Make session review and harness comparison read like a notebook

Traceability

• Spec ID: notebook-session-and-studio
• Status: In Progress

Intent

Make a retained Session and a live Harness Studio comparison easier to scan by using the same notebook-shaped mental model: shared context first, then one understandable work unit with its input, collapsible process, result, and evidence. The two products keep their existing authority boundaries. Inspector remains a read-only presentation of retained evidence, while Studio may lock and run an already supported checkpoint-backed comparison.

The supplied Jupyter-style reference defines hierarchy, composition, and rhythm, not a new data contract. The implementation should visibly read as a notebook at first glance: one application bar, one wide cell stream, a continuous In/Out execution rail, and a narrow contextual rail. Labels and actions must continue to describe facts the product actually owns.

Acceptance Scenarios

• AC-1: Inspector Session Detail renders every retained Turn as a numbered Run Cell with a visible input prompt, a collapsible Process section, and a result area. Each Process contains a timeline scoped to that Turn's retained calls, and one collapsed-by-default overall Session timeline appears before the first Turn so long Sessions retain an immediately discoverable global overview. Retained responses, commits, tool calls, and unplaced evidence keep their existing selection descriptors and evidence limitations.
• AC-2: Inspector does not label a Turn as a checkpoint, resumable state, code rollback, or successful artifact unless that fact already exists in the report. Trace/Replay, activity zoom, Jump, filters, call expansion, evidence selection, deep links, and the Continuation packet remain available.
• AC-3: Harness Studio Workbench presents one shared Context block, one Run Comparison cell, and one Compare Result cell. The Run cell owns the existing Run/Cancel action and Reference/Baseline/Candidate outputs; the Compare cell owns comparability plus Summary, Trace, and Evidence. Switching views or run roles keeps the existing data and selection state.
• AC-4: Studio continues to state one shared starting checkpoint and one derived treatment boundary without inventing duration, token, cost, authorship, correctness, or causality. Inspector and Studio both keep uncertainty and privacy-filtered content explicit.
• AC-5: At 1024 by 576, the Studio context and Run cell lead-in are visible, the focused call rows remain at least 11 px, and the document does not scroll horizontally. At 390 px, overflow stays inside the comparison surface and the context rail remains collapsible. Inspector Session Detail keeps one page scroller and stacks its index below the cells at narrow width.
• AC-6: Focused tests assert the rendered notebook structure and preserved interactions through DOM roles and behavior. Browser verification uses real report/experiment fixtures, exercises primary controls, checks console and page errors, and compares screenshots against the supplied reference at the same desktop viewport.
• AC-7: At desktop width, Studio uses a top Notebook bar, a wide left cell stream, and a right Checkpoints rail rather than a permanent left setup rail. Inspector uses the same main-stream/right-context composition but names the right rail Session outline and does not expose Continue, Fork, or checkpoint mutations. Generic card shadows, all-caps microcopy, and console-like gray framing do not dominate the above-the-fold notebook surface.
• AC-8: Inspector does not repeat a Session-level Context card above the Cell stream. Stable Session metadata stays in the notebook bar and outline; Turn activity stays inside its Process, and overall activity appears once before the first Cell as a collapsed disclosure.
• AC-9: Inspector preserves the observed order of intermediate assistant messages and tool calls through session parsing, report projection, Trace, and Replay. Presentation may collapse only adjacent tool-call runs. Counts distinguish intermediate responses, tool calls, and retained process events.
• AC-10: A terminal assistant response is retained as Out only when it is the final observed event in its Turn. A later tool call makes the retained Turn incomplete. The Outcome labels observed edit paths, verification calls, and correlated commits as evidence; it shows a code diff only from a retained, session-scoped patch artifact and never from the current worktree.
• AC-11: Intermediate and terminal assistant prose renders as sanitized Markdown without allowing raw HTML or executable links. At narrow widths, Trace/Replay, Continuation packet, Jump, filters, and Process controls remain reachable without horizontal document overflow.

Non-goals

• Adding a new checkpoint store, checkpoint mutation, native-session resume, replay execution, artifact adoption, or Git rollback.
• Merging Inspector and Harness Studio data models or moving Studio execution controls into the read-only Inspector.
• Replacing the existing Evidence Drawer, Studio comparison models, Builder, or server endpoints.
• Reproducing the reference image's branch picker, sharing controls, model names, test counts, file counts, or other illustrative facts when local evidence does not provide them.

Plan and Tasks

1. Restructure Inspector's existing Session Detail markup into Run Cell regions while preserving element ids, selection attributes, filters, tool disclosures, and Replay ownership. Keep Session-wide metadata in the title bar and outline rather than repeating a Context card.
2. Add notebook-specific Inspector styles for cell numbering, input/process/ result hierarchy, compact metadata, and responsive stacking.
3. Restructure Studio Workbench markup into a top Notebook bar, shared Context, Run Comparison and Compare Result cells, plus a right Checkpoints rail, without changing run, selection, or comparison models.
4. Extend Studio styles and browser coverage for the notebook hierarchy, desktop density, narrow containment, role switching, filtering, view tabs, and Run/Cancel behavior.
5. Restructure Inspector Session Detail into the same main-stream/right-outline composition while keeping its outline and evidence controls strictly read-only.
6. Render both products, capture desktop and narrow evidence, compare the implementation with the reference, fix actionable visual gaps, and run the focused and repository-level gates proportional to the changed surface.
7. Preserve one ordered Turn event stream in the session projection, expose response availability and honest event counts, and render the same order in Trace and Replay.
8. Replace the undifferentiated result prose with an evidence-bounded Outcome, add safe Markdown rendering, and keep notebook navigation available on narrow screens as specified by ADR-0006.
9. Keep the overall Session activity disclosure before the first Turn and collapsed by default in both standalone Inspector and Studio Session Detail.

Test and Review Evidence

• AC-1/AC-8 follow-up: standalone Inspector and Studio now render the overall Session activity disclosure before the first Turn and keep it closed on initial render. npx vitest run test/reporting/harness-inspector.test.mjs passed 39 tests; npm run harness-studio:test passed 65 files / 512 tests; the Studio browser suite passed 56 tests; and npm run inspector:visual-check passed all Trace, Usage, and Replay states at 1440 by 900, 1024 by 768, and 390 by 844 with no overflow or browser errors.
• AC-1/AC-2/AC-8: npx vitest run test/reporting/harness-inspector.test.mjs passed 28 tests. A real five-Turn, 230-call report rendered five scoped Process timelines and one overall Session timeline. The in-app browser exercised Process expansion, Trace, evidence selection/closure, and the read-only Session outline with no page or console errors. The rendered Session contains no Notebook Context card.
• AC-3/AC-4: npm run harness-studio:test passed 59 tests after rebuilding the package. The built Studio fixture exercised Builder -> Workbench, Process, Run, Summary/Trace/Evidence, call filtering, and synchronized selection in the in-app browser with no console or page errors.
• AC-5/AC-7: browser measurements covered 1229 by 819 and 1024 by 576 desktop states plus two 390 by 844 narrow iframes. Each iframe's one-pixel border leaves a 388 px inner viewport: Studio document and workspace widths stayed 388 px, the Checkpoints rail was hidden by default and reopened as a 335 px overlay without document overflow. Inspector document, Session View, and layout widths stayed 388 px; the first Cell started at 70 px and the stacked Session outline began after the Cell stream. Five Process disclosures and one overall activity section were present.
• AC-6: the prior same-scale reference/implementation boards and desktop/narrow captures were recorded in the local ignored design-qa.md; they are not used as review evidence for AC-9 through AC-11. The Studio browser test covers the notebook region, Context, two Cell regions, Process disclosure, desktop dimensions, collapsed narrow rail, and the 335 px Checkpoints overlay; node --check passed for that test file and the same interactions were exercised in the in-app browser. git diff --check, node --check for the updated Playwright test, documentation link graph (6 tests), full root suite (95 files / 1327 tests), package verification (541 npm / 563 runtime-zip entries), and preview /health plus /canvas-module.js smokes all passed.
• AC-9/AC-10: npx vitest run test/sessions/commit-session-link.test.mjs test/reporting/harness-inspector.test.mjs passed 70 tests. The parser test asserts tool -> intermediate -> tool, an incomplete terminal status, and separate observed/retained counts; the report-model test asserts that the same order and response status cross the Inspector projection unchanged. The real 96-event Turn rendered alternating Intermediate/tool-run regions, reported 80 of 96 process events retained, aligned Out with the Outcome, and labeled its edit path while explicitly declining to derive a patch from the current worktree.
• AC-11: browser verification at 1280 by 720 and 390 by 844 kept Trace, Replay, Continuation packet, Jump, filters, and Process controls visible with document widths equal to viewport widths. Rendered assistant Markdown contained real heading and list elements, no raw script or iframe nodes, and Process expansion preserved the observed event order. Replay opened at event 1 of 139; expand/collapse worked for all six Turns; browser warnings and errors were empty. npm run harness-studio:test passed 59 tests, the documentation link graph passed 6 tests, the full root suite passed 95 files / 1327 tests, node --check, git diff --check, and preview /health plus /canvas-module.js smokes passed.
• Risk: notebook terminology can overstate state continuity. UI copy uses Turn, Run, result, and evidence, and reserves checkpoint for the one Studio checkpoint source that the server already verifies.
• Risk: added hierarchy can consume too much vertical space. Context stays compact, Process stays collapsed by default, and repeated metadata is owned once per notebook or cell.
• Remaining activation decision: the ADR is still Proposed, so this spec remains In Progress until maintainers accept the ordered-event and session-scoped patch boundary or request a different report contract.