Resource-oriented ACP comparison

Traceability

• Spec ID: studio-acp-resource-compare
• Status: Implemented

Intent

Make a completed or running ACP comparison explain which project resources each AI inspected, changed, or verified. Keep the simple project-and-Prompt entry surface, but replace manual cross-reading of two transcripts with one resource-oriented comparison that retains the originating tool calls and their recorded results.

Acceptance Scenarios

• AC-1: A canonical ACP tool call with multiple parsed_cmd entries projects into multiple observable operations without pretending that each operation was a separate provider call.
• AC-2: Reads, searches, edits, listings, verification commands, and generic commands are associated with normalized resource keys when the recorded input or result supplies one; trial-root absolute paths are not rendered in the UI.
• AC-3: Compare can show one row per resource with Baseline and Candidate operations aligned around that shared resource, including run-only resources and multiple operations from one call.
• AC-4: Selecting an operation exposes its recorded status and a bounded, browser-safe result summary while preserving access to the two original message streams.
• AC-5: The resource comparison updates from canonical tool-start and tool-result events during a live run and does not infer unobserved reads, edits, tests, or intent.
• AC-6: The resource view has visible keyboard focus, labelled controls, no document-level horizontal overflow, and a usable bounded horizontal layout at 1440x900, 1024x768, and 390x844.

Non-goals

• Build a free-form node graph, infer causal intent, or rank a model from a single matched trial.
• Add a new ACP provider payload to the browser contract.
• Replace patch receipts or grader results with tool-call claims.
• Implement an arbitrary repository file browser or editor.

Plan and Tasks

• Add an operation projection beside the existing single-call normalization. Extract nested parsed_cmd operations, recorded changes, and narrow result-derived diff paths while retaining call identity.
• Reuse that projection in the existing resource ledger so Advanced evidence no longer reports zero resources for composite ACP calls.
• Add a default Resource map and a Messages switch to the simple Compare result area. Use docked rows and a bounded operation-result inspector rather than cards or a free-form graph.
• Add focused model and component/browser coverage, then verify the live page at the three Studio layout widths.

Test and Review Evidence

• AC-1/AC-2: model tests cover a compound list/search/read call, an absolute edit path, a diff/status verification call, and result summarization.
• AC-3/AC-4: component/browser tests assert shared resource rows, lane-only operations, the Messages fallback, and an accessible operation inspector.
• AC-5: stream-fold tests prove a running call becomes a completed operation with the recorded result without changing call identity.
• AC-6: Playwright screenshots and console/page-error inspection at 1440x900, 1024x768, and 390x844.
• Risk: treating command output as fact can create false reads. Result parsing is limited to changed-file/diff evidence and never promotes arbitrary stdout paths to reads.
• Risk: compound calls make raw call counts misleading. The UI labels operation rows with their parent call sequence instead of comparing operation count as a quality score.

Observed locally on 2026-08-26 with Node 24.15.0: Harness tests passed 172/172, Studio tests passed 283/283, and the focused Compare browser checks passed 2/2. The real codex-acp comparison projected five resources, four shared resources, one edited resource, and a Candidate-only README verification without exposing the temporary worktree path. Wide, compact, and narrow screenshots had no document-level horizontal overflow or browser console/page errors.