Simplify the Debugger workbench

Traceability

• Spec ID: debugger-unified-chrome
• Status: Implemented

Intent

Merge Debugger commands and run status into Studio's existing window chrome, reduce repeated explanation, and make the first request reach an honest terminal state.

Acceptance Scenarios

• AC-1: Debugger commands appear in the single Studio title bar; saved runs and pane toggles remain keyboard reachable.
• AC-2: One bottom status region carries run status, event count, and a compact timeline; no empty timeline band.
• AC-3: Prompt and activity lead the live workspace; runtime metadata remains available in the inspector without repeated status paragraphs.
• AC-6: Available ACP Agents are selected by default through the existing ACP route; explicit SDK choice remains supported. Qoder streamed prompts use text content blocks.
• AC-4: Failed or prematurely closed streams leave the running state and display the error; pending event batches cannot overwrite that failure.
• AC-5: Wide, compact, and narrow layouts have bounded overflow and no browser errors.

Non-goals

New hosts, publishing, installation, and changes to unrelated Studio views.

Plan and Tasks

Reuse the shell toolbar portal and add a status slot. Simplify live chrome and keep recorded navigation available. Inspect local failure evidence and test the stream lifecycle at its public boundary. Validate built browser flows and screenshots.

Test and Review Evidence

• AC-4/6: Harness adapter and executor tests: 38 passed; Studio run store, stream lifecycle, and Agent selection tests: 15 passed.
• AC-6: Existing Rust ACP native route test: 1 passed, including permission response.
• AC-1/2/3/5: Built Playwright flows cover default/explicit ACP selection, wide/compact/narrow layouts, dark appearance, keyboard focus, project binding, failed tool payload disclosure, and saved-run replay.
• Studio and Harness builds passed. Doc link graph: 8 passed. Canvas preview health and module endpoints both returned 200.
• Review Readiness: no Story supplied; this is user-requested maintenance. No staged changes, release metadata, or generated-code changes belong to this task. Concurrent Overview removal edits are outside this spec; shared App/test hunks were preserved. Risks: toolbar width and late stream callbacks are covered above.
• Native ACP verification used the existing Rust binary with a fixture Agent. The user's running Electron window and authenticated real Agent were not relaunched or measured; no installed-host completion claim is made. AI involvement: Codex implementation and local verification.

Failure evidence

The screenshot run run_1788782230814_r6y6ff retained API Error: A.message.content.map is not a function. The installed SDK documents streamed user messages with text content blocks; the adapter supplied a string. Desktop currently supplies a Rust ACP host executable; NSXPC is wired to OXC. No new ACP transport is introduced.