refactor(acp): reduce bridge to automation protocol

packages/fs/tool-fs/src/diff.ts

@@ -7,7 +7,7 @@
 import { structuredPatch } from 'diff'
 import type { FileDiff } from '@deepseek-ai/dsh-tools'
 
-/** Context lines shown on each side of an applied hunk (matches claude-agent-acp). */
+/** Context lines shown on each side of an applied hunk. */
 export const DIFF_CONTEXT = 3
 
 /**
@@ -15,8 +15,7 @@ export const DIFF_CONTEXT = 3
  * contextual-diff hunks. Attached opaquely (as `unknown`) on the tool result and
  * persisted with the session log — it must be JSON-serializable (the session
  * validates this at `append`), so `presentResult` reproduces the diff card on
- * replay. The producing tool owns this shape; the bridge only sees the opaque
- * `meta` and the tool narrows it back via {@link diffsFromMeta}.
+ * replay. The producing tool owns and narrows this opaque shape.
  */
 export type FsDiffMeta = { diffs: FileDiff[] }
 

packages/fs/tool-fs/src/session-cwd.ts

@@ -1,6 +1,6 @@
 /**
  * Derive the working directory a filesystem tool resolves relative paths against: the calling
- * agent's per-session workspace (`exec.agent.session.header.cwd`), so each ACP session's
+ * agent's per-session workspace (`exec.agent.session.header.cwd`), so each session's
  * `read`/`write`/`edit` act on ITS workspace, not the server's launch dir — mirroring how
  * `dsh-tool-bash` defaults a bash `workdir` to the session cwd.
  * Non-agent calls return `undefined`, leaving the fallback in the provider rather than reading

packages/fs/tool-fs/src/write.ts

@@ -125,9 +125,8 @@ export function applyWriteTool(ctx: Context, sandbox: FsSandboxSurface): void {
         after: outcome.after,
       }
     },
-    // Pure display: a diff card (an editor renders write as a new-file / full- replace diff).
-    // `oldText: null` — a call-time presenter has no access to the file's prior content, so
-    // even an overwrite renders new-file style, matching claude-agent-acp.
+    // Pure display: a diff card. A call-time presenter has no access to prior
+    // file content, so `oldText: null` also represents an overwrite here.
     presentCall(args): DiffCallView {
       return {
         card: 'diff',
@@ -136,10 +135,9 @@ export function applyWriteTool(ctx: Context, sandbox: FsSandboxSurface): void {
         locations: [{ path: args.file_path }],
       }
     },
-    // Result-time display: a `diff` card so the completed `tool_call_update` re-installs the
-    // diff rather than the model-facing result text (an ACP `tool_call_update.content` REPLACES
-    // the call's content, so a text result would clobber the pending diff card). Overwrites use
-    // applied metadata; creates and identical overwrites use the replay-safe args fallback.
+    // Result-time display repeats the diff because completed views replace the
+    // pending view. Overwrites use applied metadata; creates and identical
+    // overwrites use the replay-safe args fallback.
     presentResult(args, result: ToolResult): DiffResultView | undefined {
       if (result.isError) return undefined
       const diffs = diffsFromMeta(result.meta)

packages/fs/tool-fs/tests/diff.spec.ts

@@ -2,7 +2,7 @@
  * Unit tests for the result-time contextual-diff computation (`src/diff.ts`):
  * the pure before/after → {@link FileDiff}[] hunk builder and the defensive
  * `meta` narrowing. These pin the exact hunk reconstruction (context lines,
- * multi-hunk replaceAll, pure insertion/deletion, no-op) the ACP bridge renders.
+ * multi-hunk replaceAll, pure insertion/deletion, no-op) that UIs render.
  */
 
 import { describe, expect, it } from 'vitest'

packages/fs/tool-fs/tests/integration.spec.ts

@@ -284,8 +284,8 @@ describe('bare provider (no dsh-fs-policy)', () => {
 })
 
 // Per-session cwd: a relative file_path resolves against the calling session's workspace
-// (`exec.agent.session.header.cwd`), not the backend's config.cwd — so an ACP editor's
-// per-session dir wins, matching dsh-tool-bash.
+// (`exec.agent.session.header.cwd`), not the backend's config.cwd, so the
+// caller-selected session workspace wins, matching dsh-tool-bash.
 describe('per-session cwd', () => {
   let sessionDir: string
   beforeEach(async () => {

packages/fs/tool-fs/tests/tools.spec.ts

@@ -425,8 +425,8 @@ describe('edit tool', () => {
 })
 
 describe('tool-owned presentation (pure presentCall)', () => {
-  // presentCall is a pure display function of args (no I/O); it drives the ACP
-  // card's title/kind and the `locations` an editor follows along to.
+  // presentCall is a pure display function of args (no I/O); it drives the
+  // card's title/kind and the `locations` a UI follows along to.
   const presentCall = async (name: string, args: unknown) => {
     const { ctx } = await setup()
     return ctx.tools.get(name)?.presentCall?.(args)
@@ -478,7 +478,7 @@ describe('tool-owned presentation (pure presentCall)', () => {
 
 describe('result-time contextual diff (meta + presentResult)', () => {
   // An edit records the applied contextual hunk on `tool/result` meta, and the tool's
-  // presentResult narrows it back into a `diff` result card the bridge renders.
+  // presentResult narrows it back into a replayable `diff` result card.
   const withContext = 'a\nb\nc\nOLD\nd\ne\nf\n'
 
   it('edit: execute attaches the applied hunk as meta { diffs }', async () => {
@@ -519,9 +519,8 @@ describe('result-time contextual diff (meta + presentResult)', () => {
   })
 
   it('write CREATE: an empty applied-diff projection still falls back to the whole-file diff card', async () => {
-    // A create has no prior content, yet the completed card must be a `diff` — an
-    // ACP tool_call_update.content REPLACES the call's content, so a non-diff result would
-    // clobber the pending new-file diff.
+    // A create has no prior content, yet the completed replacement view must
+    // remain a diff instead of clobbering the pending new-file diff with text.
     const { ctx } = await setup()
     const session = { header: {} }
     const result = await call(ctx, 'write', { file_path: 'new.txt', content: 'fresh\n' }, { session })