Browse and compare local sessions in Harness Studio

Traceability

• Spec ID: harness-studio-local-web-workspace
• Status: Implemented

Intent

Harness Studio is a local Web application, not a collection of views enabled by startup flags. Launching the server should open an empty workbench. The user then chooses a project working directory in the Web UI. Studio passes that absolute local workspace identity to the same in-process discovery capability used by Harness Inspector, which finds workspace-matching sessions in each supported host's evidence store. The user does not need to know where a host stores transcripts or select a Session directory manually.

The product hierarchy is Workspace -> Sessions -> Session detail / Compare -> Session artifacts. CLI arguments may preload data for compatibility and automation, but they do not own the interactive workflow or determine whether a surface exists.

Decisions

• D-1: the project workspace is the root aggregate. A selected local working directory creates one replaceable workspace scope. Session, compare, and artifact routes resolve through the sessions discovered for that scope.
• D-2: a local server owns directory selection. A normal browser directory input cannot reveal a portable absolute path, so it cannot establish the same workspace identity as Inspector. A same-origin POST asks the loopback server to open the operating system's directory chooser. No project files are uploaded or copied into Studio.
• D-3: reuse Inspector discovery code in process. Studio calls the existing multi-provider session-analysis capability with the selected workspace. It does not invoke an Inspector or session-analysis CLI subprocess and does not duplicate host path/slug rules in React.
• D-4: Session Compare is observational. Comparing two selected sessions shows retained status, duration boundary, tool calls, messages, and semantic phase differences. It does not emit a winner or reuse the frozen harness-compare verdict contract without evaluation evidence.
• D-5: artifacts are session-scoped. Artifact View is reached from the current session and resolves only that session's artifact set. A loose artifact directory is a compatibility preload, not the primary information architecture.
• D-6: better-harness web is a launcher only. The future public command locates and starts the packaged Studio application. Selecting or switching a workspace remains entirely inside the Web UI.
• D-7: slow discovery reports real stages, not fake percentages. While an open request is pending, Studio exposes only the coarse server-owned stage: waiting for the native directory chooser or discovering workspace-matched Sessions. The Web UI polls that privacy-safe state and renders an indeterminate progress indicator with reduced-motion support.
• D-8: local Web owns a real default Debugger harness. When workspace Session discovery is available and no explicit harness was configured, the server resolves a built-in single-session Qoder harness. Explicit harness configuration still wins. After workspace selection, live runs use that server-only directory as cwd and the default capability source root; no absolute path is returned to the browser and no scripted demo executor is substituted in production.
• D-9: Sessions reuses the Inspector workbench instead of only its discovery. The workspace provider returns the same privacy-filtered HarnessInspectorReportV1 projection consumed by scripts/harness-inspector/ui/workbench.html. Studio rewrites that complete workbench interaction in React: Capability/Date navigation, scope metrics, evidence workbench cards, and the retained Session drawer are React-owned state and components. The original Inspector stylesheet/class contract stays the visual source, while workbench.js remains only the standalone HTML renderer and is never executed by Studio. The compact catalog remains an explicit secondary view for two-Session selection and comparison.

Acceptance Scenarios

• AC-1: Studio starts with no data arguments and presents an enabled Open workspace action on Overview and Sessions.
• AC-2: Choosing a directory is allowed only from a same-origin loopback request, returns no absolute path to the browser, and does not upload or copy the project's files. Cancelling leaves the active workspace unchanged.
• AC-3: Selecting a project directory runs the Inspector-owned provider discovery against that workspace and produces a newest-first Session list with provider, prompt, observed time, and tool-call count. One unavailable or failed provider does not hide sessions from other providers.
• AC-4: Selecting a Session opens its real retained Session Debugger projection. No sample session is substituted when the workspace has data.
• AC-5: The user can select exactly two sessions from the current workspace and open Compare without supplying an experiment manifest or evidence path.
• AC-6: Session Compare names both sessions and shows observed differences for status, retained event count, tool-call count, message count, and tool sequence. It labels missing evidence and makes no winner claim.
• AC-7: Replacing or disconnecting the workspace clears the prior Session, Compare, and Artifact selection. Discovery is read-only and never writes into the workspace or native host session stores.
• AC-8: Empty-state UI copy does not instruct the user to restart with --inspector, --evidence, --harness, or --artifacts for browsing and comparing retained sessions.
• AC-9: Workspace and Session navigation remain keyboard usable with no document-level horizontal overflow at 1440x900, 1024x768, and 390x844.
• AC-10: The root CLI contract can later expose better-harness web as a workflow command that starts the same empty Studio server; it does not add directory-selection flags to the primary Web workflow.
• AC-11: During a slow workspace open, the button is disabled, an animated live status first reports directory selection and then Session discovery, and completion automatically replaces the intake with the discovered Session list. No made-up percentage or absolute path is shown.
• AC-12: The local Web Debugger is enabled without --harness, identifies itself as the workspace default, opens the existing live-run composer, and executes through the real built-in Qoder adapter in the selected workspace. A caller-supplied harness/runtime remains authoritative, and a Studio server without workspace discovery does not silently acquire a runnable endpoint.
• AC-13: After selecting a project workspace, Sessions defaults to the native Harness Inspector workbench backed by the workspace's structured report. Capability/date navigation, scope metrics, workbench rows, and the retained Session drawer execute as React components matching the complete workbench.html design; Studio does not load or execute workbench.js. A visible, keyboard-usable view switch exposes Catalog & Compare without losing the active workspace or requiring a restart/CLI argument. When a provider cannot supply structured Inspector data, Studio falls back to the catalog with an actionable status rather than an empty workbench.

Non-goals

• Treating observational Session Compare as an experiment verdict.
• Uploading an entire repository or agent home to the loopback server.
• Reimplementing host transcript discovery inside the Studio package or UI.
• Maintaining an independent visual language for the React Inspector; the standalone workbench.html and its stylesheet remain the design contract.
• Editing, replaying, or writing back into imported sessions.
• Shipping the public better-harness web package boundary in this first UI migration; the server and packaged-app ownership must be resolved first.
• Faking an out-of-box run with a production scripted executor or bypassing the selected host's normal authentication and permission boundaries.

Plan and Tasks

1. Introduce the workspace session contract

Add same-origin open/disconnect routes around a cross-platform native directory picker. Keep the absolute path server-side and make the discovered workspace scope the dynamic owner for Session routes.

2. Make Sessions the primary observed-data surface

Replace startup-flag-driven empty states with an Open workspace action, invoke the Inspector-owned multi-provider collector in process, render its Session catalog, and open real retained Session evidence from the selected row.

3. Add observational Session Compare

Allow two Session selections, derive a compact comparison model from retained records, and render a docked two-session comparison without a winner verdict. Keep frozen harness-compare evidence as a separate surface.

4. Scope Artifact View below Session

Resolve artifacts from a Session discovered for the selected project workspace when the adapter exposes them. Until then, show an honest session-scoped empty state rather than a loose global artifact picker.

5. Prepare the launcher boundary

Keep Studio's server start independent of data arguments. In a follow-up, package the built Studio runtime so the root command registry can dispatch better-harness web without repository-only paths.

6. Provide the local default Debugger harness

Resolve a compiler-valid built-in Qoder harness only for the local workspace-discovery host. Keep explicit harness configuration authoritative, bind execution to the selected workspace on the server, label the active default in the UI, and exercise the same AG-UI/live-run path as configured harnesses.

7. Mount Inspector as the primary Sessions workbench

Build a bounded HarnessInspectorReportV1 from the same normalized provider sessions during workspace discovery, retain it only in the server-side active workspace, and expose it through a workspace-scoped structured endpoint. Rewrite the complete Inspector workbench UI as React components using the standalone HTML/CSS contract, with no workbench.js execution, plus an accessible Inspector/Catalog & Compare switch and a catalog fallback.

Test and Review Evidence

• AC-1/AC-8: empty-start model and Playwright assertions for UI copy and actions.
• AC-2/AC-3/AC-7: HTTP tests with an injected picker/provider for same-origin access, cancellation, atomic replacement, disconnect, provider diagnostics, path redaction, and read-only discovery.
• AC-4: browser test that selects a retained session and verifies its prompt and real tool-call projection.
• AC-5/AC-6: model and browser tests selecting two sessions and rendering an observational comparison with no winner language.
• AC-9: Playwright screenshots, keyboard focus, horizontal overflow, browser console, and page-error checks at all three required widths.
• AC-10: CLI inventory/dispatch tests belong to the packaging follow-up.
• AC-11: HTTP tests pause the injected chooser and provider to verify the two status stages; Playwright verifies the live discovery message, progress indicator, disabled action, and automatic transition to the Session list.
• AC-12: server tests resolve and execute the default harness with an injected deterministic executor while asserting the selected workspace cwd and source root; Playwright opens Debugger after workspace discovery and completes a live run through the default AG-UI path.
• AC-13: provider and server tests assert a privacy-filtered structured workspace report, Git/Session correlation, and no absolute-path disclosure. Playwright verifies the React-owned Inspector workbench is the default Sessions surface, opens a retained Session through its Date navigator, switches to Catalog & Compare, repeats wide/compact/narrow overflow plus console/page-error checks, and asserts that Studio never requests the legacy workbench.js runtime.

Implementation evidence (2026-08-20):

• npm test in packages/harness-studio: 18 files, 121 tests passed, including controlled chooser/discovery stages and default-harness execution rooted at the selected workspace.
• npm run test:browser in packages/harness-studio: 16 Playwright tests passed, including the workspace intake, discovered Session detail, Compare, the default live Debugger flow, animated discovery status, wide/compact/narrow screenshots, keyboard focus, overflow, console, and page error checks. The Sessions flow also exercises the React Inspector drawer and asserts that no legacy Inspector script is loaded.
• npm test at the repository root: 99 files, 1412 tests passed.
• A live in-process discovery smoke against this repository returned the bounded React Inspector report with 100 Sessions and 50 commits: Qoder 79, Codex 16, and Claude 5.

Risks

• Browser directory inputs expose relative paths and bytes, not a portable absolute path. The loopback server therefore owns the native picker and must never expose the selected absolute path back to the page.
• Session records may contain sensitive prompts or tool output. Imports remain loopback-only, temporary, bounded, and never leave the local server.
• Host transcript formats differ substantially. Studio must reuse the bounded provider discovery and privacy-safe projection already owned by Inspector.
• Native directory chooser availability differs across Windows, macOS, and Linux. Platform implementations must use fixed commands without a shell and return an actionable unavailable state when no chooser exists.
• Large histories can exhaust memory. Discovery retains Inspector's global Session bound and hydrates only selected recent candidates.
• The Inspector workbench is a substantial retained-evidence renderer. Studio must reuse its assets lazily and keep the compact catalog available if the structured report or client runtime cannot be mounted.