diff --git a/src/reinject.ts b/src/reinject.ts
index 174ae66..16a7988 100644
--- a/src/reinject.ts
+++ b/src/reinject.ts
@@ -5,6 +5,7 @@ import type {
 	SessionCompactEvent,
 	Skill,
 } from "@earendil-works/pi-coding-agent";
+import { existsSync } from "node:fs";
 import { expandSkill } from "./expand.js";
 import {
 	filterSkillsNeedingReinject,
@@ -16,6 +17,13 @@ import type { ExtensionState } from "./state.js";
 
 export const DEFERRED_REINJECT_CUSTOM_TYPE = "skill-reinject:inject";
 
+function notifySkippedSkill(ctx: ExtensionContext | undefined, skillName: string, reason: string): void {
+	if (!ctx?.hasUI) {
+		return;
+	}
+	ctx.ui.notify(`skill-reinject: skipped "${skillName}" — ${reason}`, "warning");
+}
+
 /** 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));
@@ -66,25 +74,38 @@ export function buildReinjectBlocks(
 	state: ExtensionState,
 	settings: SkillReinjectSettings,
 	registeredSkills: readonly Pick<Skill, "name" | "filePath" | "baseDir">[],
+	ctx?: ExtensionContext,
 ): string[] {
 	const registeredByName = new Map(registeredSkills.map((skill) => [skill.name, skill]));
 	const blocks: string[] = [];
 	for (const name of skillNames) {
 		const tracked = state.skills.find((skill) => skill.name === name);
-		const registered = registeredByName.get(name);
-		if (!tracked || !registered) {
+		if (!tracked) {
 			continue;
 		}
-		blocks.push(
-			expandSkill(
-				{
-					name: tracked.name,
-					filePath: registered.filePath,
-					baseDir: registered.baseDir,
-				},
-				settings.suffix,
-			),
-		);
+		const registered = registeredByName.get(name);
+		if (!registered) {
+			notifySkippedSkill(ctx, name, "no longer registered");
+			continue;
+		}
+		if (!existsSync(registered.filePath)) {
+			notifySkippedSkill(ctx, name, "SKILL.md not found on disk");
+			continue;
+		}
+		try {
+			blocks.push(
+				expandSkill(
+					{
+						name: tracked.name,
+						filePath: registered.filePath,
+						baseDir: registered.baseDir,
+					},
+					settings.suffix,
+				),
+			);
+		} catch {
+			notifySkippedSkill(ctx, name, "SKILL.md not readable");
+		}
 	}
 	return blocks;
 }
@@ -95,8 +116,9 @@ export function buildDeferredReinjectContent(
 	state: ExtensionState,
 	settings: SkillReinjectSettings,
 	registeredSkills: readonly Pick<Skill, "name" | "filePath" | "baseDir">[],
+	ctx?: ExtensionContext,
 ): string {
-	return buildReinjectBlocks(pendingNames, state, settings, registeredSkills).join("\n\n");
+	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). */
@@ -106,8 +128,9 @@ export function sendImmediateReinjectIdle(
 	state: ExtensionState,
 	settings: SkillReinjectSettings,
 	registeredSkills: readonly Pick<Skill, "name" | "filePath" | "baseDir">[],
+	ctx?: ExtensionContext,
 ): void {
-	const blocks = buildReinjectBlocks(skillNames, state, settings, registeredSkills);
+	const blocks = buildReinjectBlocks(skillNames, state, settings, registeredSkills, ctx);
 	blocks.forEach((block, index) => {
 		pi.sendUserMessage(block, index === 0 ? undefined : { deliverAs: "followUp" });
 	});
@@ -120,8 +143,9 @@ export function sendImmediateReinjectAllFollowUp(
 	state: ExtensionState,
 	settings: SkillReinjectSettings,
 	registeredSkills: readonly Pick<Skill, "name" | "filePath" | "baseDir">[],
+	ctx?: ExtensionContext,
 ): void {
-	for (const block of buildReinjectBlocks(skillNames, state, settings, registeredSkills)) {
+	for (const block of buildReinjectBlocks(skillNames, state, settings, registeredSkills, ctx)) {
 		pi.sendUserMessage(block, { deliverAs: "followUp" });
 	}
 }
@@ -134,12 +158,13 @@ export function tryConsumeDeferredReinject(
 	state: ExtensionState,
 	settings: SkillReinjectSettings,
 	registeredSkills: readonly Pick<Skill, "name" | "filePath" | "baseDir">[],
+	ctx?: ExtensionContext,
 ): BeforeAgentStartEventResult | undefined {
 	if (state.pendingReinject.length === 0) {
 		return undefined;
 	}
 	const pendingNames = [...state.pendingReinject];
-	const content = buildDeferredReinjectContent(pendingNames, state, settings, registeredSkills);
+	const content = buildDeferredReinjectContent(pendingNames, state, settings, registeredSkills, ctx);
 	if (!content) {
 		state.pendingReinject = [];
 		return undefined;