docs(tools): DiffResultView.diffs may be a whole-file diff, not only hunks

The write-diff-card fix made write's presentResult return an args-derived
whole-file diff (oldText:null) for a create / unchanged overwrite, but the
DiffResultView contract and its mirrored docs still said `diffs` is ALWAYS
the applied contextual hunks computed from before/after. Correct the type
JSDoc, the write execute-side comment, and the four mirrored surfaces
(tools.md, tools README, acp-feature-support, adding-a-tool cookbook) to
say: typically the applied hunks, or a whole-file diff when there is no
before-image (a create) — and that a mutation returns the diff result even
when it duplicates the call-time card, since a tool_call_update.content
replace would otherwise clobber the diff with the model-facing text.
Regenerate the cordis catalog (source line shift).

docs/cookbook/adding-a-tool.md

@@ -59,7 +59,7 @@ Both methods return a **`card`-tagged render intent** — pick the card kind tha
   - `{ card: 'generic', title, kind?, rawInput?, content?, locations? }` — the default. Set `kind` for an icon (`read`/`search`/…); set `locations: [{ path, line? }]` for any file your tool touches so a capable editor follows along / jumps to it.
   - `{ card: 'terminal', title, description?, cwd? }` — your call IS a shell command. `title` is the command, `description` renders above the terminal card. (tool-bash.)
   - `{ card: 'diff', title, diffs, locations? }` — your call creates or modifies a file. `diffs: [{ path, oldText, newText }]` (`oldText: null` for a new file) renders as an inline diff card. (tool-fs `write`/`edit`.)
-- `presentResult(args, { content, isError, meta? })` → a `ToolResultView` (the COMPLETED card): `{ card: 'generic', title?, content? }`, `{ card: 'terminal', title?, output?, exitCode?, signal? }` (the run's captured output + exit — the bridge shows an exit pill and derives a fenced ` ```console ` fallback for editors without the terminal capability), or `{ card: 'diff', title?, diffs }` (the APPLIED hunks of a completed file mutation, computed from the before/after content — `write`/`edit` attach the hunks via the `meta` channel and read them back here). `result.meta` is your tool's own optional presentation payload, attached from `execute` (see below) and persisted so a replay reproduces the card.
+- `presentResult(args, { content, isError, meta? })` → a `ToolResultView` (the COMPLETED card): `{ card: 'generic', title?, content? }`, `{ card: 'terminal', title?, output?, exitCode?, signal? }` (the run's captured output + exit — the bridge shows an exit pill and derives a fenced ` ```console ` fallback for editors without the terminal capability), or `{ card: 'diff', title?, diffs }` (a completed file mutation — the applied hunks computed from the before/after content when there is a before-image, else a whole-file diff for a create; `write`/`edit` attach the hunks via the `meta` channel and read them back here). A mutation tool returns the `diff` result even when it duplicates the call-time card, because an ACP `tool_call_update.content` REPLACES the call's content — a non-diff result would clobber the pending diff. `result.meta` is your tool's own optional presentation payload, attached from `execute` (see below) and persisted so a replay reproduces the card.
 
 Hard rules (they bite if broken):
 

docs/cordis-catalog/events-and-services.md

@@ -547,7 +547,7 @@ async execute(exec: ToolExecution): Promise<ToolExecutionResult>
 
 Types: [ToolDefinition](../core-data-structures/tools.md) · [ToolExecution](../core-data-structures/tools.md) · [ToolExecutionResult](../core-data-structures/tools.md)
 
-Source: [`packages/core/tools/src/index.ts:363`](../../packages/core/tools/src/index.ts)
+Source: [`packages/core/tools/src/index.ts:365`](../../packages/core/tools/src/index.ts)
 
 ## Inherited tier (cordis core + loader/hmr/timer)
 

docs/core-data-structures/tools.md

@@ -117,7 +117,7 @@ A waterfall listener receives `(exec, next)`: call `next()` to proceed (possibly
 How a tool wants its call shown in a UI (an editor tool-call card, a CLI log line), provider-neutral so a tool describes itself without depending on any client protocol. `presentCall`/`presentResult` return a **`card`-tagged render intent** — a discriminated union a UI bridge switches on:
 
 - `ToolCallView` (pending): `{ card: 'generic', title, kind?, rawInput?, content?, locations? }` (the default card; `locations` is `{ path, line? }[]` files the call reads/modifies, for editor follow-along), `{ card: 'terminal', title, description?, cwd? }` (a shell command → a terminal card), or `{ card: 'diff', title, diffs, locations? }` (a file create/modify → an inline diff card; `diffs` is `{ path, oldText, newText }[]`, `oldText: null` for a new file).
-- `ToolResultView` (completed): `{ card: 'generic', title?, content? }`, `{ card: 'terminal', title?, output?, exitCode?, signal? }` (the captured run output + exit; a capable UI shows an exit-status pill, an incapable one gets a fenced ` ```console ` fallback the bridge derives from `output`), or `{ card: 'diff', title?, diffs }` (a completed file mutation → the APPLIED hunks with context lines, one entry per changed site, computed from the before/after file content — distinct from the call-time whole-snippet `diff`, which it supersedes).
+- `ToolResultView` (completed): `{ card: 'generic', title?, content? }`, `{ card: 'terminal', title?, output?, exitCode?, signal? }` (the captured run output + exit; a capable UI shows an exit-status pill, an incapable one gets a fenced ` ```console ` fallback the bridge derives from `output`), or `{ card: 'diff', title?, diffs }` (a completed file mutation → the change to show, typically the applied hunks with context lines computed from the before/after content, or a whole-file diff when there is no before-image — e.g. a file create. A `tool_call_update`'s content REPLACES the call's content, so a mutation tool returns this even when it duplicates the call-time snippet, to keep the result from clobbering the diff with result text).
 
 `ToolCallKind` (`'read' | 'edit' | 'delete' | 'move' | 'search' | 'execute' | 'fetch' | 'other'`) picks an icon on a generic card. `FileLocation` (`{ path, line? }`) and `FileDiff` (`{ path, oldText, newText }`) are the shared file-card vocabulary. The design is pinned in [the render-intent-union RFC](../rfc/implemented/architecture/2026-07-02-tool-render-intent-union.md); the ACP bridge maps a `diff` card to a `{ type: 'diff' }` content block, a `terminal` card to the `_meta` terminal convention, and relativizes a file card's title against the session cwd.
 

packages/core/tools/README.md

@@ -79,7 +79,7 @@ A tool owns how ITS calls render in a UI (an editor's tool-call card, a CLI log
 - `presentResult(args, result): ToolResultView | undefined` — the COMPLETED state, given the same `args` and the `{ content, isError, meta? }` result, one of:
   - `{ card: 'generic', title?, content? }` — an optional replacement `title` and reformatted `content`.
   - `{ card: 'terminal', title?, output?, exitCode?, signal? }` — a terminal run's captured `output` and exit status. A capable UI shows an exit-status pill; an incapable UI gets a fenced ` ```console ` fallback the BRIDGE derives from `output` (the tool does not encode the fences).
-  - `{ card: 'diff', title?, diffs }` — a completed file mutation as an inline diff. `diffs` is `FileDiff[]` — the APPLIED hunks with surrounding context (one entry per changed site), computed from the before/after file content, distinct from the call-time whole-snippet `diff`. Used by `write`/`edit`; a `tool_call_update.content` replaces the call's content, so this supersedes the pending snippet.
+  - `{ card: 'diff', title?, diffs }` — a completed file mutation as an inline diff. `diffs` is `FileDiff[]` — typically the applied hunks with surrounding context computed from the before/after content, or a whole-file diff (`oldText: null`) when there is no before-image (a file create). Used by `write`/`edit`; a `tool_call_update.content` replaces the call's content, so a mutation tool returns this even when it duplicates the call-time snippet (else the result text would clobber the pending diff).
 
 Returning `undefined` (or omitting a method) tells a UI to fall back to a generic presentation (title = tool name, raw args as input, raw result content). Both methods must be **pure and side-effect-free**: a UI may call them during live streaming AND during a session-log replay, so they depend only on their arguments. `result.meta` is the tool's own optional presentation payload (opaque `unknown`, JSON-serializable), attached by `execute` (see below) and persisted on the `tool/result` event, so a `presentResult` reading it stays replay-deterministic (the same `meta` is read back from the log). With `defineTool`, `args` is the typed `InferArgs<S>` shape; the helper soft-validates before calling (a malformed/older logged arg shape yields `undefined` rather than throwing, since display must never crash a replay). The views are provider-neutral — the ACP bridge (`dsh-acp`) maps each `card` to ACP `tool_call`/`tool_call_update` wire fields (a `diff` card to a `{ type: 'diff' }` content block, a `terminal` card to the `_meta` terminal convention), and relativizes a file card's title against the session cwd. See the render-intent-union RFC (`docs/rfc/implemented/architecture/2026-07-02-tool-render-intent-union.md`) and the applied-hunk-diffs RFC (`docs/rfc/implemented/architecture/2026-07-02-result-time-applied-hunk-diffs.md`); `dsh-tool-bash` (terminal) and `dsh-tool-fs` (diff/generic) are the reference implementations.
 

packages/core/tools/src/index.ts

@@ -220,19 +220,21 @@ export interface TerminalResultView {
 
 /**
  * A completed file mutation rendered as an inline diff card, the *result-time*
- * analogue of {@link DiffCallView}. Set by a tool whose `execute` applied a
- * file change (e.g. `write`, `edit`): `diffs` are the APPLIED hunks computed
- * from the before/after file content (one entry per hunk, each with surrounding
- * context lines), so the editor shows the real change with context — distinct
- * from the call-time whole-snippet {@link DiffCallView}. A `tool_call_update`'s
- * content REPLACES the call's content in an editor, so this result diff
- * supersedes the pending snippet.
+ * analogue of {@link DiffCallView}. Set by a tool whose `execute` applied a file
+ * change (e.g. `write`, `edit`): `diffs` are the change to show — typically the
+ * APPLIED hunks computed from the before/after content (one entry per hunk, each
+ * with surrounding context lines), so the editor shows the real change in place;
+ * a tool with no before-image (e.g. a file create) may instead give a whole-file
+ * diff (`oldText: null`). A `tool_call_update`'s content REPLACES the call's
+ * content in an editor, so a mutation tool returns this even when it duplicates
+ * the call-time snippet — otherwise the model-facing result text would replace
+ * (clobber) the pending diff card.
  */
 export interface DiffResultView {
   card: 'diff'
   /** Replacement title for the completed call. Omit to keep the pending-state title. */
   title?: string
-  /** One entry per applied hunk (a contextual diff), in file order. */
+  /** The change to show, in file order — applied contextual hunks, or a whole-file diff when there is no before-image. */
   diffs: FileDiff[]
 }
 

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

@@ -62,9 +62,10 @@ export function applyWriteTool(ctx: Context): void {
       const outcome = await ctx.fs.writeText(target, input.content, intent, exec.signal)
       // Record the observed version (a no-op when no policy plugin listens).
       ctx.emit('fs/observed', target, outcome.version, exec)
-      // Result-time contextual diff ONLY for an overwrite (a before-version
+      // Attach a contextual hunk as `meta` ONLY for an overwrite (a before-version
       // exists). A create has no "before" — `outcome.before` is null — so it
-      // carries no result diff, leaving just the call-time whole-file card.
+      // carries no `meta`; `presentResult` then renders a whole-file diff from the
+      // args, so the completed card is still a diff (never the result text).
       const diffs = outcome.before !== null ? computeHunkDiffs(input.filePath, outcome.before, outcome.after) : []
       return {
         content: [{ type: 'text', text: formatWriteOutput(target.displayPath, outcome) }],

packages/ui/acp/acp-feature-support.md

@@ -99,7 +99,7 @@ Tool-call presentation is **owned by each tool** (`presentCall` / `presentResult
 | `ToolCallKind` mapping | S | ✅ | ✅ | ✅ | `execute`/`read`/`edit`/`other` inferred from the tool; richer mapping possible. |
 | `ToolCallStatus` | S | ✅ | ✅ | ✅ | `in_progress` → `completed`/`failed`. |
 | `content` blocks | S | ✅ | ✅ | ✅ | Text content; the description renders above the card. |
-| `diff` content | S | ✅ | ✅ | ✅ | The `write`/`edit` tools declare a `diff` render intent: `presentCall` → a call-time `{ card: 'diff' }` snippet, and `presentResult` → a result-time `{ card: 'diff' }` carrying the APPLIED hunk with surrounding context lines (one hunk per `replace_all` site), computed from the before/after file text and persisted on the `tool/result` event. The bridge emits `{ type: 'diff', path, oldText, newText }` content blocks; the result hunk supersedes the call snippet. |
+| `diff` content | S | ✅ | ✅ | ✅ | The `write`/`edit` tools declare a `diff` render intent: `presentCall` → a call-time `{ card: 'diff' }` snippet, and `presentResult` → a result-time `{ card: 'diff' }`. For an edit or an overwrite it carries the applied hunk(s) with surrounding context (one per `replace_all` site), computed from the before/after text and persisted on the `tool/result` event as `meta`; for a create (no before-image) it is an args-derived whole-file diff. The bridge emits `{ type: 'diff', path, oldText, newText }` content blocks; a successful mutation ALWAYS returns the result diff (an ACP `tool_call_update.content` replaces the call's content, so the result diff — not the model-facing text — is what survives). |
 | `terminal` content | S | ✅ | ✅ | ✅ | Via the Zed `_meta` terminal convention (see below), not the spec `terminal/*` sub-protocol. |
 | `locations` (follow-along) | S | ✅ | ✅ | ✅ | The `read`/`write`/`edit` tools emit `{ path, line? }` file-location hints via `presentCall`. |
 | `rawInput` | S | ✅ | ⚠️ | ✅ | Parsed tool args surfaced as `rawInput`. |