Simplify Sessions navigation and evidence views

Traceability

• Spec ID: sessions-ui-refinement
• Status: Implemented
• Request: user supplied seven Sessions UI corrections and a screenshot.

Intent

Prioritize session evidence and interactive charts inside the docked Studio.

Acceptance Scenarios

• AC-1: No Inspector boundaries banner; scoped counts appear in a bottom status row.
• AC-2: Both evidence lane separators resize with pointer and keyboard and reset on double-click; narrow layouts stack without overflow.
• AC-3: Expanded actions expose an interactive graph with selection, zoom and call details instead of a flat list.
• AC-4: Unassigned records remain accessible in a collapsed, plainly named section without implying a turn association.
• AC-5: Session back is at the left, redundant branding is absent, and return preserves scope and focus.
• AC-6: Usage report shows charts and their necessary labels/controls, without introductory dashboards and accounting prose.
• AC-7: Workspace Sessions has no Catalog & Compare switcher; existing standalone Compare is outside scope.

Non-goals

No data collection, billing semantics, native installation, release metadata, or standalone report rewrite. Preserve the fallback catalog for hosts without workspace inspection.

Plan and Tasks

Update React Inspector, shared lane sash integration, Sessions routing and English/Chinese labels. Use existing semantic tokens. Graph uses observed timestamps when all calls have them, otherwise explicitly labelled call order; no invented timing. Add focused browser interaction coverage.

Test and Review Evidence

• AC-1/AC-7: browser confirms the banner and Catalog & Compare tab are absent and scope metrics are in the footer. The fallback catalog and standalone comparison remain covered.
• AC-2: browser measures both lane widths after arrow-key input, pointer dragging and double-click reset.
• AC-3: browser selects graph points and uses arrow keys; a 287-call untimed fixture proves 60-call bounded rendering, paging and zoom. Real project inspection also showed 60 visible marks for a 152-call session with no graph overflow.
• AC-4/AC-5: browser verifies the other-records disclosure, left-positioned back button, history exit and restored trigger focus; Session view is a navigable region rather than an aria-modal dialog.
• AC-6: duplicate report summary, methodology, accounting and response-detail panels are removed; existing usage graph hover, click and keyboard checks pass.
• npm run build --workspace packages/harness-studio and npm run typecheck --workspace packages/harness-studio: passed.
• From Studio: npx vitest run test/inspector-session-model.test.ts test/design-tokens.test.ts: 23 tests passed.
• From Studio: npx playwright test test/browser/artifact-host.spec.mjs -g 'opens a project workspace': passed, including wide/compact/narrow screenshots, dark/reduced-motion graph and console/page error collection.
• npm run preview: /health and /canvas-module.js both returned 200.
• npx vitest run test/skills-docs/doc-link-graph.test.mjs: 8 tests passed; routing graph regenerated without changes.
• Visual evidence: Studio test-results includes session-actions-long-wide/compact/narrow/dark, session-detail-trace, session-detail-usage and session-inspector screenshots. A real-project screenshot is retained in Studio test/.artifacts/sessions-ui/real-project-wide.png.

Review Readiness

The seven changed files (including the new graph and this spec) map to the acceptance scenarios above. No issue id was supplied; the explicit user request is the task evidence. AI implementation: Codex. No staged changes, commits, dependency changes or generated release artifacts are included. Other tasks' concurrent edits were left alone.

Risks and limits: browser/source evidence only, not an installed desktop build or Windows/Linux native validation. The new React graph supports selection and bounded window zoom; it does not claim every standalone chart overlay has been ported. Missing timing uses explicit call order. Standalone Inspector remains unchanged.