refactor(snapshot): effectify SnapshotService as scoped service

Convert Snapshot from a promise-based namespace with Instance ALS reads
to an Effect service on the Instances LayerMap.

- SnapshotService with ChildProcessSpawner for git subprocess execution
  and Effect FileSystem for file operations (replaces Process.run and
  raw fs calls)
- Nothrow git helper that always returns { code, text, stderr }, with
  spawn failure details preserved in stderr
- Hourly cleanup via Effect.forkScoped + Schedule.spaced (replaces
  Scheduler.register)
- Promise facade preserved for all existing callers
- Parallelized before/after git show in diffFull
- Add worktree to InstanceContext.Shape (needed for --work-tree flag)
- Add Instance.current getter for single ALS read
- Extract repeated git config flags into GIT_CORE/GIT_CFG/GIT_CFG_QUOTE
  constants
- Platform layers (NodeChildProcessSpawner, NodeFileSystem, NodePath)
  provided directly on the service layer

packages/opencode/src/effect/instance-context.ts

@@ -1,13 +1,15 @@
-import { ServiceMap } from "effect"
-import type { Project } from "@/project/project"
+import { ServiceMap } from "effect";
+import type { Project } from "@/project/project";
 
 export declare namespace InstanceContext {
-  export interface Shape {
-    readonly directory: string
-    readonly project: Project.Info
-  }
+	export interface Shape {
+		readonly directory: string;
+		readonly worktree: string;
+		readonly project: Project.Info;
+	}
 }
 
-export class InstanceContext extends ServiceMap.Service<InstanceContext, InstanceContext.Shape>()(
-  "opencode/InstanceContext",
-) {}
+export class InstanceContext extends ServiceMap.Service<
+	InstanceContext,
+	InstanceContext.Shape
+>()("opencode/InstanceContext") {}

packages/opencode/src/effect/instances.ts

@@ -1,64 +1,83 @@
-import { Effect, Layer, LayerMap, ServiceMap } from "effect"
-import { registerDisposer } from "./instance-registry"
-import { InstanceContext } from "./instance-context"
-import { ProviderAuthService } from "@/provider/auth-service"
-import { QuestionService } from "@/question/service"
-import { PermissionService } from "@/permission/service"
-import { FileWatcherService } from "@/file/watcher"
-import { VcsService } from "@/project/vcs"
-import { FileTimeService } from "@/file/time"
-import { FormatService } from "@/format"
-import { FileService } from "@/file"
-import { SkillService } from "@/skill/skill"
-import { Instance } from "@/project/instance"
+import { Effect, Layer, LayerMap, ServiceMap } from "effect";
+import { FileService } from "@/file";
+import { FileTimeService } from "@/file/time";
+import { FileWatcherService } from "@/file/watcher";
+import { FormatService } from "@/format";
+import { PermissionService } from "@/permission/service";
+import { Instance } from "@/project/instance";
+import { VcsService } from "@/project/vcs";
+import { ProviderAuthService } from "@/provider/auth-service";
+import { QuestionService } from "@/question/service";
+import { SkillService } from "@/skill/skill";
+import { SnapshotService } from "@/snapshot";
+import { InstanceContext } from "./instance-context";
+import { registerDisposer } from "./instance-registry";
 
-export { InstanceContext } from "./instance-context"
+export { InstanceContext } from "./instance-context";
 
 export type InstanceServices =
-  | QuestionService
-  | PermissionService
-  | ProviderAuthService
-  | FileWatcherService
-  | VcsService
-  | FileTimeService
-  | FormatService
-  | FileService
-  | SkillService
+	| QuestionService
+	| PermissionService
+	| ProviderAuthService
+	| FileWatcherService
+	| VcsService
+	| FileTimeService
+	| FormatService
+	| FileService
+	| SkillService
+	| SnapshotService;
 
-function lookup(directory: string) {
-  const project = Instance.project
-  const ctx = Layer.sync(InstanceContext, () => InstanceContext.of({ directory, project }))
-  return Layer.mergeAll(
-    Layer.fresh(QuestionService.layer),
-    Layer.fresh(PermissionService.layer),
-    Layer.fresh(ProviderAuthService.layer),
-    Layer.fresh(FileWatcherService.layer).pipe(Layer.orDie),
-    Layer.fresh(VcsService.layer),
-    Layer.fresh(FileTimeService.layer).pipe(Layer.orDie),
-    Layer.fresh(FormatService.layer),
-    Layer.fresh(FileService.layer),
-    Layer.fresh(SkillService.layer),
-  ).pipe(Layer.provide(ctx))
+// NOTE: LayerMap only passes the key (directory string) to lookup, but we need
+// the full instance context (directory, worktree, project). We read from the
+// legacy Instance ALS here, which is safe because lookup is only triggered via
+// runPromiseInstance -> Instances.get, which always runs inside Instance.provide.
+// This should go away once the old Instance type is removed and lookup can load
+// the full context directly.
+function lookup(_key: string) {
+	const ctx = Layer.sync(InstanceContext, () =>
+		InstanceContext.of(Instance.current),
+	);
+	return Layer.mergeAll(
+		Layer.fresh(QuestionService.layer),
+		Layer.fresh(PermissionService.layer),
+		Layer.fresh(ProviderAuthService.layer),
+		Layer.fresh(FileWatcherService.layer).pipe(Layer.orDie),
+		Layer.fresh(VcsService.layer),
+		Layer.fresh(FileTimeService.layer).pipe(Layer.orDie),
+		Layer.fresh(FormatService.layer),
+		Layer.fresh(FileService.layer),
+		Layer.fresh(SkillService.layer),
+		Layer.fresh(SnapshotService.layer),
+	).pipe(Layer.provide(ctx));
 }
 
-export class Instances extends ServiceMap.Service<Instances, LayerMap.LayerMap<string, InstanceServices>>()(
-  "opencode/Instances",
-) {
-  static readonly layer = Layer.effect(
-    Instances,
-    Effect.gen(function* () {
-      const layerMap = yield* LayerMap.make(lookup, { idleTimeToLive: Infinity })
-      const unregister = registerDisposer((directory) => Effect.runPromise(layerMap.invalidate(directory)))
-      yield* Effect.addFinalizer(() => Effect.sync(unregister))
-      return Instances.of(layerMap)
-    }),
-  )
+export class Instances extends ServiceMap.Service<
+	Instances,
+	LayerMap.LayerMap<string, InstanceServices>
+>()("opencode/Instances") {
+	static readonly layer = Layer.effect(
+		Instances,
+		Effect.gen(function* () {
+			const layerMap = yield* LayerMap.make(lookup, {
+				idleTimeToLive: Infinity,
+			});
+			const unregister = registerDisposer((directory) =>
+				Effect.runPromise(layerMap.invalidate(directory)),
+			);
+			yield* Effect.addFinalizer(() => Effect.sync(unregister));
+			return Instances.of(layerMap);
+		}),
+	);
 
-  static get(directory: string): Layer.Layer<InstanceServices, never, Instances> {
-    return Layer.unwrap(Instances.use((map) => Effect.succeed(map.get(directory))))
-  }
+	static get(
+		directory: string,
+	): Layer.Layer<InstanceServices, never, Instances> {
+		return Layer.unwrap(
+			Instances.use((map) => Effect.succeed(map.get(directory))),
+		);
+	}
 
-  static invalidate(directory: string): Effect.Effect<void, never, Instances> {
-    return Instances.use((map) => map.invalidate(directory))
-  }
+	static invalidate(directory: string): Effect.Effect<void, never, Instances> {
+		return Instances.use((map) => map.invalidate(directory));
+	}
 }

packages/opencode/src/project/instance.ts

@@ -1,163 +1,185 @@
-import { Log } from "@/util/log"
-import { Context } from "../util/context"
-import { Project } from "./project"
-import { State } from "./state"
-import { iife } from "@/util/iife"
-import { GlobalBus } from "@/bus/global"
-import { Filesystem } from "@/util/filesystem"
-import { disposeInstance } from "@/effect/instance-registry"
+import { GlobalBus } from "@/bus/global";
+import { disposeInstance } from "@/effect/instance-registry";
+import { Filesystem } from "@/util/filesystem";
+import { iife } from "@/util/iife";
+import { Log } from "@/util/log";
+import { Context } from "../util/context";
+import { Project } from "./project";
+import { State } from "./state";
 
 interface Context {
-  directory: string
-  worktree: string
-  project: Project.Info
+	directory: string;
+	worktree: string;
+	project: Project.Info;
 }
-const context = Context.create<Context>("instance")
-const cache = new Map<string, Promise<Context>>()
+const context = Context.create<Context>("instance");
+const cache = new Map<string, Promise<Context>>();
 
 const disposal = {
-  all: undefined as Promise<void> | undefined,
-}
+	all: undefined as Promise<void> | undefined,
+};
 
 function emit(directory: string) {
-  GlobalBus.emit("event", {
-    directory,
-    payload: {
-      type: "server.instance.disposed",
-      properties: {
-        directory,
-      },
-    },
-  })
+	GlobalBus.emit("event", {
+		directory,
+		payload: {
+			type: "server.instance.disposed",
+			properties: {
+				directory,
+			},
+		},
+	});
 }
 
-function boot(input: { directory: string; init?: () => Promise<any>; project?: Project.Info; worktree?: string }) {
-  return iife(async () => {
-    const ctx =
-      input.project && input.worktree
-        ? {
-            directory: input.directory,
-            worktree: input.worktree,
-            project: input.project,
-          }
-        : await Project.fromDirectory(input.directory).then(({ project, sandbox }) => ({
-            directory: input.directory,
-            worktree: sandbox,
-            project,
-          }))
-    await context.provide(ctx, async () => {
-      await input.init?.()
-    })
-    return ctx
-  })
+function boot(input: {
+	directory: string;
+	init?: () => Promise<any>;
+	project?: Project.Info;
+	worktree?: string;
+}) {
+	return iife(async () => {
+		const ctx =
+			input.project && input.worktree
+				? {
+						directory: input.directory,
+						worktree: input.worktree,
+						project: input.project,
+					}
+				: await Project.fromDirectory(input.directory).then(
+						({ project, sandbox }) => ({
+							directory: input.directory,
+							worktree: sandbox,
+							project,
+						}),
+					);
+		await context.provide(ctx, async () => {
+			await input.init?.();
+		});
+		return ctx;
+	});
 }
 
 function track(directory: string, next: Promise<Context>) {
-  const task = next.catch((error) => {
-    if (cache.get(directory) === task) cache.delete(directory)
-    throw error
-  })
-  cache.set(directory, task)
-  return task
+	const task = next.catch((error) => {
+		if (cache.get(directory) === task) cache.delete(directory);
+		throw error;
+	});
+	cache.set(directory, task);
+	return task;
 }
 
 export const Instance = {
-  async provide<R>(input: { directory: string; init?: () => Promise<any>; fn: () => R }): Promise<R> {
-    const directory = Filesystem.resolve(input.directory)
-    let existing = cache.get(directory)
-    if (!existing) {
-      Log.Default.info("creating instance", { directory })
-      existing = track(
-        directory,
-        boot({
-          directory,
-          init: input.init,
-        }),
-      )
-    }
-    const ctx = await existing
-    return context.provide(ctx, async () => {
-      return input.fn()
-    })
-  },
-  get directory() {
-    return context.use().directory
-  },
-  get worktree() {
-    return context.use().worktree
-  },
-  get project() {
-    return context.use().project
-  },
-  /**
-   * Check if a path is within the project boundary.
-   * Returns true if path is inside Instance.directory OR Instance.worktree.
-   * Paths within the worktree but outside the working directory should not trigger external_directory permission.
-   */
-  containsPath(filepath: string) {
-    if (Filesystem.contains(Instance.directory, filepath)) return true
-    // Non-git projects set worktree to "/" which would match ANY absolute path.
-    // Skip worktree check in this case to preserve external_directory permissions.
-    if (Instance.worktree === "/") return false
-    return Filesystem.contains(Instance.worktree, filepath)
-  },
-  /**
-   * Captures the current instance ALS context and returns a wrapper that
-   * restores it when called. Use this for callbacks that fire outside the
-   * instance async context (native addons, event emitters, timers, etc.).
-   */
-  bind<F extends (...args: any[]) => any>(fn: F): F {
-    const ctx = context.use()
-    return ((...args: any[]) => context.provide(ctx, () => fn(...args))) as F
-  },
-  state<S>(init: () => S, dispose?: (state: Awaited<S>) => Promise<void>): () => S {
-    return State.create(() => Instance.directory, init, dispose)
-  },
-  async reload(input: { directory: string; init?: () => Promise<any>; project?: Project.Info; worktree?: string }) {
-    const directory = Filesystem.resolve(input.directory)
-    Log.Default.info("reloading instance", { directory })
-    await Promise.all([State.dispose(directory), disposeInstance(directory)])
-    cache.delete(directory)
-    const next = track(directory, boot({ ...input, directory }))
-    emit(directory)
-    return await next
-  },
-  async dispose() {
-    const directory = Instance.directory
-    Log.Default.info("disposing instance", { directory })
-    await Promise.all([State.dispose(directory), disposeInstance(directory)])
-    cache.delete(directory)
-    emit(directory)
-  },
-  async disposeAll() {
-    if (disposal.all) return disposal.all
+	async provide<R>(input: {
+		directory: string;
+		init?: () => Promise<any>;
+		fn: () => R;
+	}): Promise<R> {
+		const directory = Filesystem.resolve(input.directory);
+		let existing = cache.get(directory);
+		if (!existing) {
+			Log.Default.info("creating instance", { directory });
+			existing = track(
+				directory,
+				boot({
+					directory,
+					init: input.init,
+				}),
+			);
+		}
+		const ctx = await existing;
+		return context.provide(ctx, async () => {
+			return input.fn();
+		});
+	},
+	get current() {
+		return context.use();
+	},
+	get directory() {
+		return context.use().directory;
+	},
+	get worktree() {
+		return context.use().worktree;
+	},
+	get project() {
+		return context.use().project;
+	},
+	/**
+	 * Check if a path is within the project boundary.
+	 * Returns true if path is inside Instance.directory OR Instance.worktree.
+	 * Paths within the worktree but outside the working directory should not trigger external_directory permission.
+	 */
+	containsPath(filepath: string) {
+		if (Filesystem.contains(Instance.directory, filepath)) return true;
+		// Non-git projects set worktree to "/" which would match ANY absolute path.
+		// Skip worktree check in this case to preserve external_directory permissions.
+		if (Instance.worktree === "/") return false;
+		return Filesystem.contains(Instance.worktree, filepath);
+	},
+	/**
+	 * Captures the current instance ALS context and returns a wrapper that
+	 * restores it when called. Use this for callbacks that fire outside the
+	 * instance async context (native addons, event emitters, timers, etc.).
+	 */
+	bind<F extends (...args: any[]) => any>(fn: F): F {
+		const ctx = context.use();
+		return ((...args: any[]) => context.provide(ctx, () => fn(...args))) as F;
+	},
+	state<S>(
+		init: () => S,
+		dispose?: (state: Awaited<S>) => Promise<void>,
+	): () => S {
+		return State.create(() => Instance.directory, init, dispose);
+	},
+	async reload(input: {
+		directory: string;
+		init?: () => Promise<any>;
+		project?: Project.Info;
+		worktree?: string;
+	}) {
+		const directory = Filesystem.resolve(input.directory);
+		Log.Default.info("reloading instance", { directory });
+		await Promise.all([State.dispose(directory), disposeInstance(directory)]);
+		cache.delete(directory);
+		const next = track(directory, boot({ ...input, directory }));
+		emit(directory);
+		return await next;
+	},
+	async dispose() {
+		const directory = Instance.directory;
+		Log.Default.info("disposing instance", { directory });
+		await Promise.all([State.dispose(directory), disposeInstance(directory)]);
+		cache.delete(directory);
+		emit(directory);
+	},
+	async disposeAll() {
+		if (disposal.all) return disposal.all;
 
-    disposal.all = iife(async () => {
-      Log.Default.info("disposing all instances")
-      const entries = [...cache.entries()]
-      for (const [key, value] of entries) {
-        if (cache.get(key) !== value) continue
+		disposal.all = iife(async () => {
+			Log.Default.info("disposing all instances");
+			const entries = [...cache.entries()];
+			for (const [key, value] of entries) {
+				if (cache.get(key) !== value) continue;
 
-        const ctx = await value.catch((error) => {
-          Log.Default.warn("instance dispose failed", { key, error })
-          return undefined
-        })
+				const ctx = await value.catch((error) => {
+					Log.Default.warn("instance dispose failed", { key, error });
+					return undefined;
+				});
 
-        if (!ctx) {
-          if (cache.get(key) === value) cache.delete(key)
-          continue
-        }
+				if (!ctx) {
+					if (cache.get(key) === value) cache.delete(key);
+					continue;
+				}
 
-        if (cache.get(key) !== value) continue
+				if (cache.get(key) !== value) continue;
 
-        await context.provide(ctx, async () => {
-          await Instance.dispose()
-        })
-      }
-    }).finally(() => {
-      disposal.all = undefined
-    })
+				await context.provide(ctx, async () => {
+					await Instance.dispose();
+				});
+			}
+		}).finally(() => {
+			disposal.all = undefined;
+		});
 
-    return disposal.all
-  },
-}
+		return disposal.all;
+	},
+};

packages/opencode/src/snapshot/index.ts

@@ -1,416 +1,516 @@
-import path from "path"
-import fs from "fs/promises"
-import { Filesystem } from "../util/filesystem"
-import { Log } from "../util/log"
-import { Flag } from "../flag/flag"
-import { Global } from "../global"
-import z from "zod"
-import { Config } from "../config/config"
-import { Instance } from "../project/instance"
-import { Scheduler } from "../scheduler"
-import { Process } from "@/util/process"
+import {
+	NodeChildProcessSpawner,
+	NodeFileSystem,
+	NodePath,
+} from "@effect/platform-node";
+import {
+	Cause,
+	Duration,
+	Effect,
+	FileSystem,
+	Layer,
+	Schedule,
+	ServiceMap,
+	Stream,
+} from "effect";
+import { ChildProcess, ChildProcessSpawner } from "effect/unstable/process";
+import path from "path";
+import z from "zod";
+import { InstanceContext } from "@/effect/instance-context";
+import { runPromiseInstance } from "@/effect/runtime";
+import { Config } from "../config/config";
+import { Global } from "../global";
+import { Log } from "../util/log";
+
+const log = Log.create({ service: "snapshot" });
+const PRUNE = "7.days";
+
+// Common git config flags shared across snapshot operations
+const GIT_CORE = ["-c", "core.longpaths=true", "-c", "core.symlinks=true"];
+const GIT_CFG = ["-c", "core.autocrlf=false", ...GIT_CORE];
+const GIT_CFG_QUOTE = [...GIT_CFG, "-c", "core.quotepath=false"];
+
+interface GitResult {
+	readonly code: ChildProcessSpawner.ExitCode;
+	readonly text: string;
+	readonly stderr: string;
+}
 
 export namespace Snapshot {
-  const log = Log.create({ service: "snapshot" })
-  const hour = 60 * 60 * 1000
-  const prune = "7.days"
+	export const Patch = z.object({
+		hash: z.string(),
+		files: z.string().array(),
+	});
+	export type Patch = z.infer<typeof Patch>;
 
-  function args(git: string, cmd: string[]) {
-    return ["--git-dir", git, "--work-tree", Instance.worktree, ...cmd]
-  }
+	export const FileDiff = z
+		.object({
+			file: z.string(),
+			before: z.string(),
+			after: z.string(),
+			additions: z.number(),
+			deletions: z.number(),
+			status: z.enum(["added", "deleted", "modified"]).optional(),
+		})
+		.meta({
+			ref: "FileDiff",
+		});
+	export type FileDiff = z.infer<typeof FileDiff>;
 
-  export function init() {
-    Scheduler.register({
-      id: "snapshot.cleanup",
-      interval: hour,
-      run: cleanup,
-      scope: "instance",
-    })
-  }
+	// Promise facade — existing callers use these
+	export function init() {
+		void runPromiseInstance(SnapshotService.use((s) => s.init()));
+	}
 
-  export async function cleanup() {
-    if (Instance.project.vcs !== "git") return
-    const cfg = await Config.get()
-    if (cfg.snapshot === false) return
-    const git = gitdir()
-    const exists = await fs
-      .stat(git)
-      .then(() => true)
-      .catch(() => false)
-    if (!exists) return
-    const result = await Process.run(["git", ...args(git, ["gc", `--prune=${prune}`])], {
-      cwd: Instance.directory,
-      nothrow: true,
-    })
-    if (result.code !== 0) {
-      log.warn("cleanup failed", {
-        exitCode: result.code,
-        stderr: result.stderr.toString(),
-        stdout: result.stdout.toString(),
-      })
-      return
-    }
-    log.info("cleanup", { prune })
-  }
+	export async function cleanup() {
+		return runPromiseInstance(SnapshotService.use((s) => s.cleanup()));
+	}
 
-  export async function track() {
-    if (Instance.project.vcs !== "git") return
-    const cfg = await Config.get()
-    if (cfg.snapshot === false) return
-    const git = gitdir()
-    if (await fs.mkdir(git, { recursive: true })) {
-      await Process.run(["git", "init"], {
-        env: {
-          ...process.env,
-          GIT_DIR: git,
-          GIT_WORK_TREE: Instance.worktree,
-        },
-        nothrow: true,
-      })
+	export async function track() {
+		return runPromiseInstance(SnapshotService.use((s) => s.track()));
+	}
 
-      // Configure git to not convert line endings on Windows
-      await Process.run(["git", "--git-dir", git, "config", "core.autocrlf", "false"], { nothrow: true })
-      await Process.run(["git", "--git-dir", git, "config", "core.longpaths", "true"], { nothrow: true })
-      await Process.run(["git", "--git-dir", git, "config", "core.symlinks", "true"], { nothrow: true })
-      await Process.run(["git", "--git-dir", git, "config", "core.fsmonitor", "false"], { nothrow: true })
-      log.info("initialized")
-    }
-    await add(git)
-    const hash = await Process.text(["git", ...args(git, ["write-tree"])], {
-      cwd: Instance.directory,
-      nothrow: true,
-    }).then((x) => x.text)
-    log.info("tracking", { hash, cwd: Instance.directory, git })
-    return hash.trim()
-  }
+	export async function patch(hash: string) {
+		return runPromiseInstance(SnapshotService.use((s) => s.patch(hash)));
+	}
 
-  export const Patch = z.object({
-    hash: z.string(),
-    files: z.string().array(),
-  })
-  export type Patch = z.infer<typeof Patch>
+	export async function restore(snapshot: string) {
+		return runPromiseInstance(SnapshotService.use((s) => s.restore(snapshot)));
+	}
 
-  export async function patch(hash: string): Promise<Patch> {
-    const git = gitdir()
-    await add(git)
-    const result = await Process.text(
-      [
-        "git",
-        "-c",
-        "core.autocrlf=false",
-        "-c",
-        "core.longpaths=true",
-        "-c",
-        "core.symlinks=true",
-        "-c",
-        "core.quotepath=false",
-        ...args(git, ["diff", "--no-ext-diff", "--name-only", hash, "--", "."]),
-      ],
-      {
-        cwd: Instance.directory,
-        nothrow: true,
-      },
-    )
+	export async function revert(patches: Patch[]) {
+		return runPromiseInstance(SnapshotService.use((s) => s.revert(patches)));
+	}
 
-    // If git diff fails, return empty patch
-    if (result.code !== 0) {
-      log.warn("failed to get diff", { hash, exitCode: result.code })
-      return { hash, files: [] }
-    }
+	export async function diff(hash: string) {
+		return runPromiseInstance(SnapshotService.use((s) => s.diff(hash)));
+	}
 
-    const files = result.text
-    return {
-      hash,
-      files: files
-        .trim()
-        .split("\n")
-        .map((x) => x.trim())
-        .filter(Boolean)
-        .map((x) => path.join(Instance.worktree, x).replaceAll("\\", "/")),
-    }
-  }
-
-  export async function restore(snapshot: string) {
-    log.info("restore", { commit: snapshot })
-    const git = gitdir()
-    const result = await Process.run(
-      ["git", "-c", "core.longpaths=true", "-c", "core.symlinks=true", ...args(git, ["read-tree", snapshot])],
-      {
-        cwd: Instance.worktree,
-        nothrow: true,
-      },
-    )
-    if (result.code === 0) {
-      const checkout = await Process.run(
-        ["git", "-c", "core.longpaths=true", "-c", "core.symlinks=true", ...args(git, ["checkout-index", "-a", "-f"])],
-        {
-          cwd: Instance.worktree,
-          nothrow: true,
-        },
-      )
-      if (checkout.code === 0) return
-      log.error("failed to restore snapshot", {
-        snapshot,
-        exitCode: checkout.code,
-        stderr: checkout.stderr.toString(),
-        stdout: checkout.stdout.toString(),
-      })
-      return
-    }
-
-    log.error("failed to restore snapshot", {
-      snapshot,
-      exitCode: result.code,
-      stderr: result.stderr.toString(),
-      stdout: result.stdout.toString(),
-    })
-  }
-
-  export async function revert(patches: Patch[]) {
-    const files = new Set<string>()
-    const git = gitdir()
-    for (const item of patches) {
-      for (const file of item.files) {
-        if (files.has(file)) continue
-        log.info("reverting", { file, hash: item.hash })
-        const result = await Process.run(
-          [
-            "git",
-            "-c",
-            "core.longpaths=true",
-            "-c",
-            "core.symlinks=true",
-            ...args(git, ["checkout", item.hash, "--", file]),
-          ],
-          {
-            cwd: Instance.worktree,
-            nothrow: true,
-          },
-        )
-        if (result.code !== 0) {
-          const relativePath = path.relative(Instance.worktree, file)
-          const checkTree = await Process.text(
-            [
-              "git",
-              "-c",
-              "core.longpaths=true",
-              "-c",
-              "core.symlinks=true",
-              ...args(git, ["ls-tree", item.hash, "--", relativePath]),
-            ],
-            {
-              cwd: Instance.worktree,
-              nothrow: true,
-            },
-          )
-          if (checkTree.code === 0 && checkTree.text.trim()) {
-            log.info("file existed in snapshot but checkout failed, keeping", {
-              file,
-            })
-          } else {
-            log.info("file did not exist in snapshot, deleting", { file })
-            await fs.unlink(file).catch(() => {})
-          }
-        }
-        files.add(file)
-      }
-    }
-  }
-
-  export async function diff(hash: string) {
-    const git = gitdir()
-    await add(git)
-    const result = await Process.text(
-      [
-        "git",
-        "-c",
-        "core.autocrlf=false",
-        "-c",
-        "core.longpaths=true",
-        "-c",
-        "core.symlinks=true",
-        "-c",
-        "core.quotepath=false",
-        ...args(git, ["diff", "--no-ext-diff", hash, "--", "."]),
-      ],
-      {
-        cwd: Instance.worktree,
-        nothrow: true,
-      },
-    )
-
-    if (result.code !== 0) {
-      log.warn("failed to get diff", {
-        hash,
-        exitCode: result.code,
-        stderr: result.stderr.toString(),
-        stdout: result.stdout.toString(),
-      })
-      return ""
-    }
-
-    return result.text.trim()
-  }
-
-  export const FileDiff = z
-    .object({
-      file: z.string(),
-      before: z.string(),
-      after: z.string(),
-      additions: z.number(),
-      deletions: z.number(),
-      status: z.enum(["added", "deleted", "modified"]).optional(),
-    })
-    .meta({
-      ref: "FileDiff",
-    })
-  export type FileDiff = z.infer<typeof FileDiff>
-  export async function diffFull(from: string, to: string): Promise<FileDiff[]> {
-    const git = gitdir()
-    const result: FileDiff[] = []
-    const status = new Map<string, "added" | "deleted" | "modified">()
-
-    const statuses = await Process.text(
-      [
-        "git",
-        "-c",
-        "core.autocrlf=false",
-        "-c",
-        "core.longpaths=true",
-        "-c",
-        "core.symlinks=true",
-        "-c",
-        "core.quotepath=false",
-        ...args(git, ["diff", "--no-ext-diff", "--name-status", "--no-renames", from, to, "--", "."]),
-      ],
-      {
-        cwd: Instance.directory,
-        nothrow: true,
-      },
-    ).then((x) => x.text)
-
-    for (const line of statuses.trim().split("\n")) {
-      if (!line) continue
-      const [code, file] = line.split("\t")
-      if (!code || !file) continue
-      const kind = code.startsWith("A") ? "added" : code.startsWith("D") ? "deleted" : "modified"
-      status.set(file, kind)
-    }
-
-    for (const line of await Process.lines(
-      [
-        "git",
-        "-c",
-        "core.autocrlf=false",
-        "-c",
-        "core.longpaths=true",
-        "-c",
-        "core.symlinks=true",
-        "-c",
-        "core.quotepath=false",
-        ...args(git, ["diff", "--no-ext-diff", "--no-renames", "--numstat", from, to, "--", "."]),
-      ],
-      {
-        cwd: Instance.directory,
-        nothrow: true,
-      },
-    )) {
-      if (!line) continue
-      const [additions, deletions, file] = line.split("\t")
-      const isBinaryFile = additions === "-" && deletions === "-"
-      const before = isBinaryFile
-        ? ""
-        : await Process.text(
-            [
-              "git",
-              "-c",
-              "core.autocrlf=false",
-              "-c",
-              "core.longpaths=true",
-              "-c",
-              "core.symlinks=true",
-              ...args(git, ["show", `${from}:${file}`]),
-            ],
-            { nothrow: true },
-          ).then((x) => x.text)
-      const after = isBinaryFile
-        ? ""
-        : await Process.text(
-            [
-              "git",
-              "-c",
-              "core.autocrlf=false",
-              "-c",
-              "core.longpaths=true",
-              "-c",
-              "core.symlinks=true",
-              ...args(git, ["show", `${to}:${file}`]),
-            ],
-            { nothrow: true },
-          ).then((x) => x.text)
-      const added = isBinaryFile ? 0 : parseInt(additions)
-      const deleted = isBinaryFile ? 0 : parseInt(deletions)
-      result.push({
-        file,
-        before,
-        after,
-        additions: Number.isFinite(added) ? added : 0,
-        deletions: Number.isFinite(deleted) ? deleted : 0,
-        status: status.get(file) ?? "modified",
-      })
-    }
-    return result
-  }
-
-  function gitdir() {
-    const project = Instance.project
-    return path.join(Global.Path.data, "snapshot", project.id)
-  }
-
-  async function add(git: string) {
-    await syncExclude(git)
-    await Process.run(
-      [
-        "git",
-        "-c",
-        "core.autocrlf=false",
-        "-c",
-        "core.longpaths=true",
-        "-c",
-        "core.symlinks=true",
-        ...args(git, ["add", "."]),
-      ],
-      {
-        cwd: Instance.directory,
-        nothrow: true,
-      },
-    )
-  }
-
-  async function syncExclude(git: string) {
-    const file = await excludes()
-    const target = path.join(git, "info", "exclude")
-    await fs.mkdir(path.join(git, "info"), { recursive: true })
-    if (!file) {
-      await Filesystem.write(target, "")
-      return
-    }
-    const text = await Filesystem.readText(file).catch(() => "")
-
-    await Filesystem.write(target, text)
-  }
-
-  async function excludes() {
-    const file = await Process.text(["git", "rev-parse", "--path-format=absolute", "--git-path", "info/exclude"], {
-      cwd: Instance.worktree,
-      nothrow: true,
-    }).then((x) => x.text)
-    if (!file.trim()) return
-    const exists = await fs
-      .stat(file.trim())
-      .then(() => true)
-      .catch(() => false)
-    if (!exists) return
-    return file.trim()
-  }
+	export async function diffFull(from: string, to: string) {
+		return runPromiseInstance(SnapshotService.use((s) => s.diffFull(from, to)));
+	}
+}
+
+export namespace SnapshotService {
+	export interface Service {
+		readonly init: () => Effect.Effect<void>;
+		readonly cleanup: () => Effect.Effect<void>;
+		readonly track: () => Effect.Effect<string | undefined>;
+		readonly patch: (hash: string) => Effect.Effect<Snapshot.Patch>;
+		readonly restore: (snapshot: string) => Effect.Effect<void>;
+		readonly revert: (patches: Snapshot.Patch[]) => Effect.Effect<void>;
+		readonly diff: (hash: string) => Effect.Effect<string>;
+		readonly diffFull: (
+			from: string,
+			to: string,
+		) => Effect.Effect<Snapshot.FileDiff[]>;
+	}
+}
+
+export class SnapshotService extends ServiceMap.Service<
+	SnapshotService,
+	SnapshotService.Service
+>()("@opencode/Snapshot") {
+	static readonly layer = Layer.effect(
+		SnapshotService,
+		Effect.gen(function* () {
+			const ctx = yield* InstanceContext;
+			const fileSystem = yield* FileSystem.FileSystem;
+			const spawner = yield* ChildProcessSpawner.ChildProcessSpawner;
+			const { directory, worktree, project } = ctx;
+			const isGit = project.vcs === "git";
+			const snapshotGit = path.join(Global.Path.data, "snapshot", project.id);
+
+			const gitArgs = (cmd: string[]) => [
+				"--git-dir",
+				snapshotGit,
+				"--work-tree",
+				worktree,
+				...cmd,
+			];
+
+			// Run git with nothrow semantics — always returns a result, never fails
+			const git = (
+				args: string[],
+				opts?: { cwd?: string; env?: Record<string, string> },
+			): Effect.Effect<GitResult> =>
+				Effect.gen(function* () {
+					const command = ChildProcess.make("git", args, {
+						cwd: opts?.cwd,
+						env: opts?.env,
+						extendEnv: true,
+					});
+					const handle = yield* spawner.spawn(command);
+					const [text, stderr] = yield* Effect.all(
+						[
+							Stream.mkString(Stream.decodeText(handle.stdout)),
+							Stream.mkString(Stream.decodeText(handle.stderr)),
+						],
+						{ concurrency: 2 },
+					);
+					const code = yield* handle.exitCode;
+					return { code, text, stderr };
+				}).pipe(
+					Effect.scoped,
+					Effect.catch((err) =>
+						Effect.succeed({
+							code: ChildProcessSpawner.ExitCode(1),
+							text: "",
+							stderr: String(err),
+						}),
+					),
+				);
+
+			// FileSystem helpers — orDie converts PlatformError to defects
+			const exists = (p: string) => fileSystem.exists(p).pipe(Effect.orDie);
+			const mkdir = (p: string) =>
+				fileSystem.makeDirectory(p, { recursive: true }).pipe(Effect.orDie);
+			const writeFile = (p: string, content: string) =>
+				fileSystem.writeFileString(p, content).pipe(Effect.orDie);
+			const readFile = (p: string) =>
+				fileSystem
+					.readFileString(p)
+					.pipe(Effect.catch(() => Effect.succeed("")));
+			const removeFile = (p: string) =>
+				fileSystem.remove(p).pipe(Effect.catch(() => Effect.void));
+
+			// --- internal Effect helpers ---
+
+			const isEnabled = Effect.gen(function* () {
+				if (!isGit) return false;
+				const cfg = yield* Effect.promise(() => Config.get());
+				return cfg.snapshot !== false;
+			});
+
+			const excludesPath = Effect.gen(function* () {
+				const result = yield* git(
+					["rev-parse", "--path-format=absolute", "--git-path", "info/exclude"],
+					{
+						cwd: worktree,
+					},
+				);
+				const file = result.text.trim();
+				if (!file) return undefined;
+				if (!(yield* exists(file))) return undefined;
+				return file;
+			});
+
+			const syncExclude = Effect.gen(function* () {
+				const file = yield* excludesPath;
+				const target = path.join(snapshotGit, "info", "exclude");
+				yield* mkdir(path.join(snapshotGit, "info"));
+				if (!file) {
+					yield* writeFile(target, "");
+					return;
+				}
+				const text = yield* readFile(file);
+				yield* writeFile(target, text);
+			});
+
+			const add = Effect.gen(function* () {
+				yield* syncExclude;
+				yield* git([...GIT_CFG, ...gitArgs(["add", "."])], { cwd: directory });
+			});
+
+			// --- service methods ---
+
+			const cleanup = Effect.fn("SnapshotService.cleanup")(function* () {
+				if (!(yield* isEnabled)) return;
+				if (!(yield* exists(snapshotGit))) return;
+				const result = yield* git(gitArgs(["gc", `--prune=${PRUNE}`]), {
+					cwd: directory,
+				});
+				if (result.code !== 0) {
+					log.warn("cleanup failed", {
+						exitCode: result.code,
+						stderr: result.stderr,
+					});
+					return;
+				}
+				log.info("cleanup", { prune: PRUNE });
+			});
+
+			const track = Effect.fn("SnapshotService.track")(function* () {
+				if (!(yield* isEnabled)) return undefined;
+				const existed = yield* exists(snapshotGit);
+				yield* mkdir(snapshotGit);
+				if (!existed) {
+					yield* git(["init"], {
+						env: { GIT_DIR: snapshotGit, GIT_WORK_TREE: worktree },
+					});
+					yield* git([
+						"--git-dir",
+						snapshotGit,
+						"config",
+						"core.autocrlf",
+						"false",
+					]);
+					yield* git([
+						"--git-dir",
+						snapshotGit,
+						"config",
+						"core.longpaths",
+						"true",
+					]);
+					yield* git([
+						"--git-dir",
+						snapshotGit,
+						"config",
+						"core.symlinks",
+						"true",
+					]);
+					yield* git([
+						"--git-dir",
+						snapshotGit,
+						"config",
+						"core.fsmonitor",
+						"false",
+					]);
+					log.info("initialized");
+				}
+				yield* add;
+				const result = yield* git(gitArgs(["write-tree"]), { cwd: directory });
+				const hash = result.text.trim();
+				log.info("tracking", { hash, cwd: directory, git: snapshotGit });
+				return hash;
+			});
+
+			const patch = Effect.fn("SnapshotService.patch")(function* (
+				hash: string,
+			) {
+				yield* add;
+				const result = yield* git(
+					[
+						...GIT_CFG_QUOTE,
+						...gitArgs([
+							"diff",
+							"--no-ext-diff",
+							"--name-only",
+							hash,
+							"--",
+							".",
+						]),
+					],
+					{ cwd: directory },
+				);
+
+				if (result.code !== 0) {
+					log.warn("failed to get diff", { hash, exitCode: result.code });
+					return { hash, files: [] } as Snapshot.Patch;
+				}
+
+				return {
+					hash,
+					files: result.text
+						.trim()
+						.split("\n")
+						.map((x: string) => x.trim())
+						.filter(Boolean)
+						.map((x: string) => path.join(worktree, x).replaceAll("\\", "/")),
+				} as Snapshot.Patch;
+			});
+
+			const restore = Effect.fn("SnapshotService.restore")(function* (
+				snapshot: string,
+			) {
+				log.info("restore", { commit: snapshot });
+				const result = yield* git(
+					[...GIT_CORE, ...gitArgs(["read-tree", snapshot])],
+					{ cwd: worktree },
+				);
+				if (result.code === 0) {
+					const checkout = yield* git(
+						[...GIT_CORE, ...gitArgs(["checkout-index", "-a", "-f"])],
+						{ cwd: worktree },
+					);
+					if (checkout.code === 0) return;
+					log.error("failed to restore snapshot", {
+						snapshot,
+						exitCode: checkout.code,
+						stderr: checkout.stderr,
+					});
+					return;
+				}
+				log.error("failed to restore snapshot", {
+					snapshot,
+					exitCode: result.code,
+					stderr: result.stderr,
+				});
+			});
+
+			const revert = Effect.fn("SnapshotService.revert")(function* (
+				patches: Snapshot.Patch[],
+			) {
+				const seen = new Set<string>();
+				for (const item of patches) {
+					for (const file of item.files) {
+						if (seen.has(file)) continue;
+						log.info("reverting", { file, hash: item.hash });
+						const result = yield* git(
+							[...GIT_CORE, ...gitArgs(["checkout", item.hash, "--", file])],
+							{
+								cwd: worktree,
+							},
+						);
+						if (result.code !== 0) {
+							const relativePath = path.relative(worktree, file);
+							const checkTree = yield* git(
+								[
+									...GIT_CORE,
+									...gitArgs(["ls-tree", item.hash, "--", relativePath]),
+								],
+								{
+									cwd: worktree,
+								},
+							);
+							if (checkTree.code === 0 && checkTree.text.trim()) {
+								log.info(
+									"file existed in snapshot but checkout failed, keeping",
+									{ file },
+								);
+							} else {
+								log.info("file did not exist in snapshot, deleting", { file });
+								yield* removeFile(file);
+							}
+						}
+						seen.add(file);
+					}
+				}
+			});
+
+			const diff = Effect.fn("SnapshotService.diff")(function* (hash: string) {
+				yield* add;
+				const result = yield* git(
+					[
+						...GIT_CFG_QUOTE,
+						...gitArgs(["diff", "--no-ext-diff", hash, "--", "."]),
+					],
+					{
+						cwd: worktree,
+					},
+				);
+
+				if (result.code !== 0) {
+					log.warn("failed to get diff", {
+						hash,
+						exitCode: result.code,
+						stderr: result.stderr,
+					});
+					return "";
+				}
+
+				return result.text.trim();
+			});
+
+			const diffFull = Effect.fn("SnapshotService.diffFull")(function* (
+				from: string,
+				to: string,
+			) {
+				const result: Snapshot.FileDiff[] = [];
+				const status = new Map<string, "added" | "deleted" | "modified">();
+
+				const statuses = yield* git(
+					[
+						...GIT_CFG_QUOTE,
+						...gitArgs([
+							"diff",
+							"--no-ext-diff",
+							"--name-status",
+							"--no-renames",
+							from,
+							to,
+							"--",
+							".",
+						]),
+					],
+					{ cwd: directory },
+				);
+
+				for (const line of statuses.text.trim().split("\n")) {
+					if (!line) continue;
+					const [code, file] = line.split("\t");
+					if (!code || !file) continue;
+					const kind = code.startsWith("A")
+						? "added"
+						: code.startsWith("D")
+							? "deleted"
+							: "modified";
+					status.set(file, kind);
+				}
+
+				const numstat = yield* git(
+					[
+						...GIT_CFG_QUOTE,
+						...gitArgs([
+							"diff",
+							"--no-ext-diff",
+							"--no-renames",
+							"--numstat",
+							from,
+							to,
+							"--",
+							".",
+						]),
+					],
+					{ cwd: directory },
+				);
+
+				for (const line of numstat.text.trim().split("\n")) {
+					if (!line) continue;
+					const [additions, deletions, file] = line.split("\t");
+					const isBinaryFile = additions === "-" && deletions === "-";
+					const [before, after] = isBinaryFile
+						? ["", ""]
+						: yield* Effect.all(
+								[
+									git([
+										...GIT_CFG,
+										...gitArgs(["show", `${from}:${file}`]),
+									]).pipe(Effect.map((r) => r.text)),
+									git([...GIT_CFG, ...gitArgs(["show", `${to}:${file}`])]).pipe(
+										Effect.map((r) => r.text),
+									),
+								],
+								{ concurrency: 2 },
+							);
+					const added = isBinaryFile ? 0 : parseInt(additions!);
+					const deleted = isBinaryFile ? 0 : parseInt(deletions!);
+					result.push({
+						file: file!,
+						before,
+						after,
+						additions: Number.isFinite(added) ? added : 0,
+						deletions: Number.isFinite(deleted) ? deleted : 0,
+						status: status.get(file!) ?? "modified",
+					});
+				}
+				return result;
+			});
+
+			// Start hourly cleanup fiber — scoped to instance lifetime
+			yield* cleanup().pipe(
+				Effect.catchCause((cause) => {
+					log.error("cleanup loop failed", { cause: Cause.pretty(cause) });
+					return Effect.void;
+				}),
+				Effect.repeat(Schedule.spaced(Duration.hours(1))),
+				Effect.forkScoped,
+			);
+
+			return SnapshotService.of({
+				init: Effect.fn("SnapshotService.init")(function* () {}),
+				cleanup,
+				track,
+				patch,
+				restore,
+				revert,
+				diff,
+				diffFull,
+			});
+		}),
+	).pipe(
+		Layer.provide(NodeChildProcessSpawner.layer),
+		Layer.provide(NodeFileSystem.layer),
+		Layer.provide(NodePath.layer),
+	);
 }

packages/opencode/test/fixture/instance.ts

@@ -1,14 +1,14 @@
-import { ConfigProvider, Layer, ManagedRuntime } from "effect"
-import { InstanceContext } from "../../src/effect/instance-context"
-import { Instance } from "../../src/project/instance"
+import { ConfigProvider, Layer, ManagedRuntime } from "effect";
+import { InstanceContext } from "../../src/effect/instance-context";
+import { Instance } from "../../src/project/instance";
 
 /** ConfigProvider that enables the experimental file watcher. */
 export const watcherConfigLayer = ConfigProvider.layer(
-  ConfigProvider.fromUnknown({
-    OPENCODE_EXPERIMENTAL_FILEWATCHER: "true",
-    OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER: "false",
-  }),
-)
+	ConfigProvider.fromUnknown({
+		OPENCODE_EXPERIMENTAL_FILEWATCHER: "true",
+		OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER: "false",
+	}),
+);
 
 /**
  * Boot an Instance with the given service layers and run `body` with
@@ -19,29 +19,35 @@ export const watcherConfigLayer = ConfigProvider.layer(
  * Pass extra layers via `options.provide` (e.g. ConfigProvider.layer).
  */
 export function withServices<S>(
-  directory: string,
-  layer: Layer.Layer<S, any, InstanceContext>,
-  body: (rt: ManagedRuntime.ManagedRuntime<S, never>) => Promise<void>,
-  options?: { provide?: Layer.Layer<never>[] },
+	directory: string,
+	layer: Layer.Layer<S, any, InstanceContext>,
+	body: (rt: ManagedRuntime.ManagedRuntime<S, never>) => Promise<void>,
+	options?: { provide?: Layer.Layer<never>[] },
 ) {
-  return Instance.provide({
-    directory,
-    fn: async () => {
-      const ctx = Layer.sync(InstanceContext, () =>
-        InstanceContext.of({ directory: Instance.directory, project: Instance.project }),
-      )
-      let resolved: Layer.Layer<S> = Layer.fresh(layer).pipe(Layer.provide(ctx)) as any
-      if (options?.provide) {
-        for (const l of options.provide) {
-          resolved = resolved.pipe(Layer.provide(l)) as any
-        }
-      }
-      const rt = ManagedRuntime.make(resolved)
-      try {
-        await body(rt)
-      } finally {
-        await rt.dispose()
-      }
-    },
-  })
+	return Instance.provide({
+		directory,
+		fn: async () => {
+			const ctx = Layer.sync(InstanceContext, () =>
+				InstanceContext.of({
+					directory: Instance.directory,
+					worktree: Instance.worktree,
+					project: Instance.project,
+				}),
+			);
+			let resolved: Layer.Layer<S> = Layer.fresh(layer).pipe(
+				Layer.provide(ctx),
+			) as any;
+			if (options?.provide) {
+				for (const l of options.provide) {
+					resolved = resolved.pipe(Layer.provide(l)) as any;
+				}
+			}
+			const rt = ManagedRuntime.make(resolved);
+			try {
+				await body(rt);
+			} finally {
+				await rt.dispose();
+			}
+		},
+	});
 }