refactor(acp): reduce bridge to automation protocol

.agents/notes/implemented/architecture/2026-07-02-tool-render-intent-union.md

@@ -2,6 +2,8 @@
 
 Status: implemented
 
+> The render-intent union remains current for UI transports; its ACP mapping is superseded by [ACP as an automation-only protocol](../simplification/2026-07-23-acp-automation-only-protocol.md).
+
 ## Problem
 
 A tool declares how its calls render in a UI (an editor's tool-call card) through two callbacks, `presentCall`/`presentResult` on `ToolDefinition`, returning `ToolCallPresentation` / `ToolResultPresentation` with an optional `ToolTerminal` sub-shape. These grew incrementally into a **bag of optional fields**: `title`, `kind`, `rawInput`, `content`, `locations`, `terminal` on the call; `title`, `content`, `terminal` on the result; `cwd`/`output`/`exitCode`/`signal` on `ToolTerminal`. The split of responsibility is muddy:
@@ -10,7 +12,7 @@ A tool declares how its calls render in a UI (an editor's tool-call card) throug
 - Which combinations are *valid* is unwritten: a `terminal` call that also sets `content` means "description above the card"; a generic call that sets `terminal` is meaningless but representable. The type permits nonsense.
 - There is no way to express the one file-tool affordance an editor most wants — a **diff card** (`{path, oldText, newText}`, which Zed renders as an inline diff / new-file preview). `ToolCallPresentation.content` is the *LLM* `ContentBlock[]` vocabulary (text/image), so a tool literally cannot ask for a diff.
 
-The existing `FIXME(tool-presentation)` in `packages/core/tools/src/index.ts` named the fix: "redesign the type so a tool declares its render INTENT once (e.g. a tagged union over card kinds) rather than a bag of optional fields the bridge stitches together." The rejected Agent Note [Collapse tool-owned UI presentation](../../rejected/simplification/2026-06-20-generic-tool-rendering.md) deferred it explicitly: rich rendering "should return later as a tagged render-intent union after there are at least two real tools and two real consumers to validate the vocabulary." That bar is now met — two producer families (`dsh-tool-bash`, `dsh-tool-fs`) and two consumers (the ACP bridge live path + the snapshot replay path).
+The existing `FIXME(tool-presentation)` in `packages/core/tools/src/index.ts` named the fix: "redesign the type so a tool declares its render INTENT once (e.g. a tagged union over card kinds) rather than a bag of optional fields the bridge stitches together." The rejected Agent Note [Collapse tool-owned UI presentation](../../rejected/simplification/2026-06-20-generic-tool-rendering.md) deferred it explicitly: rich rendering "should return later as a tagged render-intent union after there are at least two real tools and two real consumers to validate the vocabulary." That bar is met by multiple producer families plus the TUI and JSON-RPC/Web consumers.
 
 ## Decision
 
@@ -37,8 +39,8 @@ interface TerminalResultView { card: 'terminal'; title?: string; output?: string
 ### Why a tagged union beats the field-bag
 
 - **Invalid states become unrepresentable.** A generic card cannot carry terminal output; a terminal card cannot carry a diff. The old bag permitted all of these.
-- **The bridge switches instead of stitching.** One arm per card kind, each producing exactly the wire shape that card needs, rather than reconciling five optional fields whose interactions are undocumented.
-- **`diff` is a first-class intent.** `dsh-tool-fs` write/edit declare `card:'diff'`; the bridge emits an ACP `{type:'diff', path, oldText, newText}` `ToolCallContent` (already in the SDK's `ToolCallContent` union, previously unused by the bridge). This is the affordance the redesign unlocks.
+- **Consumers switch instead of stitching.** One arm per card kind produces exactly the view that card needs, rather than reconciling five optional fields whose interactions are undocumented.
+- **`diff` is a first-class intent.** `dsh-tool-fs` write/edit declare `card:'diff'` with `{path, oldText, newText}`, allowing capable UIs to render an inline change without tool-name special cases.
 
 ### Producer mapping
 
@@ -54,10 +56,6 @@ interface TerminalResultView { card: 'terminal'; title?: string; output?: string
 
 `presentCall`/`presentResult` remain pure functions of `args` (+ the result for `presentResult`) — they run on live streaming AND session-log replay, so they must be replay-deterministic. Every view is derived from args alone: write's diff is new-file style (`oldText:null`) because the tool has no old content at call time; edit's diff is `old_string`→`new_string`.
 
-## Relative-path display titles
-
-`claude-agent-acp` relativizes a file card's title path against the session cwd (`toDisplayPath`) — `Read src/foo.ts`, not `/abs/proj/src/foo.ts` — while keeping `locations[]`/`diff.path` **raw** (the editor opens the real path). Our `presentCall` is pure/args-only and cannot see the session cwd, so this relativization happens at the **bridge**, which already threads the session cwd into tool-call rendering (the same cwd it uses to resolve a terminal card's header). The bridge relativizes the title only, by an exact structured replace of the known `locations[0].path`/`diffs[0].path` substring — generic over the file-card kinds, never special-casing tool names.
-
 ## Alternatives considered
 
 - **Delete tool-owned presentation entirely** — [the rejected collapse proposal](../../rejected/simplification/2026-06-20-generic-tool-rendering.md); its own verdict deferred to exactly this union once two real tools and two real consumers existed, and that bar is now met.
@@ -76,5 +74,4 @@ A new render intent is a compile-breaking change at the bridge switch — delibe
 
 - Supersedes the deferral in [Collapse tool-owned UI presentation](../../rejected/simplification/2026-06-20-generic-tool-rendering.md) (rejected — "wait for two real tools and two real consumers, then a tagged render-intent union"). That bar is now met; this is that union.
 - Extended by [Result-time applied-hunk diffs](2026-07-02-result-time-applied-hunk-diffs.md), which adds a persisted `meta` channel so write/edit emit a result-time `DiffResultView` — the applied change (a contextual hunk with context lines / one per `replace_all` site, or a whole-file diff for a create) — on top of this union's call-time diff card.
-- Folds `ToolTerminal` into the `terminal` views described by [ACP terminal and tool-call rendering](../feature/2026-06-18-acp-terminal-and-tool-rendering.md) (the `_meta` terminal-card convention and capability gate are unchanged; only the harness-side presentation type changes).
-- The ACP SDK's `Diff` / `ToolCallContent` types back the new `diff` card.
+- Folds `ToolTerminal` into the tagged `terminal` views used by current UI transports.