/commands";
+import { createInitialState, createRuntimeFlags } from "../src/state";
+
+function createNoUiCommandContext() {
+	const notify = vi.fn();
+	return {
+		hasUI: false,
+		mode: "rpc" as const,
+		ui: { notify, setStatus: vi.fn() },
+		cwd: process.cwd(),
+		isProjectTrusted: () => true,
+		isIdle: () => true,
+	};
+}
+
+function createDeps() {
+	const state = createInitialState();
+	const persistState = vi.fn();
+	const pi = {
+		sendUserMessage: vi.fn(),
+		registerCommand: vi.fn(),
+		appendEntry: vi.fn(),
+	};
+	return {
+		state,
+		persistState,
+		pi,
+		runtime: createRuntimeFlags(),
+		getRegisteredSkills: () => [],
+	};
+}
+
+describe("handleSkillReinjectCommand without UI", () => {
+	it("does not throw on status", async () => {
+		const ctx = createNoUiCommandContext();
+		const deps = createDeps();
+
+		await expect(handleSkillReinjectCommand("", ctx as never, deps as never)).resolves.toBeUndefined();
+		expect(ctx.ui.notify).not.toHaveBeenCalled();
+	});
+
+	it("persists session toggle without notify", async () => {
+		const ctx = createNoUiCommandContext();
+		const deps = createDeps();
+
+		await handleSkillReinjectCommand("on", ctx as never, deps as never);
+
+		expect(deps.state.sessionOverride).toBe(true);
+		expect(deps.persistState).toHaveBeenCalledTimes(1);
+		expect(ctx.ui.notify).not.toHaveBeenCalled();
+	});
+
+	it("clears tracked skills without notify", async () => {
+		const ctx = createNoUiCommandContext();
+		const deps = createDeps();
+		deps.state.skills.push({
+			name: "alpha",
+			filePath: "/a/SKILL.md",
+			baseDir: "/a",
+			firstSeenAt: 1,
+			lastSeenAt: 1,
+			sources: ["slash"],
+		});
+
+		await handleSkillReinjectCommand("clear", ctx as never, deps as never);
+
+		expect(deps.state.skills).toEqual([]);
+		expect(deps.persistState).toHaveBeenCalledTimes(1);
+		expect(ctx.ui.notify).not.toHaveBeenCalled();
+	});
+
+	it("persists integration override without notify", async () => {
+		const ctx = createNoUiCommandContext();
+		const deps = createDeps();
+
+		await handleSkillReinjectCommand("integration defer", ctx as never, deps as never);
+
+		expect(deps.state.sessionIntegrationOverride).toBe("defer");
+		expect(deps.persistState).toHaveBeenCalledTimes(1);
+		expect(ctx.ui.notify).not.toHaveBeenCalled();
+	});
+});
@@ -0,0 +1,47 @@
+import { describe, expect, it } from "vitest";
+import {
+	consumeCompactionOnSessionCompact,
+	createCompactionRuntime,
+	ensureCompactionSourceMarked,
+	markManualCompactionFromInput,
+} from "../src/compaction";
+import { createDefaultSettings } from "../src/settings";
+import { createInitialState } from "../src/state";
+
+describe("compaction source fallback on session_compact", () => {
+	it("infers auto when session_compact runs without prior session_before_compact", () => {
+		const runtime = createCompactionRuntime();
+		const state = createInitialState();
+		expect(runtime.pendingCompactionSource).toBeNull();
+
+		ensureCompactionSourceMarked(runtime);
+		const shouldReinject = consumeCompactionOnSessionCompact(
+			runtime,
+			state,
+			true,
+			createDefaultSettings(),
+		);
+
+		expect(shouldReinject).toBe(true);
+		expect(state.lastCompactionSource).toBe("auto");
+		expect(runtime.pendingCompactionSource).toBeNull();
+	});
+
+	it("keeps manual source from input and skips reinject by default", () => {
+		const runtime = createCompactionRuntime();
+		const state = createInitialState();
+		markManualCompactionFromInput("/compact", runtime);
+
+		ensureCompactionSourceMarked(runtime);
+		const shouldReinject = consumeCompactionOnSessionCompact(
+			runtime,
+			state,
+			true,
+			createDefaultSettings(),
+		);
+
+		expect(shouldReinject).toBe(false);
+		expect(state.lastCompactionSource).toBe("manual");
+		expect(runtime.clearPendingReinjectOnNextUserInput).toBe(true);
+	});
+});
@@ -0,0 +1,85 @@
+import { describe, expect, it } from "vitest";
+import {
+	detectSlashSkill,
+	matchReadPathToSkill,
+	matchReadPathToSkillWhenEnabled,
+	parseSkillBlocksFromText,
+	type SkillPathMeta,
+} from "../src/detect";
+
+const sampleSkills: SkillPathMeta[] = [
+	{
+		name: "brave-search",
+		filePath: "/home/user/.pi/skills/brave-search/SKILL.md",
+		baseDir: "/home/user/.pi/skills/brave-search",
+	},
+	{
+		name: "pdf-tools",
+		filePath: "/proj/.pi/skills/pdf-tools/SKILL.md",
+		baseDir: "/proj/.pi/skills/pdf-tools",
+	},
+];
+
+describe("detectSlashSkill", () => {
+	it("detects slash command at start of text", () => {
+		expect(detectSlashSkill("/skill:brave-search")).toBe("brave-search");
+		expect(detectSlashSkill("/skill:pdf-tools extract pages")).toBe("pdf-tools");
+	});
+
+	it("returns null for non-slash or invalid names", () => {
+		expect(detectSlashSkill("hello")).toBeNull();
+		expect(detectSlashSkill(" /skill:foo")).toBeNull();
+		expect(detectSlashSkill("/skill:Bad_Name")).toBeNull();
+	});
+});
+
+describe("parseSkillBlocksFromText", () => {
+	const block =
+		'<skill name="brave-search" location="/home/user/.pi/skills/brave-search/SKILL.md">\nbody\n</skill>';
+
+	it("parses one or more skill blocks", () => {
+		expect(parseSkillBlocksFromText(block)).toEqual([
+			{
+				name: "brave-search",
+				location: "/home/user/.pi/skills/brave-search/SKILL.md",
+				content: "body",
+			},
+		]);
+		expect(parseSkillBlocksFromText(`${block}\n\n${block.replace("brave-search", "pdf-tools")}`)).toHaveLength(2);
+	});
+
+	it("returns empty array when no blocks", () => {
+		expect(parseSkillBlocksFromText("plain text")).toEqual([]);
+		expect(parseSkillBlocksFromText('<skill name="x"')).toEqual([]);
+	});
+});
+
+describe("matchReadPathToSkill", () => {
+	it("matches absolute skill filePath", () => {
+		expect(matchReadPathToSkill("/home/user/.pi/skills/brave-search/SKILL.md", sampleSkills)?.name).toBe(
+			"brave-search",
+		);
+	});
+
+	it("matches relative path via skill baseDir", () => {
+		expect(matchReadPathToSkill("SKILL.md", [sampleSkills[0]])?.name).toBe("brave-search");
+	});
+
+	it("returns null for unrelated paths", () => {
+		expect(matchReadPathToSkill("/tmp/README.md", sampleSkills)).toBeNull();
+	});
+});
+
+describe("matchReadPathToSkillWhenEnabled", () => {
+	it("skips read detection when trackReadPaths is false", () => {
+		expect(
+			matchReadPathToSkillWhenEnabled("/home/user/.pi/skills/brave-search/SKILL.md", sampleSkills, false),
+		).toBeNull();
+	});
+
+	it("delegates to matchReadPathToSkill when enabled", () => {
+		expect(
+			matchReadPathToSkillWhenEnabled("/home/user/.pi/skills/brave-search/SKILL.md", sampleSkills, true)?.name,
+		).toBe("brave-search");
+	});
+});
@@ -0,0 +1,96 @@
+import { describe, expect, it, vi } from "vitest";
+import { buildReinjectDiagSnapshot, notifyReinjectDiag } from "../src/diag.js";
+import { createDefaultSettings } from "../src/settings.js";
+import { createInitialState } from "../src/state.js";
+
+describe("buildReinjectDiagSnapshot", () => {
+	it("collects tracked, kept, registered, planned, and pending", () => {
+		const state = createInitialState();
+		state.skills.push({
+			name: "alpha",
+			filePath: "/skills/alpha/SKILL.md",
+			baseDir: "/skills/alpha",
+			firstSeenAt: 1,
+			lastSeenAt: 1,
+			sources: ["slash"],
+		});
+		state.pendingReinject = ["alpha"];
+
+		expect(
+			buildReinjectDiagSnapshot(
+				state,
+				[{ name: "beta" }],
+				new Set(["gamma"]),
+				["alpha"],
+				{
+					compactionSource: "auto",
+					sourceInferred: true,
+					deliveryBranch: "steer",
+					isIdle: false,
+				},
+			),
+		).toEqual({
+			tracked: ["alpha"],
+			kept: ["gamma"],
+			registered: ["beta"],
+			planned: ["alpha"],
+			pending: ["alpha"],
+			compactionSource: "auto",
+			sourceInferred: true,
+			deliveryBranch: "steer",
+			isIdle: false,
+		});
+	});
+});
+
+describe("notifyReinjectDiag", () => {
+	it("no-ops when debug is off", () => {
+		const notify = vi.fn();
+		notifyReinjectDiag(
+			{
+				hasUI: true,
+				ui: { notify },
+			} as never,
+			createDefaultSettings(),
+			"session_compact",
+			{
+				tracked: [],
+				kept: [],
+				registered: [],
+				planned: [],
+				pending: [],
+			},
+		);
+		expect(notify).not.toHaveBeenCalled();
+	});
+
+	it("notifies with JSON snapshot when debug is on", () => {
+		const notify = vi.fn();
+		const stderrSpy = vi.spyOn(console, "error").mockImplementation(() => {});
+		const settings = { ...createDefaultSettings(), debug: true };
+		const snapshot = {
+			tracked: ["a"],
+			kept: [],
+			registered: [],
+			planned: ["a"],
+			pending: ["a"],
+		};
+		notifyReinjectDiag(
+			{
+				hasUI: true,
+				ui: { notify },
+			} as never,
+			settings,
+			"before_agent_start",
+			snapshot,
+		);
+		expect(stderrSpy).toHaveBeenCalledWith(
+			`skill-reinject [before_agent_start]: ${JSON.stringify(snapshot)}`,
+		);
+		expect(notify).toHaveBeenCalledWith(
+			`skill-reinject [before_agent_start]: ${JSON.stringify(snapshot)}`,
+			"info",
+		);
+		stderrSpy.mockRestore();
+	});
+});
@@ -0,0 +1,117 @@
+import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from "fs";
+import { tmpdir } from "os";
+import { join } from "path";
+import { afterEach, describe, expect, it } from "vitest";
+import {
+	appendSuffix,
+	expandSkill,
+	formatBlock,
+	readSkillBody,
+	type SkillBlockMeta,
+} from "../src/expand";
+
+const tempDirs: string[] = [];
+
+afterEach(() => {
+	for (const dir of tempDirs.splice(0)) {
+		rmSync(dir, { recursive: true, force: true });
+	}
+});
+
+function writeSkillMd(dir: string, name: string, content: string): SkillBlockMeta {
+	const baseDir = join(dir, name);
+	const filePath = join(baseDir, "SKILL.md");
+	mkdirSync(baseDir, { recursive: true });
+	writeFileSync(filePath, content, "utf-8");
+	return { name, filePath, baseDir };
+}
+
+describe("readSkillBody", () => {
+	it("strips YAML frontmatter and trims body", () => {
+		const dir = mkdtempSync(join(tmpdir(), "pi-skill-reinject-expand-"));
+		tempDirs.push(dir);
+		const meta = writeSkillMd(
+			dir,
+			"demo-skill",
+			`---
+name: demo-skill
+description: Demo
+---
+
+# Instructions
+
+Do the thing.
+`,
+		);
+
+		expect(readSkillBody(meta.filePath)).toBe("# Instructions\n\nDo the thing.");
+	});
+
+	it("returns trimmed body when frontmatter is absent", () => {
+		const dir = mkdtempSync(join(tmpdir(), "pi-skill-reinject-expand-"));
+		tempDirs.push(dir);
+		const meta = writeSkillMd(dir, "plain", "  hello world  \n");
+
+		expect(readSkillBody(meta.filePath)).toBe("hello world");
+	});
+});
+
+describe("formatBlock", () => {
+	it("embeds name, location, baseDir, and body", () => {
+		const meta: SkillBlockMeta = {
+			name: "brave-search",
+			filePath: "/home/user/.pi/skills/brave-search/SKILL.md",
+			baseDir: "/home/user/.pi/skills/brave-search",
+		};
+
+		expect(formatBlock(meta, "Search the web.")).toBe(
+			`<skill name="brave-search" location="/home/user/.pi/skills/brave-search/SKILL.md">
+References are relative to /home/user/.pi/skills/brave-search.
+
+Search the web.
+</skill>`,
+		);
+	});
+});
+
+describe("appendSuffix", () => {
+	it("appends suffix after a blank line", () => {
+		const block = "<skill>body</skill>";
+		expect(appendSuffix(block, "[skill-reinject] note")).toBe(
+			`${block}\n\n[skill-reinject] note`,
+		);
+	});
+
+	it("returns block unchanged for empty or whitespace suffix", () => {
+		const block = "<skill>body</skill>";
+		expect(appendSuffix(block, undefined)).toBe(block);
+		expect(appendSuffix(block, "   ")).toBe(block);
+	});
+});
+
+describe("expandSkill", () => {
+	it("produces full injectable text with optional suffix", () => {
+		const dir = mkdtempSync(join(tmpdir(), "pi-skill-reinject-expand-"));
+		tempDirs.push(dir);
+		const meta = writeSkillMd(
+			dir,
+			"pdf-tools",
+			`---
+name: pdf-tools
+---
+
+Extract pages from PDFs.
+`,
+		);
+
+		const withoutSuffix = expandSkill(meta);
+		expect(withoutSuffix).toContain('name="pdf-tools"');
+		expect(withoutSuffix).toContain(`location="${meta.filePath}"`);
+		expect(withoutSuffix).toContain(`References are relative to ${meta.baseDir}.`);
+		expect(withoutSuffix).toContain("Extract pages from PDFs.");
+
+		expect(expandSkill(meta, "[skill-reinject] Re-applied.")).toBe(
+			`${withoutSuffix}\n\n[skill-reinject] Re-applied.`,
+		);
+	});
+});
@@ -0,0 +1,173 @@
+import type { SessionEntry } from "@earendil-works/pi-coding-agent";
+import { describe, expect, it } from "vitest";
+import {
+	filterSkillsNeedingReinject,
+	filterSkillsNeedingReinjectByKept,
+	getKeptEntries,
+	skillsPresentInKeptWindow,
+} from "../src/kept";
+import type { TrackedSkill } from "../src/state";
+
+const ts = "2024-12-03T14:00:00.000Z";
+
+function userMessage(id: string, content: string): SessionEntry {
+	return {
+		type: "message",
+		id,
+		parentId: null,
+		timestamp: ts,
+		message: { role: "user", content },
+	} as SessionEntry;
+}
+
+function assistantMessage(id: string, content: string): SessionEntry {
+	return {
+		type: "message",
+		id,
+		parentId: null,
+		timestamp: ts,
+		message: { role: "assistant", content: [{ type: "text", text: content }] },
+	} as SessionEntry;
+}
+
+function compactionEntry(id: string, firstKeptEntryId: string): SessionEntry {
+	return {
+		type: "compaction",
+		id,
+		parentId: null,
+		timestamp: ts,
+		summary: "summary",
+		firstKeptEntryId,
+		tokensBefore: 1000,
+	} as SessionEntry;
+}
+
+function reinjectCustomMessage(id: string, content: string): SessionEntry {
+	return {
+		type: "custom_message",
+		id,
+		parentId: null,
+		timestamp: ts,
+		customType: "skill-reinject:inject",
+		content,
+		display: true,
+	} as SessionEntry;
+}
+
+const skillBlock = (name: string) =>
+	`<skill name="${name}" location="/skills/${name}/SKILL.md">\nbody\n</skill>`;
+
+const trackedSkills: TrackedSkill[] = [
+	{
+		name: "alpha",
+		filePath: "/skills/alpha/SKILL.md",
+		baseDir: "/skills/alpha",
+		firstSeenAt: 1,
+		lastSeenAt: 1,
+		sources: ["slash"],
+	},
+	{
+		name: "beta",
+		filePath: "/skills/beta/SKILL.md",
+		baseDir: "/skills/beta",
+		firstSeenAt: 2,
+		lastSeenAt: 2,
+		sources: ["skill-block"],
+	},
+];
+
+describe("getKeptEntries", () => {
+	const branch: SessionEntry[] = [
+		userMessage("e1", "old"),
+		userMessage("e2", "kept start"),
+		assistantMessage("e3", "reply"),
+		compactionEntry("e4", "e2"),
+		userMessage("e5", "after compact"),
+	];
+
+	it("slices from firstKeptEntryId through tail", () => {
+		expect(getKeptEntries(branch, "e2").map((entry) => entry.id)).toEqual(["e2", "e3", "e4", "e5"]);
+	});
+
+	it("returns empty when firstKeptEntryId is missing", () => {
+		expect(getKeptEntries(branch, "missing")).toEqual([]);
+		expect(getKeptEntries([], "e1")).toEqual([]);
+	});
+});
+
+describe("skillsPresentInKeptWindow", () => {
+	it("detects skill blocks in kept user messages", () => {
+		const kept = [userMessage("k1", skillBlock("alpha")), assistantMessage("k2", "ignored")];
+		expect(skillsPresentInKeptWindow(kept, ["alpha", "beta"])).toEqual(new Set(["alpha"]));
+	});
+
+	it("returns empty when no tracked skills or no blocks", () => {
+		expect(skillsPresentInKeptWindow([userMessage("k1", "plain")], ["alpha"])).toEqual(new Set());
+		expect(skillsPresentInKeptWindow([userMessage("k1", skillBlock("alpha"))], [])).toEqual(new Set());
+		expect(skillsPresentInKeptWindow([], ["alpha", "beta"])).toEqual(new Set());
+	});
+
+	it("detects skill blocks in skill-reinject:inject custom messages", () => {
+		const kept = [reinjectCustomMessage("inj1", skillBlock("beta"))];
+		expect(skillsPresentInKeptWindow(kept, ["alpha", "beta"])).toEqual(new Set(["beta"]));
+	});
+
+	it("ignores reinject custom outside kept slice when slicing branch", () => {
+		const branch: SessionEntry[] = [
+			reinjectCustomMessage("inj0", skillBlock("alpha")),
+			userMessage("e2", "kept start"),
+			compactionEntry("e4", "e2"),
+		];
+		const kept = getKeptEntries(branch, "e2");
+		expect(skillsPresentInKeptWindow(kept, ["alpha", "beta"])).toEqual(new Set());
+		expect(skillsPresentInKeptWindow(kept, ["alpha"])).toEqual(new Set());
+	});
+
+	it("counts reinject custom inside kept slice", () => {
+		const branch: SessionEntry[] = [
+			userMessage("e2", "kept start"),
+			reinjectCustomMessage("inj1", skillBlock("alpha")),
+			compactionEntry("e4", "e2"),
+		];
+		const kept = getKeptEntries(branch, "e2");
+		expect(skillsPresentInKeptWindow(kept, ["alpha", "beta"])).toEqual(new Set(["alpha"]));
+	});
+});
+
+describe("filterSkillsNeedingReinjectByKept", () => {
+	it("returns tracked skills absent from kept window regardless of registration", () => {
+		const keptPresent = new Set(["alpha"]);
+		expect(filterSkillsNeedingReinjectByKept(trackedSkills, keptPresent)).toEqual(["beta"]);
+	});
+
+	it("preserves tracked order including unregistered names", () => {
+		const keptPresent = new Set<string>();
+		expect(filterSkillsNeedingReinjectByKept(trackedSkills, keptPresent)).toEqual(["alpha", "beta"]);
+	});
+
+	it("returns empty when all tracked skills are in kept window", () => {
+		const keptPresent = new Set(["alpha", "beta"]);
+		expect(filterSkillsNeedingReinjectByKept(trackedSkills, keptPresent)).toEqual([]);
+	});
+});
+
+describe("filterSkillsNeedingReinject", () => {
+	it("returns registered tracked skills absent from kept window", () => {
+		const keptPresent = new Set(["alpha"]);
+		const registered = new Set(["alpha", "beta"]);
+		expect(filterSkillsNeedingReinject(trackedSkills, keptPresent, registered)).toEqual(["beta"]);
+	});
+
+	it("excludes unregistered skills and preserves tracked order", () => {
+		const keptPresent = new Set<string>();
+		const registered = new Set(["alpha", "beta"]);
+		expect(filterSkillsNeedingReinject(trackedSkills, keptPresent, registered)).toEqual(["alpha", "beta"]);
+		expect(filterSkillsNeedingReinject(trackedSkills, keptPresent, new Set(["beta"]))).toEqual(["beta"]);
+	});
+
+	it("returns empty when all tracked skills are in kept window", () => {
+		const keptPresent = new Set(["alpha", "beta"]);
+		const registered = new Set(["alpha", "beta"]);
+		expect(filterSkillsNeedingReinject(trackedSkills, keptPresent, registered)).toEqual([]);
+	});
+});
@@ -0,0 +1,31 @@
+import { describe, expect, it, vi } from "vitest";
+import { registeredSkillsByName } from "../src/reinject";
+
+describe("registeredSkillsByName", () => {
+	it("keeps the first skill when names collide", () => {
+		const first = { name: "alpha", filePath: "/a/SKILL.md", baseDir: "/a" };
+		const second = { name: "alpha", filePath: "/b/SKILL.md", baseDir: "/b" };
+
+		const byName = registeredSkillsByName([first, second]);
+
+		expect(byName.get("alpha")).toBe(first);
+	});
+
+	it("warns once per duplicate name", () => {
+		const notify = vi.fn();
+		const ctx = { hasUI: true, ui: { notify } } as never;
+		const skills = [
+			{ name: "alpha", filePath: "/a/SKILL.md", baseDir: "/a" },
+			{ name: "alpha", filePath: "/b/SKILL.md", baseDir: "/b" },
+			{ name: "alpha", filePath: "/c/SKILL.md", baseDir: "/c" },
+		];
+
+		registeredSkillsByName(skills, ctx);
+
+		expect(notify).toHaveBeenCalledTimes(1);
+		expect(notify).toHaveBeenCalledWith(
+			'skill-reinject: duplicate skill name "alpha" — using first from resourceLoader',
+			"warning",
+		);
+	});
+});
@@ -0,0 +1,111 @@
+import { existsSync, mkdtempSync, mkdirSync, rmSync, writeFileSync } from "fs";
+import { tmpdir } from "os";
+import { join } from "path";
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { filterPendingReinjectForConsume, tryConsumeDeferredReinject } from "../src/reinject";
+import { createDefaultSettings } from "../src/settings";
+import { createInitialState, trackSkill } from "../src/state";
+
+const tempDirs: string[] = [];
+
+afterEach(() => {
+	for (const dir of tempDirs.splice(0)) {
+		rmSync(dir, { recursive: true, force: true });
+	}
+});
+
+function tempSkillDir(name: string): { filePath: string; baseDir: string } {
+	const root = mkdtempSync(join(tmpdir(), "pi-skill-reinject-consume-"));
+	tempDirs.push(root);
+	const baseDir = join(root, name);
+	mkdirSync(baseDir, { recursive: true });
+	const filePath = join(baseDir, "SKILL.md");
+	writeFileSync(filePath, "# skill\n", "utf8");
+	return { filePath, baseDir };
+}
+
+describe("filterPendingReinjectForConsume", () => {
+	it("keeps registered pending skills", () => {
+		const state = createInitialState();
+		trackSkill(state, {
+			name: "alpha",
+			filePath: "/skills/alpha/SKILL.md",
+			baseDir: "/skills/alpha",
+			source: "slash",
+		});
+
+		expect(
+			filterPendingReinjectForConsume(
+				["alpha"],
+				state,
+				createDefaultSettings(),
+				[{ name: "alpha" }],
+			),
+		).toEqual(["alpha"]);
+	});
+
+	it("includes unregistered skill from disk when requireRegistered is false", () => {
+		const { filePath, baseDir } = tempSkillDir("loose");
+		const state = createInitialState();
+		trackSkill(state, { name: "loose", filePath, baseDir, source: "slash" });
+		const notify = vi.fn();
+		const ctx = { hasUI: true, ui: { notify } } as never;
+
+		expect(
+			filterPendingReinjectForConsume(["loose"], state, createDefaultSettings(), [], ctx),
+		).toEqual(["loose"]);
+		expect(notify).toHaveBeenCalledWith('skill-reinject: re-injected "loose" from disk', "info");
+	});
+
+	it("skips unregistered skill when requireRegistered is true", () => {
+		const { filePath, baseDir } = tempSkillDir("strict");
+		const state = createInitialState();
+		trackSkill(state, { name: "strict", filePath, baseDir, source: "slash" });
+		const notify = vi.fn();
+		const ctx = { hasUI: true, ui: { notify } } as never;
+		const settings = createDefaultSettings();
+		settings.requireRegistered = true;
+
+		expect(filterPendingReinjectForConsume(["strict"], state, settings, [], ctx)).toEqual([]);
+		expect(notify).toHaveBeenCalledWith(
+			'skill-reinject: skipped "strict" — no longer registered',
+			"warning",
+		);
+	});
+
+	it("skips when tracked file is missing on disk", () => {
+		const state = createInitialState();
+		trackSkill(state, {
+			name: "missing",
+			filePath: "/no/such/SKILL.md",
+			baseDir: "/no/such",
+			source: "slash",
+		});
+		expect(existsSync("/no/such/SKILL.md")).toBe(false);
+		const notify = vi.fn();
+		const ctx = { hasUI: true, ui: { notify } } as never;
+
+		expect(
+			filterPendingReinjectForConsume(["missing"], state, createDefaultSettings(), [], ctx),
+		).toEqual([]);
+		expect(notify).toHaveBeenCalledWith(
+			'skill-reinject: skipped "missing" — SKILL.md not found on disk',
+			"warning",
+		);
+	});
+});
+
+describe("tryConsumeDeferredReinject loose path", () => {
+	it("injects skill block from tracked filePath when not registered", () => {
+		const { filePath, baseDir } = tempSkillDir("loose");
+		const state = createInitialState();
+		trackSkill(state, { name: "loose", filePath, baseDir, source: "slash" });
+		state.pendingReinject = ["loose"];
+
+		const result = tryConsumeDeferredReinject(state, createDefaultSettings(), [], undefined);
+
+		expect(result?.message?.content).toContain('<skill name="loose"');
+		expect(result?.message?.content).toContain("[skill-reinject] Re-applied after compaction.");
+		expect(state.pendingReinject).toEqual([]);
+	});
+});
@@ -0,0 +1,37 @@
+import { describe, expect, it } from "vitest";
+import { createCompactionRuntime } from "../src/compaction";
+import { applyPendingReinjectAfterCompact } from "../src/reinject";
+import { createInitialState } from "../src/state";
+
+describe("applyPendingReinjectAfterCompact", () => {
+	it("replaces pending with a new plan on each compact", () => {
+		const runtime = createCompactionRuntime();
+		const state = createInitialState();
+		state.pendingReinject = ["alpha"];
+
+		applyPendingReinjectAfterCompact(state, runtime, true, ["beta", "gamma"]);
+
+		expect(state.pendingReinject).toEqual(["beta", "gamma"]);
+	});
+
+	it("clears pending when reinject is skipped", () => {
+		const runtime = createCompactionRuntime();
+		const state = createInitialState();
+		state.pendingReinject = ["alpha"];
+
+		applyPendingReinjectAfterCompact(state, runtime, false, ["beta"]);
+
+		expect(state.pendingReinject).toEqual([]);
+	});
+
+	it("keeps stale pending when manual compaction scheduled a user-prompt clear", () => {
+		const runtime = createCompactionRuntime();
+		runtime.clearPendingReinjectOnNextUserInput = true;
+		const state = createInitialState();
+		state.pendingReinject = ["alpha"];
+
+		applyPendingReinjectAfterCompact(state, runtime, false, ["beta"]);
+
+		expect(state.pendingReinject).toEqual(["alpha"]);
+	});
+});
@@ -0,0 +1,75 @@
+import { describe, expect, it } from "vitest";
+import {
+	consumeCompactionOnSessionCompact,
+	createCompactionRuntime,
+} from "../src/compaction";
+import { clearPendingReinjectOnUserPrompt, tryConsumeDeferredReinject } from "../src/reinject";
+import { createDefaultSettings } from "../src/settings";
+import { createInitialState } from "../src/state";
+
+describe("manual compaction defer clear", () => {
+	it("schedules clear on manual compaction when reinjectOnManualCompaction is false", () => {
+		const runtime = createCompactionRuntime();
+		const state = createInitialState();
+		state.pendingReinject = ["alpha"];
+		runtime.pendingCompactionSource = "manual";
+
+		const shouldReinject = consumeCompactionOnSessionCompact(runtime, state, null, createDefaultSettings());
+
+		expect(shouldReinject).toBe(false);
+		expect(runtime.clearPendingReinjectOnNextUserInput).toBe(true);
+		expect(state.pendingReinject).toEqual(["alpha"]);
+	});
+
+	it("blocks deferred inject until user prompt clears stale pending", () => {
+		const runtime = createCompactionRuntime();
+		const state = createInitialState();
+		state.pendingReinject = ["alpha"];
+		runtime.clearPendingReinjectOnNextUserInput = true;
+
+		expect(
+			tryConsumeDeferredReinject(state, createDefaultSettings(), [], undefined, runtime),
+		).toBeUndefined();
+		expect(state.pendingReinject).toEqual(["alpha"]);
+	});
+
+	it("clears pending on user prompt and allows deferred inject again", () => {
+		const runtime = createCompactionRuntime();
+		const state = createInitialState();
+		state.pendingReinject = ["alpha"];
+		runtime.clearPendingReinjectOnNextUserInput = true;
+
+		expect(clearPendingReinjectOnUserPrompt(state, runtime)).toBe(true);
+		expect(state.pendingReinject).toEqual([]);
+		expect(runtime.clearPendingReinjectOnNextUserInput).toBe(false);
+	});
+
+	it("does not schedule clear when manual compaction may reinject", () => {
+		const runtime = createCompactionRuntime();
+		const state = createInitialState();
+		state.pendingReinject = ["alpha"];
+		runtime.pendingCompactionSource = "manual";
+		const settings = createDefaultSettings();
+		settings.reinjectOnManualCompaction = true;
+
+		const shouldReinject = consumeCompactionOnSessionCompact(runtime, state, true, settings);
+
+		expect(shouldReinject).toBe(true);
+		expect(runtime.clearPendingReinjectOnNextUserInput).toBe(false);
+	});
+
+	it("clears stale manual flag when a later auto compaction enqueues reinject", () => {
+		const runtime = createCompactionRuntime();
+		const state = createInitialState();
+		runtime.clearPendingReinjectOnNextUserInput = true;
+		state.pendingReinject = ["beta"];
+		runtime.pendingCompactionSource = "auto";
+
+		const shouldReinject = consumeCompactionOnSessionCompact(runtime, state, true, createDefaultSettings());
+
+		expect(shouldReinject).toBe(true);
+		expect(runtime.clearPendingReinjectOnNextUserInput).toBe(false);
+		expect(clearPendingReinjectOnUserPrompt(state, runtime)).toBe(false);
+		expect(state.pendingReinject).toEqual(["beta"]);
+	});
+});
@@ -0,0 +1,40 @@
+import { describe, expect, it, vi } from "vitest";
+import { maybeWarnManySkills } from "../src/reinject";
+import { createDefaultSettings } from "../src/settings";
+
+describe("maybeWarnManySkills", () => {
+	it("warns above 3 when maxSkills is unset", () => {
+		const notify = vi.fn();
+		const ctx = { hasUI: true, ui: { notify } } as never;
+
+		maybeWarnManySkills(4, createDefaultSettings(), ctx);
+
+		expect(notify).toHaveBeenCalledWith(
+			"skill-reinject: re-injecting 4 tracked skills (soft warn above 3)",
+			"warning",
+		);
+	});
+
+	it("does not warn at 3 skills when maxSkills is unset", () => {
+		const notify = vi.fn();
+		const ctx = { hasUI: true, ui: { notify } } as never;
+
+		maybeWarnManySkills(3, createDefaultSettings(), ctx);
+
+		expect(notify).not.toHaveBeenCalled();
+	});
+
+	it("uses configured maxSkills threshold", () => {
+		const notify = vi.fn();
+		const ctx = { hasUI: true, ui: { notify } } as never;
+		const settings = createDefaultSettings();
+		settings.maxSkills = 2;
+
+		maybeWarnManySkills(3, settings, ctx);
+
+		expect(notify).toHaveBeenCalledWith(
+			"skill-reinject: re-injecting 3 skills (maxSkills warn threshold: 2)",
+			"warning",
+		);
+	});
+});
@@ -0,0 +1,116 @@
+import { mkdtempSync, mkdirSync, rmSync, writeFileSync } from "fs";
+import { tmpdir } from "os";
+import { join } from "path";
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { createCompactionRuntime } from "../src/compaction";
+import { DEFERRED_REINJECT_CUSTOM_TYPE, deliverDeferredReinjectSteer, tryConsumeDeferredReinject } from "../src/reinject";
+import { createDefaultSettings } from "../src/settings";
+import { createInitialState, trackSkill } from "../src/state";
+
+const tempDirs: string[] = [];
+
+afterEach(() => {
+	for (const dir of tempDirs.splice(0)) {
+		rmSync(dir, { recursive: true, force: true });
+	}
+});
+
+function tempSkillDir(name: string): { filePath: string; baseDir: string } {
+	const root = mkdtempSync(join(tmpdir(), "pi-skill-reinject-mid-turn-"));
+	tempDirs.push(root);
+	const baseDir = join(root, name);
+	mkdirSync(baseDir, { recursive: true });
+	const filePath = join(baseDir, "SKILL.md");
+	writeFileSync(filePath, `---\nname: ${name}\n---\n# body\n`, "utf8");
+	return { filePath, baseDir };
+}
+
+describe("deliverDeferredReinjectSteer", () => {
+	it("sends steer message and clears pending when skills resolve", () => {
+		const { filePath, baseDir } = tempSkillDir("alpha");
+		const runtime = createCompactionRuntime();
+		const state = createInitialState();
+		trackSkill(state, { name: "alpha", filePath, baseDir, source: "slash" });
+		state.pendingReinject = ["alpha"];
+		const sendMessage = vi.fn();
+		const pi = { sendMessage } as never;
+		const registered = [{ name: "alpha", filePath, baseDir }];
+
+		const delivered = deliverDeferredReinjectSteer(
+			pi,
+			state,
+			createDefaultSettings(),
+			registered,
+			runtime,
+			"compact-1",
+		);
+
+		expect(delivered).toBe(true);
+		expect(state.pendingReinject).toEqual([]);
+		expect(runtime.deferredDeliveredForCompactionId).toBe("compact-1");
+		expect(sendMessage).toHaveBeenCalledOnce();
+		expect(sendMessage).toHaveBeenCalledWith(
+			expect.objectContaining({
+				customType: DEFERRED_REINJECT_CUSTOM_TYPE,
+				display: true,
+				content: expect.stringContaining('<skill name="alpha"'),
+			}),
+			{ deliverAs: "steer" },
+		);
+	});
+
+	it("returns false without sendMessage when pending is empty", () => {
+		const runtime = createCompactionRuntime();
+		const state = createInitialState();
+		const sendMessage = vi.fn();
+		const pi = { sendMessage } as never;
+
+		expect(
+			deliverDeferredReinjectSteer(pi, state, createDefaultSettings(), [], runtime, "compact-1"),
+		).toBe(false);
+		expect(sendMessage).not.toHaveBeenCalled();
+	});
+});
+
+describe("tryConsumeDeferredReinject after mid-turn steer", () => {
+	it("skips before_agent_start inject when steer already delivered for compaction", () => {
+		const { filePath, baseDir } = tempSkillDir("beta");
+		const runtime = createCompactionRuntime();
+		runtime.lastCompactionEntryId = "compact-2";
+		runtime.deferredDeliveredForCompactionId = "compact-2";
+		const state = createInitialState();
+		trackSkill(state, { name: "beta", filePath, baseDir, source: "slash" });
+		state.pendingReinject = ["beta"];
+
+		expect(
+			tryConsumeDeferredReinject(
+				state,
+				createDefaultSettings(),
+				[{ name: "beta", filePath, baseDir }],
+				undefined,
+				runtime,
+			),
+		).toBeUndefined();
+	});
+
+	it("consumes pending on before_agent_start when steer did not run (idle path)", () => {
+		const { filePath, baseDir } = tempSkillDir("gamma");
+		const runtime = createCompactionRuntime();
+		runtime.lastCompactionEntryId = "compact-3";
+		const state = createInitialState();
+		trackSkill(state, { name: "gamma", filePath, baseDir, source: "slash" });
+		state.pendingReinject = ["gamma"];
+
+		const result = tryConsumeDeferredReinject(
+			state,
+			createDefaultSettings(),
+			[{ name: "gamma", filePath, baseDir }],
+			undefined,
+			runtime,
+		);
+
+		expect(result?.message.customType).toBe(DEFERRED_REINJECT_CUSTOM_TYPE);
+		expect(state.pendingReinject).toEqual([]);
+		expect(runtime.deferredDeliveredForCompactionId).toBeNull();
+	});
+});
@@ -0,0 +1,61 @@
+import { mkdtempSync, mkdirSync, rmSync, writeFileSync } from "fs";
+import { tmpdir } from "os";
+import { join } from "path";
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { reinjectNow, resolveReinjectSkillNames } from "../src/reinject";
+import { createDefaultSettings } from "../src/settings";
+import { createInitialState, trackSkill } from "../src/state";
+
+const tempDirs: string[] = [];
+
+afterEach(() => {
+	for (const dir of tempDirs.splice(0)) {
+		rmSync(dir, { recursive: true, force: true });
+	}
+});
+
+function tempSkillDir(name: string): { filePath: string; baseDir: string } {
+	const root = mkdtempSync(join(tmpdir(), "pi-skill-reinject-now-"));
+	tempDirs.push(root);
+	const baseDir = join(root, name);
+	mkdirSync(baseDir, { recursive: true });
+	const filePath = join(baseDir, "SKILL.md");
+	writeFileSync(filePath, "# skill\n", "utf8");
+	return { filePath, baseDir };
+}
+
+describe("resolveReinjectSkillNames", () => {
+	it("includes loose tracked skill when file exists and requireRegistered is false", () => {
+		const { filePath, baseDir } = tempSkillDir("loose");
+		const state = createInitialState();
+		trackSkill(state, { name: "loose", filePath, baseDir, source: "slash" });
+
+		expect(resolveReinjectSkillNames(state, createDefaultSettings(), [])).toEqual(["loose"]);
+	});
+
+	it("excludes unregistered skills when requireRegistered is true", () => {
+		const { filePath, baseDir } = tempSkillDir("strict");
+		const state = createInitialState();
+		trackSkill(state, { name: "strict", filePath, baseDir, source: "slash" });
+		const settings = createDefaultSettings();
+		settings.requireRegistered = true;
+
+		expect(resolveReinjectSkillNames(state, settings, [])).toEqual([]);
+	});
+});
+
+describe("reinjectNow loose path", () => {
+	it("sends skill block from disk for unregistered tracked skill", () => {
+		const { filePath, baseDir } = tempSkillDir("loose");
+		const state = createInitialState();
+		trackSkill(state, { name: "loose", filePath, baseDir, source: "slash" });
+		const sendUserMessage = vi.fn();
+		const pi = { sendUserMessage } as never;
+		const ctx = { hasUI: false, isIdle: () => true } as never;
+
+		reinjectNow(pi, state, createDefaultSettings(), ctx, []);
+
+		expect(sendUserMessage).toHaveBeenCalledTimes(1);
+		expect(sendUserMessage.mock.calls[0]?.[0]).toContain('<skill name="loose"');
+	});
+});
@@ -0,0 +1,81 @@
+import { mkdtempSync, mkdirSync, rmSync, writeFileSync } from "fs";
+import { tmpdir } from "os";
+import { join } from "path";
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { buildReinjectBlocks, tryConsumeDeferredReinject } from "../src/reinject";
+import { createDefaultSettings } from "../src/settings";
+import { createInitialState, trackSkill } from "../src/state";
+
+const tempDirs: string[] = [];
+
+afterEach(() => {
+	for (const dir of tempDirs.splice(0)) {
+		rmSync(dir, { recursive: true, force: true });
+	}
+});
+
+function tempSkillDir(name: string): { filePath: string; baseDir: string } {
+	const root = mkdtempSync(join(tmpdir(), "pi-skill-reinject-deferred-"));
+	tempDirs.push(root);
+	const baseDir = join(root, name);
+	mkdirSync(baseDir, { recursive: true });
+	const filePath = join(baseDir, "SKILL.md");
+	writeFileSync(filePath, "# skill\n", "utf8");
+	return { filePath, baseDir };
+}
+
+function ctxWithNotify(): { ctx: never; notify: ReturnType<typeof vi.fn> } {
+	const notify = vi.fn();
+	return { notify, ctx: { hasUI: true, ui: { notify } } as never };
+}
+
+describe("deferred reinject loose fallback", () => {
+	it("(a) unregistered on disk with requireRegistered=false → block + info notify", () => {
+		const { filePath, baseDir } = tempSkillDir("loose");
+		const state = createInitialState();
+		trackSkill(state, { name: "loose", filePath, baseDir, source: "slash" });
+		state.pendingReinject = ["loose"];
+		const { ctx, notify } = ctxWithNotify();
+
+		const result = tryConsumeDeferredReinject(state, createDefaultSettings(), [], ctx);
+
+		expect(result?.message?.content).toContain('<skill name="loose"');
+		expect(notify).toHaveBeenCalledWith('skill-reinject: re-injected "loose" from disk', "info");
+	});
+
+	it("(b) unregistered on disk with requireRegistered=true → skip + warn", () => {
+		const { filePath, baseDir } = tempSkillDir("strict");
+		const state = createInitialState();
+		trackSkill(state, { name: "strict", filePath, baseDir, source: "slash" });
+		const settings = createDefaultSettings();
+		settings.requireRegistered = true;
+		const { ctx, notify } = ctxWithNotify();
+
+		const blocks = buildReinjectBlocks(["strict"], state, settings, [], ctx);
+
+		expect(blocks).toEqual([]);
+		expect(notify).toHaveBeenCalledWith(
+			'skill-reinject: skipped "strict" — no longer registered',
+			"warning",
+		);
+	});
+
+	it("(c) missing filePath on disk → skip + warn", () => {
+		const state = createInitialState();
+		trackSkill(state, {
+			name: "missing",
+			filePath: "/no/such/SKILL.md",
+			baseDir: "/no/such",
+			source: "slash",
+		});
+		const { ctx, notify } = ctxWithNotify();
+
+		const blocks = buildReinjectBlocks(["missing"], state, createDefaultSettings(), [], ctx);
+
+		expect(blocks).toEqual([]);
+		expect(notify).toHaveBeenCalledWith(
+			'skill-reinject: skipped "missing" — SKILL.md not found on disk',
+			"warning",
+		);
+	});
+});
@@ -54,6 +54,16 @@ describe("parseSkillReinjectPartial", () => {
 			}),
 		).toEqual({ enabled: true, suffix: "custom" });
 	});
+
+	it("parses debug flag", () => {
+		expect(parseSkillReinjectPartial({ debug: true })).toEqual({ debug: true });
+	});
+
+	it("parses requireRegistered flag", () => {
+		expect(parseSkillReinjectPartial({ requireRegistered: true })).toEqual({
+			requireRegistered: true,
+		});
+	});
 });

 describe("mergeSkillReinjectSettings", () => {