fix(acp): address review of the terminal-card alignment (exit parse, background/error, capability snapshot)

Codex + an independent review pass found three real defects in the prior commit:

1. parseExitStatus could misreport a SUCCESSFUL command as a failure: a clean
   exit 0 appends no marker, so output ending in "[exit code: 5]" (no trailing
   newline) was read as the marker. Anchor the parse to a LEADING newline —
   renderResult always inserts one before a real marker, so a body that merely
   ends in marker-like text no longer matches. A narrow residual (a clean exit 0
   whose final line is exactly the marker) is inherent to the replay-only-sees-
   text design and documented; the complete fix (a structured exit on the event)
   is the RFC's named escape hatch.

2. A run_in_background start and an isError result were rendered as exited
   terminal cards with a false exit-0 pill. A background start returns a task-id
   ack (not a streamed terminal) and is no longer marked terminal; an isError
   result (spawn failure / abort) carries no exit pill.

3. The terminal capability was re-read live on the result path, so a second
   initialize between a call and its result could desync them (orphan
   terminal_output or clobbered card). Snapshot the capability per session at
   creation (SessionRecord.terminalEnabled) so call and result always agree.

Also reword the reference-parity claim: keeping the description as a content
block in terminal mode is a DELIBERATE divergence (claude-agent-acp drops it).
Tests added for each; with-key e2e still green.
This commit is contained in:
Tianyi Cui
2026-06-18 19:35:15 +08:00
parent e51dabbb8b
commit 9f6b96c555
6 changed files with 152 additions and 35 deletions

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@@ -6,7 +6,7 @@ Status: implemented
The ACP bridge lets each tool own its call rendering via `presentCall`/`presentResult` (see [tool-call UI presentation](../proposed/2026-06-14-acp-agent-client-protocol.md) and `packages/tools`). For `bash` we surface the exact command as the `tool_call` title, the model's `description` as a content text block, `kind: 'execute'`, and the completed output wrapped in a fenced ` ```console ` text block.
That is a correct, capability-free baseline, but not how the reference editors render a *terminal* tool at its best. An editor like Zed has a dedicated terminal tool-call card — a header showing the working directory, the command as the label, the command output rendered as a terminal, and an exit-status pill — but it only builds that card when the `tool_call` carries terminal metadata (below). With a plain text block the output appears as static markdown and there is no cwd header. (Zed also HIDES `rawInput` for `kind: 'execute'`, which is why the command IS the title — both reference adapters do the same — and the human-readable description rides as a separate content block, since a terminal card has no description slot.)
That is a correct, capability-free baseline, but not how the reference editors render a *terminal* tool at its best. An editor like Zed has a dedicated terminal tool-call card — a header showing the working directory, the command as the label, the command output rendered as a terminal, and an exit-status pill — but it only builds that card when the `tool_call` carries terminal metadata (below). With a plain text block the output appears as static markdown and there is no cwd header. (Zed also HIDES `rawInput` for `kind: 'execute'`, which is why the command IS the title — both reference adapters do the same. The human-readable description rides as a separate content block above the card; note this is a DELIBERATE divergence — claude-agent-acp DROPS the description in terminal mode and renders only the card — we keep the summary visible alongside.)
## Key finding: agent-executed terminals use a `_meta` convention, NOT `terminal/create`

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@@ -141,6 +141,17 @@ interface SessionRecord {
* tool state.
*/
presenter: ToolPresenter
/**
* Whether THIS session renders shell tools as terminal cards — snapshotted
* from the client's `_meta.terminal_output` capability at session creation
* (`session/new`/`session/load`), NOT re-read live. A capability snapshot per
* session means the `tool_call` (which registers the terminal) and the matching
* `tool_call_update` (which streams its output) ALWAYS agree, even if a later
* `initialize` mutates the connection-level capability between them — otherwise
* a re-`initialize` mid-call could orphan a `terminal_output` (call non-terminal,
* result terminal) or clobber the card (call terminal, result non-terminal).
*/
terminalEnabled: boolean
/**
* The in-flight `session/prompt`, or `undefined` when none is pending. A
* prompt resolves with a {@link StopReason} or rejects with an Error (a
@@ -290,7 +301,7 @@ export function apply(ctx: Context, config: AcpConfig): void {
const rec = sessions.get(session.header.id)
if (rec === undefined) return
streamSessionEventUpdate(rec.sessionId, event, notify, rec.presenter, {
enabled: terminalOutputCap,
enabled: rec.terminalEnabled,
cwd: session.header.cwd,
})
const inflight = rec.inflight
@@ -422,7 +433,7 @@ export function apply(ctx: Context, config: AcpConfig): void {
agentOptions: agentOptions(config),
})
bySession.set(agent, sessionId)
sessions.set(sessionId, { sessionId, agent, presenter: makePresenter(), inflight: undefined })
sessions.set(sessionId, { sessionId, agent, presenter: makePresenter(), terminalEnabled: terminalOutputCap, inflight: undefined })
return Promise.resolve({ sessionId })
},
@@ -475,7 +486,13 @@ export function apply(ctx: Context, config: AcpConfig): void {
throw invalidParams('connection closed during session/load')
}
bySession.set(agent, params.sessionId)
const record: SessionRecord = { sessionId: params.sessionId, agent, presenter: makePresenter(), inflight: undefined }
// Snapshot the terminal capability ONCE for this session (used by both
// the replay below and the post-load live stream) so a later
// `initialize` can't desync the call/result of a tool card.
const terminalEnabled = terminalOutputCap
const record: SessionRecord = {
sessionId: params.sessionId, agent, presenter: makePresenter(), terminalEnabled, inflight: undefined,
}
sessions.set(params.sessionId, record)
// Replay the persisted event log to the client as session/update. Use
// the raw event log (NOT deriveMessages, which drops assistant/chunk
@@ -492,7 +509,7 @@ export function apply(ctx: Context, config: AcpConfig): void {
// so the record's presenter starts clean for the post-load live stream.
const replayPresenter = makePresenter()
const replayTerminal: TerminalRendering = {
enabled: terminalOutputCap,
enabled: terminalEnabled,
cwd: agent.session.header.cwd,
}
for (const event of agent.session.events) {

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@@ -159,6 +159,34 @@ describe('acp bridge — turn outcomes', () => {
expect(meta.terminal_exit).toEqual({ terminal_id: 'c1', exit_code: 0 })
})
it('the terminal capability is snapshotted per-session: a later initialize cannot desync a call/result', async () => {
// The session is created with the capability ON. A SECOND initialize then
// turns it OFF at the connection level — but this session keeps its snapshot,
// so its bash call STILL renders as a terminal card (call + result agree).
// Without the snapshot, the result path would re-read the now-OFF capability
// and either clobber the card (content sent) or be inconsistent with the call.
harness = await makeBridgeHarness({
storageDir,
withBash: true,
script: [toolCallResponse('c1', 'bash', { command: 'echo hi', description: 'Greet' }), textResponse('done')],
})
await harness.client.initialize({ protocolVersion: PROTOCOL_VERSION, clientCapabilities: { _meta: { terminal_output: true } } })
const { sessionId } = await harness.client.newSession({ cwd: process.cwd(), mcpServers: [] })
// A re-initialize that DROPS the capability after the session exists.
await harness.client.initialize({ protocolVersion: PROTOCOL_VERSION, clientCapabilities: {} })
await harness.client.prompt({ sessionId, prompt: [{ type: 'text', text: 'greet' }] })
const call = harness.updates.find(u => u.sessionUpdate === 'tool_call')
if (call?.sessionUpdate !== 'tool_call') throw new Error('expected a tool_call')
// Still a terminal card (the session's snapshot, not the mutated connection cap).
expect((call._meta as { terminal_info?: unknown }).terminal_info).toBeDefined()
const update = harness.updates.find(u => u.sessionUpdate === 'tool_call_update')
if (update?.sessionUpdate !== 'tool_call_update') throw new Error('expected a tool_call_update')
// The result AGREES with the call: terminal output present, content omitted.
expect(update.content).toBeUndefined()
expect((update._meta as { terminal_output?: unknown }).terminal_output).toBeDefined()
})
it('a throwing tool presenter does not break the turn: the bridge falls back generically', async () => {
// A buggy tool whose presentCall throws must not fail the live turn — the
// bridge's presenter contains the throw (logging via its onError sink) and

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@@ -34,7 +34,7 @@ The owning agent is recorded per task id at spawn and kept for the lifetime of t
## UI presentation
These tools own how their calls render in a UI (an editor's tool-call card) via the `dsh-tools` `presentCall`/`presentResult` seam — a UI never special-cases tool names. For `bash`: the **title** is the exact `command` ("ls -la src") and `kind` is `execute` (terminal/run treatment), matching the reference ACP adapters (claude-agent-acp, codex-acp), which both use the bare command as an execute tool's title. The command is ALSO the **rawInput** for non-terminal UIs that render it (an execute-kind card hides rawInput — Zed shows it only for non-terminal tools — so the command must BE the title to be seen). The model-written `description` rides as a **content** text block shown ABOVE the card (a terminal card has no description slot, so it sits over the command; claude-agent-acp likewise surfaces the description as a separate content block). The completed output is wrapped in a fenced ` ```console ` block as the no-terminal-capability fallback — a UI-only affordance, so the model-facing result text stays unfenced. `bash` also flags itself as a **terminal** (the neutral `terminal` field: `presentCall` sets a `cwd` from the model `workdir` when given — absolute as-is, relative for the UI bridge to resolve against the session cwd — else leaves it for the bridge to fill from the session cwd; `presentResult` carries the raw output plus the parsed `exitCode`/`signal`) so a capable client (Zed) renders a terminal card with an exit-status pill instead of the text block — see `packages/acp` ("Terminal card"). `bash_output`/`bash_kill` present a task-scoped title ("Read output from background task bash-3" / "Kill background task bash-3") with the task id as rawInput. These methods are pure/display-only (they also run on `session/load` replay), and a malformed/older logged arg shape falls back to a generic presentation rather than throwing. See `packages/tools` ("Tool-owned UI presentation") and `packages/acp` ("Terminal card" / "Tool-call presentation").
These tools own how their calls render in a UI (an editor's tool-call card) via the `dsh-tools` `presentCall`/`presentResult` seam — a UI never special-cases tool names. For `bash`: the **title** is the exact `command` ("ls -la src") and `kind` is `execute` (terminal/run treatment), matching the reference ACP adapters (claude-agent-acp, codex-acp), which both use the bare command as an execute tool's title. The command is ALSO the **rawInput** for non-terminal UIs that render it (an execute-kind card hides rawInput — Zed shows it only for non-terminal tools — so the command must BE the title to be seen). The model-written `description` rides as a **content** text block shown ABOVE the card. (claude-agent-acp DROPS the description in terminal mode and shows only the card; surfacing it as a content block is a deliberate divergence — we keep the human summary visible alongside the card.) The completed output is wrapped in a fenced ` ```console ` block as the no-terminal-capability fallback — a UI-only affordance, so the model-facing result text stays unfenced. A FOREGROUND `bash` run also flags itself as a **terminal** (the neutral `terminal` field: `presentCall` sets a `cwd` from the model `workdir` when given — absolute as-is, relative for the UI bridge to resolve against the session cwd — else leaves it for the bridge to fill from the session cwd; `presentResult` carries the raw output plus the parsed `exitCode`/`signal`) so a capable client (Zed) renders a terminal card with an exit-status pill instead of the text block — see `packages/acp` ("Terminal card"). A `run_in_background` call is NOT a terminal (it returns a task id immediately and never streams a terminal — poll with `bash_output`), and an `isError` result (spawn failure / abort) carries no exit pill (there is no real process exit); both render as the ordinary execute card / fenced text. `bash_output`/`bash_kill` present a task-scoped title ("Read output from background task bash-3" / "Kill background task bash-3") with the task id as rawInput. These methods are pure/display-only (they also run on `session/load` replay), and a malformed/older logged arg shape falls back to a generic presentation rather than throwing. See `packages/tools` ("Tool-owned UI presentation") and `packages/acp` ("Terminal card" / "Tool-call presentation").
## Background completion notices

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@@ -139,23 +139,32 @@ export function renderResult(result: BashRunResult): string {
* mirrors the reference ACP adapters (claude-agent-acp, codex-acp), which both
* use the bare command as an execute tool's title. The model-written
* `description` (a readable summary) rides as a `content` text block shown ABOVE
* the card, since a terminal card has no description slot — claude-agent-acp
* likewise surfaces its description as a separate content block. `rawInput` still
* carries the bare command for non-execute UIs that DO render it.
* the card. (Note: claude-agent-acp DROPS the description in terminal mode and
* shows only the card; surfacing it as a content block is a deliberate
* divergence here — we keep the human summary visible alongside the card.)
* `rawInput` still carries the bare command for non-execute UIs that DO render it.
*
* `terminal` marks the call so a capable UI renders a TERMINAL card. Its `cwd`
* (header) is the model `workdir` when given — ABSOLUTE as-is, RELATIVE for the
* UI bridge to resolve against the session cwd; when omitted entirely the bridge
* fills the session workspace cwd (this PURE presenter, args only, can't see it).
* `terminal` marks the call so a capable UI renders a TERMINAL card — but ONLY a
* FOREGROUND run is a terminal: a `run_in_background` call returns a task id
* immediately (it never streams a terminal; its output is polled via
* `bash_output`), so it is NOT marked terminal and renders as an ordinary
* execute card. For a foreground run the `terminal.cwd` (header) is the model
* `workdir` when given — ABSOLUTE as-is, RELATIVE for the UI bridge to resolve
* against the session cwd; when omitted the bridge fills the session workspace
* cwd (this PURE presenter, args only, can't see it).
*/
function presentBashCall(args: { command: string; description: string; workdir?: string }): ToolCallPresentation {
return {
type BashCallArgs = { command: string; description: string; workdir?: string; run_in_background?: boolean }
function presentBashCall(args: BashCallArgs): ToolCallPresentation {
const base = {
title: args.command,
kind: 'execute',
kind: 'execute' as const,
rawInput: args.command,
content: [{ type: 'text', text: args.description }],
terminal: args.workdir !== undefined ? { cwd: args.workdir } : {},
content: [{ type: 'text' as const, text: args.description }],
}
// A background start is not an interactive terminal — no terminal card.
if (args.run_in_background === true) return base
return { ...base, terminal: args.workdir !== undefined ? { cwd: args.workdir } : {} }
}
/**
@@ -167,37 +176,58 @@ function presentBashCall(args: { command: string; description: string; workdir?:
* support (the fences are a UI-only affordance, so they live here, not in the
* model-facing result; the fenced body is trimmed of trailing blank lines for a
* tidy block). A capable UI also gets an exit-status pill from `terminal.exitCode`
* / `terminal.signal`, parsed from the status markers `renderResult` appended
* (this parse is the exact inverse of those markers — they co-evolve in this
* file and a round-trip test guards the pair). A non-text result (unexpected for
* bash) falls through to `undefined` (UI keeps the raw result).
* / `terminal.signal`, parsed from the status markers `renderResult` appended.
*
* Terminal output/exit is suppressed for results that are NOT a finished
* foreground run: a `run_in_background` start (`isBackground` — the text is a
* task-id ack, not a streamed run) and an `isError` result (a spawn failure or
* abort — there is no real process exit to pill, and the body is an error
* message, not `renderResult` output, so parsing it would be meaningless). Those
* fall back to the fenced `content` block with no terminal metadata. The bridge's
* orphan guard also drops a result terminal when the call wasn't terminal, so a
* background call (not marked terminal in `presentBashCall`) is doubly safe.
* A non-text result (unexpected for bash) falls through to `undefined`.
*/
function presentBashResult(_args: unknown, result: ToolResult): ToolResultPresentation | undefined {
function presentBashResult(args: unknown, result: ToolResult): ToolResultPresentation | undefined {
const block = result.content.length === 1 ? result.content[0] : undefined
if (block === undefined || block.type !== 'text') return undefined
const raw = block.text
const fenced = raw.replace(/\n+$/, '')
return {
content: [{ type: 'text', text: `\`\`\`console\n${fenced}\n\`\`\`` }],
terminal: { output: raw, ...parseExitStatus(raw) },
}
const content = [{ type: 'text' as const, text: `\`\`\`console\n${fenced}\n\`\`\`` }]
const isBackground = typeof args === 'object' && args !== null && (args as { run_in_background?: unknown }).run_in_background === true
// No exit pill / terminal output for a background ack or an errored run.
if (isBackground || result.isError) return { content }
return { content, terminal: { output: raw, ...parseExitStatus(raw) } }
}
/**
* Recover the structured exit status from a rendered `renderResult` string — the
* inverse of the status markers it appends. A `[killed by signal: SIG]` marker
* yields `{signal}`; otherwise an `[exit code: N]` marker yields `{exitCode:N}`;
* a clean run appends neither, so absent both we report `{exitCode:0}`. (A
* trapped-timeout run that exits 0 has no signal/exit marker either and reads as
* exitCode 0, which is accurate — it did exit 0.) `renderResult` always appends
* the exit/signal marker LAST (after any timeout marker) onto a non-empty body,
* so the marker is anchored at end-of-string here — output that merely CONTAINS
* such text earlier is not mistaken for it.
* absent both we report `{exitCode:0}` (a clean run appends no marker — and a
* trapped-timeout run that exits 0 also has none and is accurately exit 0).
*
* Why parse rendered text at all: `presentResult` is replay-safe and on a
* `session/load` the ONLY thing persisted is this content text — the structured
* `BashRunResult` is long gone — so unless the exit were added to the persisted
* event schema (deliberately NOT done; see the terminal-rendering RFC), parsing
* is the only channel. The match is anchored to a LEADING newline + end-of-string
* because `renderResult` always inserts a `\n` before the marker (line ~124) onto
* a non-empty body: a real marker is therefore always its own final line. That
* defeats the common spoof (program output that simply ENDS in `[exit code: 5]`
* with no trailing newline — a clean exit 0 — no longer reads as a failure).
*
* KNOWN RESIDUAL (inherent to the replay-only-sees-text design): a clean exit 0
* whose body's FINAL line is itself exactly `\n[exit code: N]` (the program
* printed that line and nothing after) is still indistinguishable from a real
* marker and would show a wrong pill. This is display-only (execution and the
* model-facing text are unaffected) and narrow; the complete fix is to persist a
* structured exit on the result event, which the RFC names as the escape hatch.
*/
function parseExitStatus(text: string): { exitCode: number } | { signal: string } {
const signal = /\[killed by signal: ([^\]\n]+)\]$/.exec(text)
const signal = /\n\[killed by signal: ([^\]\n]+)\]$/.exec(text)
if (signal?.[1] !== undefined) return { signal: signal[1] }
const exit = /\[exit code: (\d+)\]$/.exec(text)
const exit = /\n\[exit code: (\d+)\]$/.exec(text)
if (exit?.[1] !== undefined) return { exitCode: Number(exit[1]) }
return { exitCode: 0 }
}

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@@ -632,6 +632,48 @@ describe('tool-owned UI presentation (presentCall / presentResult)', () => {
}
})
it('bash presentResult: a clean exit-0 whose output ENDS in marker-like text is NOT read as a failure', async () => {
const ctx = await setup()
const args = { command: 'printf "[exit code: 5]"', description: 'print' }
// A successful command can print text that looks like a marker. renderResult
// for a clean exit 0 appends NOTHING (and no trailing newline), so the body's
// own tail is `[exit code: 5]`. The parse requires a LEADING newline before
// the marker (renderResult always inserts one before a REAL marker), so this
// no-trailing-newline body is NOT mistaken for a failure → exitCode 0.
const out = ctx.tools.get('bash')!.presentResult!(args, { content: [{ type: 'text', text: '[exit code: 5]' }], isError: false })
expect(out?.terminal).toEqual({ output: '[exit code: 5]', exitCode: 0 })
// Same for a fake signal marker with no leading newline.
const sig = ctx.tools.get('bash')!.presentResult!(args, { content: [{ type: 'text', text: '[killed by signal: SIGKILL]' }], isError: false })
expect(sig?.terminal).toEqual({ output: '[killed by signal: SIGKILL]', exitCode: 0 })
})
it('bash presentCall/presentResult: a run_in_background call is NOT a terminal and its ack carries no exit pill', async () => {
const ctx = await setup()
// The background start returns a task-id ack, not a streamed run — no terminal.
const call = ctx.tools.get('bash')!.presentCall!({ command: 'sleep 100', description: 'wait', run_in_background: true })
expect(call).toEqual({ title: 'sleep 100', kind: 'execute', rawInput: 'sleep 100', content: [{ type: 'text', text: 'wait' }] })
expect((call as { terminal?: unknown }).terminal).toBeUndefined()
// The ack result is fenced text only — no terminal output / exit pill.
const result = ctx.tools.get('bash')!.presentResult!(
{ command: 'sleep 100', description: 'wait', run_in_background: true },
{ content: [{ type: 'text', text: 'started background task bash-1' }], isError: false },
)
expect(result?.terminal).toBeUndefined()
expect(result?.content).toEqual([{ type: 'text', text: '```console\nstarted background task bash-1\n```' }])
})
it('bash presentResult: an isError result carries no exit pill (no real process exit to report)', async () => {
const ctx = await setup()
// A spawn failure / abort has no process exit — the body is an error message,
// not renderResult output, so no terminal output/exit is emitted.
const out = ctx.tools.get('bash')!.presentResult!(
{ command: 'x', description: 'x' },
{ content: [{ type: 'text', text: 'command aborted' }], isError: true },
)
expect(out?.terminal).toBeUndefined()
expect(out?.content).toEqual([{ type: 'text', text: '```console\ncommand aborted\n```' }])
})
it('bash presentResult: leaves a non-text (unexpected) result untouched → undefined (UI keeps raw content)', async () => {
const ctx = await setup()
const present = ctx.tools.get('bash')!.presentResult!(