Launch nested Canvas Designer shell from Wizard

[nicolehaugen]

Summary

• Launch an app-native nested Canvas Designer session from the Wizard's Generate canvas dialog, starting from the project's default branch without changing the Wizard's project.
• Send a versioned, immutable handoff of active phase IDs and explicit preset, extension, and bundle selections. The child saves the handoff in its session artifacts; the Designer extension bundled with the installed Wizard plugin validates it on open.
• Keep this increment shell-only. The child opens the plugin-provided canvas by ID; no provider files or selected design packages are installed into the child checkout. Designer pages and package installation are deferred.

Stack

Depends on #38 for the standalone Canvas Designer provider. Native stack order is #35 → #38 → #36 (PR numbers do not determine stack order).

Verification

• Wizard unit tests: 313 passed; standalone provider tests: 4 passed; Designer browser tests: 3 passed.
• Diff against Add standalone Canvas Designer provider to Wizard plugin #38 is one Wizard launch commit; no provider/bootstrap files are changed.

[Copilot]

Copilot review overview

🟡 Changes recommended

The provider is copied to an undiscoverable extension location, and stale dialog state can bypass catalog-change validation.

Review effort: Balanced
Findings: 1 · 1

Open (2)

• Install provider in a supported extension directory · New
• Submit the snapshot captured when the dialog was rendered · New

What changed in this PR

Adds nested Canvas Designer session launching from the Wizard using validated, versioned handoffs and a minimal child-session shell.

Changes:

• Enables Designer launch from the Wizard dialog.
• Adds catalog fingerprinting, handoff validation, and shell provider bootstrapping.
• Adds unit/E2E coverage and synchronizes Wizard version metadata.

File	Description
README.md	Updates Wizard version.
plugins/​spec-kit-copilot-wizard/​plugin.json	Bumps plugin to 0.3.0.
.github/​plugin/​marketplace.json	Updates marketplace versions.
.../​ui/​modals.js	Clarifies deferred installation messaging.
.../​ui/​canvas-designer-dialog.js	Enables launch request handling.
.../​test/​modals.test.mjs	Updates modal assertions.
.../​test/​designer-launch.test.mjs	Tests handoff and shell launch behavior.
.../​test/​canvas-designer-dialog.test.mjs	Tests dialog launch behavior.
.../​server/​handlers-designer.mjs	Validates and dispatches Designer launches.
.../​server.mjs	Registers the launch endpoint.
.../​README.md	Documents nested Designer sessions.
.../​e2e/​server.mjs	Enables launch in the E2E fixture.
.../​e2e/​canvas-designer.spec.mjs	Covers launch through the browser.
.../​catalog/​designer-fingerprint.mjs	Fingerprints eligible design catalog entries.
.../​canvas-runtime/​snapshot.mjs	Adds the Designer fingerprint to snapshots.
.../​speckit-canvas-designer/​server.mjs	Serves the minimal Designer shell.
.../​speckit-canvas-designer/​handoff.mjs	Validates and reads handoffs.
.../​speckit-canvas-designer/​extension.mjs	Registers the Designer canvas.
.../​speckit-canvas-designer/​bootstrap.mjs	Copies the provider into the child session.

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

[Copilot]

Copilot review overview

🟡 Changes recommended

Provider bootstrap can follow a symlinked extension directory and write outside the child worktree.

Review effort: Balanced
Findings: 1

Open (1)

• Reject symlinked extension parents before copying · New

Resolved since last review (2)

• Install provider in a supported extension directory
• Submit the snapshot captured when the dialog was rendered

[Copilot]

Copilot review overview

🔵 Needs a closer look

Concurrent provider lifecycle callbacks can leak servers or return stale URLs, and release descriptions need synchronization.

Review effort: Balanced
Findings: 1

Open (1)

• Reject symlinked extension parents before copying

[Copilot]

Copilot review overview

🟡 Changes recommended

The Wizard plugin needs a synchronized new version so installed 0.3.0 users can receive this launch functionality.

Review effort: Balanced
Findings: 1 · 1

Open (2)

• Reject symlinked extension parents before copying
• Bump Wizard plugin version and synchronize release metadata · New

[Copilot]

Copilot review overview

🟡 Changes recommended

Empty catalogs can permanently disable launch, and the changed Wizard plugin version is not synchronized across release metadata.

Review effort: Balanced
Findings: 1 · 2

Open (3)

• Reject symlinked extension parents before copying
• Empty catalogs prevent the dialog from becoming launch-ready · New
• Bump Wizard plugin version and synchronize release metadata

[Copilot]

Copilot review overview

🟡 Changes recommended

Launch dispatch blocks on agent completion, and the Wizard plugin version was not synchronized with its changed implementation.

Review effort: Balanced
Findings: 1 · 3

Open (4)

• Reject symlinked extension parents before copying
• Awaiting session.send blocks the 202 queued response · New
• Empty catalogs prevent the dialog from becoming launch-ready
• Bump Wizard plugin version and synchronize release metadata

[Copilot]

Copilot review overview

🟡 Changes recommended

Deferred dispatch and concurrent bundle inspection currently have correctness issues.

Review effort: Balanced
Findings: 1 · 2

Open (3)

• Concurrent inspections re-enable choices and include deselected members · New
• Awaiting session.send blocks the 202 queued response
• Empty catalogs prevent the dialog from becoming launch-ready

Resolved since last review (3)

• Reject symlinked extension parents before copying
• Install provider in a supported extension directory
• Bump Wizard plugin version and synchronize release metadata

[Copilot]

Copilot review overview

🟡 Changes recommended

Catalog readiness can be published before preset hydration completes, and one stale-pipeline race returns an internal error.

Review effort: Balanced
Findings: 1

Open (1)

• Gate readiness on hydrated preset catalog · New

Resolved since last review (3)

• Concurrent inspections re-enable choices and include deselected members
• Awaiting session.send blocks the 202 queued response
• Empty catalogs prevent the dialog from becoming launch-ready

Previously missed (1)

In code that hasn't changed since last review

Handle invalid second pipeline snapshot as stale

plugins/​spec-kit-copilot-wizard/​extensions/​speckit-wizard-canvas/​server/​handlers-designer.mjs:127

Treat an invalid second pipeline snapshot as stale instead of letting it escape as a 500. The first snapshot is validated, but if the pipeline changes to an invalid ID or exceeds 30 phases before this second read, designerPhaseIds(current) throws inside the condition; the top-level server catch then reports an internal error rather than the intended reopen response for a changed pipeline.

[Copilot]

Copilot review overview

🟡 Changes recommended

State can become stale during provider readiness, and the UI incorrectly promises installation in this handoff-only increment.

Review effort: Balanced
Findings: 2

Open (2)

• Recheck catalog after readiness before dispatching the handoff · New
• Clarify dialog text that selections are handed off, not installed · New

Resolved since last review (1)

• Gate readiness on hydrated preset catalog

[Copilot]

Copilot review overview

🔵 Needs a closer look

Live nested-session and extension RPC behavior is mocked rather than exercised end to end.

Review effort: Balanced
Findings: None

Resolved since last review (2)

• Clarify dialog text that selections are handed off, not installed
• Recheck catalog after readiness before dispatching the handoff

[Copilot]

Copilot review overview

🟡 Changes recommended

Dialog readiness can mix refreshed state with stale rendered selections, causing launch failures during catalog hydration.

Review effort: Balanced
Findings: 1

Open (1)

• Launch readiness uses live state but submits a stale catalog snapshot · New