Collapse the Sessions workbench chrome and restore Session discovery in the desktop shell

Traceability

• Spec ID: studio-sessions-workbench-chrome
• Status: Implemented

Intent

The Sessions View in the desktop shell stacks three headers before any evidence appears, and the evidence itself is empty. A reader opening Harness Studio on a Project with a hundred retained Sessions sees 0 sessions, three bands of chrome that each restate "Harness Inspector", and two fixed-width columns that cannot be resized.

Two separate defects produce that screen:

1. Duplicated chrome. The window toolbar already names the View (Sessions). Below it, session-workbench-toolbar opens a second bar with Session evidence / Inspector-owned Project observations and the Inspector / Catalog surface switcher. Inside the embedded Inspector, a third block names Harness Inspector over the Project name, and a fourth restates Harness Inspector / as a breadcrumb prefix. DESIGN.md already forbids this: "Show a surface switcher once per viewport", "Do not duplicate navigation or status merely to fill a header".
2. No Sessions. The desktop shell discovers Sessions through the bundled dist/server/runtime/inspector-workspace-runtime.mjs, produced by esbuild from packages/harness-studio/scripts/inspector-workspace-provider.mjs. scripts/session-analysis/analyzer.mjs loads each host adapter with await import(entry.specifier), where entry.specifier is a variable. esbuild cannot follow a computed specifier, so it leaves the expression in the output; at runtime it resolves ./platforms/<host>.mjs relative to the bundle, where no platforms/ directory exists. Every one of the thirteen providers fails with Cannot find module …, the provider runner records status: "error", and discovery returns zero Sessions.

The failure is silent to the reader: the per-provider error messages never reach the UI, and the Sessions surface reports the generic Nothing in this window. Widen the date range in the sidebar. — which blames the date range for a module-resolution defect.

Measured evidence

Both providers run against the same directory, on the same host:

entry point	providers ok	discovered	report Sessions
packages/harness-studio/scripts/inspector-workspace-provider.mjs (source)	5	118	100
packages/harness-studio/dist/server/runtime/inspector-workspace-runtime.mjs (bundled)	0	0	0

report.days is 5 in both runs, because Git history is collected through statically-resolved imports. Only the dynamically-loaded host adapters break, which is why the workbench renders a populated date navigator with no Sessions behind it.

Acceptance scenarios

• AC-1 Given the bundled workspace runtime and a Project directory with retained local Sessions, when discovery runs, then it returns the same provider statuses and Session count as the repository-local provider module, and no provider reports a module-resolution error.
• AC-2 Given the Sessions View with the Inspector workbench available, when it renders, then exactly one bar above the evidence names the View, and the Inspector / Catalog surface switcher lives in that bar.
• AC-3 Given the embedded Inspector workbench, when it renders, then no region restates the product name Harness Inspector, and the scope picker carries no brand block above its mode tabs.
• AC-4 Given the Sessions View at wide and compact widths, when the reader drags the divider between the scope picker and the workbench, then the picker resizes within its bounds, the size survives a re-render, Home/End and the arrow keys move it from the keyboard, and double-click restores the default.
• AC-5 AC-4 also holds for the divider between the Session catalog pane and the Session detail pane on the Catalog surface.
• AC-6 Given the narrow layout (390px), when the Sessions View renders, then the panes stack, the sashes are inert, and the document has no horizontal overflow.

Non-goals

• Re-designing the Inspector workbench card lanes, metrics strip, or Session View overlay.
• Changing the standalone harness-inspector HTML report chrome. That report opens offline with no shell around it, so its own brand block and breadcrumb are the only thing naming it; test/reporting/harness-inspector.test.mjs pins that contract and stays unchanged.
• Adding a per-provider discovery diagnostics surface. The provider statuses are already carried in StudioWorkspace.providers; exposing them is separate work.
• Changing which hosts are supported, or how any single adapter parses evidence.

Plan

1. Host adapter loading. Replace the computed specifier string in scripts/session-analysis/analyzer.mjs with a per-host load() thunk that contains a literal import("./platforms/<host>.mjs"). A bundler can follow a literal specifier inside a thunk, so the adapters are inlined into the workspace runtime while direct source consumers keep lazy loading.
2. One bar. Delete session-workbench-toolbar and the session-workbench-stack wrapper from SessionsWorkspace. Render the surface tablist through ToolbarActions into the window toolbar's action slot, the same route GitHistoryView already uses. Retire the now-unused sessions.workbenchTitle and sessions.workbenchDetail strings.
3. Inspector chrome. In InspectorWorkbench, drop the .brand block and move the picker collapse control onto the mode-tab row; drop the Harness Inspector / breadcrumb prefix, and omit the breadcrumb entirely when the shell's date range is in force and the picker is in Sessions mode, because the toolbar and sidebar already state that scope.
4. Resizable panes. Give the embedded Inspector a PaneSash between the scope picker and the workbench, and the Session catalog a PaneSash between the list and the detail pane. Bounds come from a measured ResizeObserver frame, as in GitHistoryView, so a dragged size cannot survive a window that no longer has room for it. The Inspector sash lives inside the shadow root, so its styles ship in the embedded stylesheet rather than in shell.css.

Test and review evidence

• packages/harness-studio/test/inspector-workspace-provider.test.mjs — extended with a case that bundles the host-adapter registry the way the shipped runtime does and loads every supported adapter through it (AC-1). The regression is a resolution failure, so the test asserts on the loaded module, not on source text. Confirmed non-vacuous: the same bundle built from the pre-fix registry fails with Cannot find module …/platforms/codex.mjs.
• npx vitest run in packages/harness-studio — 78 files, 592 tests pass.
• npx vitest run test/reporting/harness-inspector.test.mjs — 39 tests pass, proving the standalone report's brand block and breadcrumb are unchanged.
• npx vitest run test/sessions — 25 files, 449 tests pass, covering the session-analysis registry and the commit-session correlation that reads it.
• npx vitest run test/skills-docs/doc-link-graph.test.mjs — 8 tests pass.
• Playwright against the built app served with shell=desktop&controls=left, on this repository as the open Project:

observation	before	after
bars above the evidence	2	1 (studio-context-bar)
.brand blocks in the embedded Inspector	1	0
elements reading exactly Harness Inspector	2	0
Session rows / workbench cards	0 / 0	100 / 100
workbench header badge	all · 0 sessions	4 providers
status bar	100 sessions twice	once
picker sash aria-valuenow	absent	270 → 390 (drag) → 374 (ArrowLeft ×2) → 270 (double-click)
catalog sash aria-valuenow	absent	300 → 447 (drag)
picker sash height vs pane height	54 049px vs 820px	820px vs 820px
document horizontal overflow at 1440 / 1024 / 390	—	none
sashes at 390px	—	tabindex=-1, display:none
browser console and page errors	—	none

Screenshots for each surface and width are in .tmp/sessions-review/ (wide-inspector.png, wide-inspector-resized.png, wide-catalog.png, compact-inspector.png, narrow-inspector.png, narrow-catalog.png).

Follow-ups found while verifying, not addressed here

• restoreActiveProject fails silently for a remembered Project whose id does not match projectForId's project_<32 hex> pattern, and restoreRememberedProjects swallows the result. A launch then opens on the gate with no diagnostic. Reproduced only with a hand-seeded catalog, so it is not the reported defect, but the silent path is worth a look.
• Per-provider discovery statuses already reach StudioWorkspace.providers and are never surfaced. Had they been visible, the thirteen Cannot find module … errors behind this spec would have been legible in the UI instead of reading as an empty date window.