feat(tools): guarded write core under the shared lock (U5, #1375)

src/core/task/Task.ts

@@ -111,6 +111,7 @@ import { buildNativeToolsArrayWithRestrictions } from "./build-tools"
 import { ToolRepetitionDetector } from "../tools/ToolRepetitionDetector"
 import { restoreTodoListForTask } from "../tools/UpdateTodoListTool"
 import { FileContextTracker } from "../context-tracking/FileContextTracker"
+import { ObservationRegistry } from "./observationRegistry"
 import { RooIgnoreController } from "../ignore/RooIgnoreController"
 import { RooProtectedController } from "../protect/RooProtectedController"
 import { type AssistantMessageContent, presentAssistantMessage } from "../assistant-message"
@@ -286,6 +287,10 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 	readonly instanceId: string
 	readonly metadata: TaskMetadata
 
+	// The observed on-disk version of each file this task has read. Declared here so the
+	// read tools can record it; a write guard later compares a token against this registry.
+	readonly observationRegistry = new ObservationRegistry()
+
 	todoList?: TodoItem[]
 
 	readonly rootTask: Task | undefined = undefined
@@ -383,6 +388,12 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 	providerRef: WeakRef<ClineProvider>
 	private readonly globalStoragePath: string
 	abort: boolean = false
+	// Monotonic cancellation counter. `abort` is a mutable flag that resumeAfterDelegation
+	// resets to false, so a write still waiting on a path chain cannot tell from `abort`
+	// alone that the task was cancelled while it waited - the flag may be back to false by
+	// the time its turn comes. Every cancellation bumps this counter, and the guarded-write
+	// path compares the value it captured when the write was queued.
+	cancellationGeneration: number = 0
 	currentRequestAbortController?: AbortController
 	/**
 	 * Controller for the waiter on an in-flight `ensureModelFetched()` call (see
@@ -3259,6 +3270,7 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 		}
 
 		this.abort = true
+		this.cancellationGeneration++
 		this.cancelAssistantMessagePersistence()
 		this.abortPromise ??= this.abortTaskOnce()
 		return this.abortPromise
@@ -3344,6 +3356,7 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 		// signals below are cancelled and a request already past those checks
 		// could still build tools and call `createMessage()`.
 		this.abort = true
+		this.cancellationGeneration++
 
 		// Cancel any in-progress HTTP request
 		try {

src/core/task/__tests__/Task.spec.ts

@@ -3208,6 +3208,54 @@ describe("Cline", () => {
 			).toHaveLength(1)
 		})
 
+		it("advances the cancellation generation on each cancellation and keeps it advanced across a resume", async () => {
+			// The S4a write guard compares the cancellation generation a queued write
+			// captured against the generation at publish time. The abort FLAG cannot do that
+			// on its own: resumeAfterDelegation() clears it, and a write that belongs to the
+			// cancelled run would then publish as if nothing had been cancelled. Only the
+			// generation keeps the two runs apart, so it must never go backwards.
+			const task = new Task({
+				provider: mockProvider,
+				apiConfiguration: mockApiConfig,
+				task: "test task",
+				startTask: false,
+			})
+			vi.spyOn(task, "dispose").mockResolvedValue(undefined)
+
+			expect(task.cancellationGeneration).toBe(0)
+
+			await task.abortTask()
+			expect(task.abort).toBe(true)
+			expect(task.cancellationGeneration).toBe(1)
+
+			await task.resumeAfterDelegation()
+			expect(task.abort).toBe(false)
+			expect(task.cancellationGeneration).toBe(1)
+
+			await task.abortTask()
+			expect(task.abort).toBe(true)
+			expect(task.cancellationGeneration).toBe(2)
+		})
+
+		it("advances the cancellation generation on disposal, without any explicit cancel", async () => {
+			// A task torn down by the host never sees abortTask(). Disposal has to raise the
+			// same generation, or a write still parked on its path chain publishes after the
+			// task is gone.
+			const task = new Task({
+				provider: mockProvider,
+				apiConfiguration: mockApiConfig,
+				task: "test task",
+				startTask: false,
+			})
+
+			expect(task.cancellationGeneration).toBe(0)
+
+			await task.dispose()
+
+			expect(task.abort).toBe(true)
+			expect(task.cancellationGeneration).toBe(1)
+		})
+
 		it("flushes pending state before TaskAborted and disposal while queue state is intact", async () => {
 			const task = new Task({
 				provider: mockProvider,

src/core/task/__tests__/observationRegistry.spec.ts

@@ -0,0 +1,108 @@
+import { describe, it, expect, vi } from "vitest"
+
+import { ObservationRegistry } from "../observationRegistry"
+
+describe("ObservationRegistry", () => {
+	it("observe → get returns the recorded version and observedAt", () => {
+		const reg = new ObservationRegistry()
+		reg.observe("/a/b/c.ts", "1:2:300:4000000000:5000000000")
+
+		const obs = reg.get("/a/b/c.ts")
+		expect(obs).toBeDefined()
+		expect(obs!.version).toBe("1:2:300:4000000000:5000000000")
+		expect(typeof obs!.observedAt).toBe("number")
+	})
+
+	it("re-observe replaces the entry with a fresh observedAt", () => {
+		vi.useFakeTimers()
+		const reg = new ObservationRegistry()
+		reg.observe("/a/b/c.ts", "v1")
+		const first = reg.get("/a/b/c.ts")!
+		expect(first.version).toBe("v1")
+
+		vi.advanceTimersByTime(50)
+		reg.observe("/a/b/c.ts", "v2")
+		const second = reg.get("/a/b/c.ts")!
+		expect(second.version).toBe("v2")
+		expect(second.observedAt).toBeGreaterThan(first.observedAt)
+
+		vi.useRealTimers()
+	})
+
+	it("has returns true for observed paths, false otherwise", () => {
+		const reg = new ObservationRegistry()
+		reg.observe("/x.ts", "t1")
+		expect(reg.has("/x.ts")).toBe(true)
+		expect(reg.has("/y.ts")).toBe(false)
+	})
+
+	it("size reflects the number of observed entries", () => {
+		const reg = new ObservationRegistry()
+		expect(reg.size).toBe(0)
+		reg.observe("/a.ts", "t1")
+		reg.observe("/b.ts", "t2")
+		expect(reg.size).toBe(2)
+	})
+
+	it("clear removes all entries and resets size to 0", () => {
+		const reg = new ObservationRegistry()
+		reg.observe("/a.ts", "t1")
+		reg.observe("/b.ts", "t2")
+		reg.clear()
+		expect(reg.size).toBe(0)
+		expect(reg.get("/a.ts")).toBeUndefined()
+		expect(reg.has("/b.ts")).toBe(false)
+	})
+
+	it("get on empty registry returns undefined", () => {
+		const reg = new ObservationRegistry()
+		expect(reg.get("/any.ts")).toBeUndefined()
+	})
+
+	it("separate instances are independent — observing in one does not appear in the other", () => {
+		const regA = new ObservationRegistry()
+		const regB = new ObservationRegistry()
+		regA.observe("/shared.ts", "v1")
+		expect(regA.get("/shared.ts")).toBeDefined()
+		expect(regB.get("/shared.ts")).toBeUndefined()
+		regB.observe("/shared.ts", "v2")
+		expect(regA.get("/shared.ts")!.version).toBe("v1")
+		expect(regB.get("/shared.ts")!.version).toBe("v2")
+	})
+
+	describe("completeness scope (S4b follow-up #46)", () => {
+		it("defaults to a complete observation when the read scope is not given", () => {
+			const reg = new ObservationRegistry()
+			reg.observe("/a/b/c.ts", "v1")
+
+			expect(reg.get("/a/b/c.ts")!.complete).toBe(true)
+		})
+
+		it("records a partial observation when the read only returned a view of the file", () => {
+			const reg = new ObservationRegistry()
+			reg.observe("/a/b/c.ts", "v1", false)
+
+			expect(reg.get("/a/b/c.ts")!.complete).toBe(false)
+		})
+
+		it("re-observing replaces the entry's completeness with the new read's scope", () => {
+			const reg = new ObservationRegistry()
+			reg.observe("/a/b/c.ts", "v1", false)
+			reg.observe("/a/b/c.ts", "v2")
+
+			const obs = reg.get("/a/b/c.ts")!
+			expect(obs.version).toBe("v2")
+			expect(obs.complete).toBe(true)
+		})
+
+		it("re-observing with a partial scope downgrades a previously complete entry", () => {
+			const reg = new ObservationRegistry()
+			reg.observe("/a/b/c.ts", "v1")
+			reg.observe("/a/b/c.ts", "v2", false)
+
+			const obs = reg.get("/a/b/c.ts")!
+			expect(obs.version).toBe("v2")
+			expect(obs.complete).toBe(false)
+		})
+	})
+})

src/core/task/observationRegistry.ts

@@ -0,0 +1,59 @@
+/**
+ * Per-task file observation registry (upstream epic #1375, phase A2).
+ *
+ * Each Task owns its own instance so parent and subtask observations are
+ * independent. The S4 guarded-write will compare these versions against the
+ * token recomputed pre-write to detect stale reads or file replacement.
+ *
+ * Pure in-memory — zero I/O, no dependencies. The S4 guarded-write consults
+ * these observations for the version check and for the completeness check that
+ * gates a full-file replacement.
+ */
+
+export interface FileObservation {
+	/** Version token derived from on-disk fs.stat (bigint mode). */
+	version: string
+	/** Millisecond timestamp when the observation was recorded. */
+	observedAt: number
+	/**
+	 * Whether the read that produced this observation returned the complete
+	 * file. A slice, line-range, truncated, or indentation-block read returns
+	 * only a view of the file; such an observation authorizes targeted edits
+	 * on the view the model saw, but never a full-file replacement.
+	 */
+	complete: boolean
+}
+
+export class ObservationRegistry {
+	private readonly entries = new Map<string, FileObservation>()
+
+	/**
+	 * Record an observation for a file at its absolute path.
+	 *
+	 * Re-observing replaces the entry with a fresh observedAt timestamp, the
+	 * new version token, and the read's completeness. `complete` defaults to
+	 * true for callers that read the whole file themselves (spec doubles,
+	 * WriteToFileTool). A caller whose read is internal to a targeted edit must
+	 * carry the model's prior completeness instead, so the tool's own read cannot
+	 * upgrade a partial read into authority for a full-file replacement.
+	 */
+	observe(absolutePath: string, version: string, complete: boolean = true): void {
+		this.entries.set(absolutePath, { version, observedAt: Date.now(), complete })
+	}
+
+	get(absolutePath: string): FileObservation | undefined {
+		return this.entries.get(absolutePath)
+	}
+
+	has(absolutePath: string): boolean {
+		return this.entries.has(absolutePath)
+	}
+
+	clear(): void {
+		this.entries.clear()
+	}
+
+	get size(): number {
+		return this.entries.size
+	}
+}