Feature tryouts

Feature tryouts connect release-note links to trusted product interactions. Use this skill to choose the least invasive useful experience, keep behavior feature-owned, bind guidance to the correct UI instance, fail closed, and validate the real journey.

The authoritative contributor contract is src/vs/workbench/contrib/onboarding/README.md. Read it before implementation. This skill owns the execution workflow and must not duplicate a catalogue of current tryouts.

1. Classify the experience

Choose the least invasive level that provides value:

A spotlight alone can be useful. A tryout does not need to reproduce the complete feature.

2. Establish ownership and side effects

Before editing, answer:

1. What useful state should the user reach?
2. Which component owns that behavior?
3. What may the tryout change?
4. What must remain an explicit user action?
5. What prerequisites can be missing?
6. Can several matching controls be visible?
7. Does preparation need an exact editor, session, or widget?
8. Does execution cross into the Agents window?
9. Is this an AI feature subject to Chat, provider, model, workspace, or managed-policy gates?
10. How will cancellation suppress late asynchronous effects?

Prefer feature-owned contributions and commands. Shared onboarding code should provide reusable lifecycle and presentation primitives, not feature policy.

3. Choose a presentation

Add a feature-owned presentation only when the built-in types cannot express the required lifecycle safely.

Canonical implementations:

• diffEditorTryout.contribution.ts — isolated editor sample.
• modelPickerTryout.contribution.ts — scoped multi-instance target.

4. Preserve the trust boundary

Release notes are fetched content. They may identify a tryout, but they never define executable behavior.

Requirements:

• Markdown contains only one stable, registered tryout ID.
• Installed product code owns titles, descriptions, commands, arguments, prompts, paths, samples, setup actions, and availability checks.
• Unknown, malformed, unavailable, and stale IDs fail closed.
• Commands retain their normal preconditions, confirmation, permission, and undo behavior.
• Availability is rechecked after asynchronous preparation and immediately before execution.
• Setup actions are offered explicitly and never run while rendering release notes.
• External vscode://tryout/<id> links contain only the registered ID and always require the product confirmation. External launch defaults to allowed; set allowExternalLaunch: false when a tryout must remain in-product only.

Never automatically:

• trust a workspace;
• enable a setting;
• install an extension;
• accept a confirmation;
• select a model or provider;
• submit Chat input;
• save, create, or modify a user resource unless the described command normally does so after a user action.

Use stable, namespaced IDs. Do not repurpose an existing ID because old release notes remain available.

5. Own and scope spotlight targets

Use a feature-owned adapter to resolve controls through their owner's normal APIs, following the contributor guide. Existing owner-marked targets through markOnboardingTarget remain supported. Never query another component's classes or DOM structure.

Unique targets

Use an unscoped target only when at most one matching control can be visible in the target window.

Multi-instance targets

Editors, Chat widgets, split panes, and repeated controls require a run scope:

1. The adapter captures the exact UI owner through its feature API and binds it to a run scope.
2. The launch presentation returns { kind: 'prepared', targetScope }.
3. A dedicated adapter command can instead return { targetScope } when its command payload sets captureTargetScope: true.
4. The sequence resolves targets only within that scope.
5. Missing or stale scope fails closed instead of falling back to another visible instance.

Scopes are opaque run identities. They are not selectors, persisted state, release-note input, or authorization tokens.

See onboardingTarget.ts, guidedTryoutPresentation.ts, and spotlightPresentation.ts.

6. Handle prerequisites through real product actions

Use:

• createOnboardingClickStep when activating the real target should advance;
• createOnboardingContextStep when the requested user action produces a context-key state;
• a plain spotlight step when Next or Done is the appropriate acknowledgment.

Do not manufacture diagnostics, sessions, browser navigation, selections, or saved configuration merely to make the example look complete. Explain what the user must do and let the owning feature perform it.

7. Handle Chat and AI examples

Use isAI: true and include the feature's normal Chat visibility and enablement conditions.

Chat examples must:

• prepare an isolated draft or bind to an exact existing widget;
• never call acceptInput;
• preserve other drafts and running conversations;
• recheck provider, model, mode, extension, entitlement, workspace, and managed-policy state;
• dispose acquired models, modes, attachments, and listeners with the run;
• suppress late attachments or state changes after cancellation.

For model, provider, permission, policy, or managed-setting changes, invoke the policy-and-managed-settings skill.

8. Handle Agents-window examples

Use targetWindow: 'agents' when implementation belongs in the Agents window.

• Keep shared IDs and metadata in a layer both windows can load.
• Keep the implementation in its owning Sessions contribution.
• Import it from the appropriate sessions.*.main.ts entry point.
• Preserve the vs/sessions → vs/workbench layer direction.
• Rely on the request-scoped native handoff; do not persist or replay the request.
• A newer request must supersede and dispose the active destination run.

Invoke the sessions skill for changes under src/vs/sessions/**.

9. Apply specialist guidance

Invoke:

• accessibility for every interactive tryout;
• design-philosophy when changing visual or spotlight behavior;
• integrated-browser for Integrated Browser targets;
• sessions for Agents-window implementation;
• policy-and-managed-settings for AI controls, permissions, models, providers, or managed settings;
• memory-leak-audit for new listeners, target registrations, repeated rendering, or asynchronous lifecycles.

Reuse the existing spotlight presentation. Do not create a release-note-specific overlay.

10. Add release-note markup

Use Developer: Copy Feature Example Link to produce the encoded link. Markdown contains only the stable ID:

<!-- %IF TRYOUTS %
[Try My Feature](command:workbench.action.onboarding.tryFeature?%5B%22myFeature.guide%22%5D)
%ENDIF % -->

The surrounding prose should explain:

• what opens;
• what the user should do;
• what the example will not change;
• any prerequisite or unavailable fallback.

Use releaseNotesTryouts.md for manual validation, not as another source of feature contracts.

11. Test the contract

Add the smallest applicable coverage:

Framework references:

• onboardingTryoutService.test.ts
• onboardingTryoutActions.test.ts
• guidedTryoutPresentation.test.ts
• spotlightPresentation.test.ts
• onboardingTryoutWindow.test.ts

12. Validate and report

Run:

1. Focused unit tests.
2. Scoped ESLint.
3. npm run valid-layers-check when imports or ownership change.
4. npm run typecheck-client when TypeScript scope warrants it.
5. npm run build-fast whenever possible.
6. A real UI flow for cross-window, scoped-target, or native-browser behavior.

Clean temporary profiles, samples, logs, and processes.

The completion report should state:

• tryout ID and interaction level;
• selected presentation;
• permitted and explicitly avoided side effects;
• target scope strategy;
• prerequisites and fallback;
• files changed;
• tests and builds run;
• remaining manual validation.

Stop and redesign when

• Markdown contains a command payload, prompt, path, or arguments.
• A tryout reaches into another feature's DOM.
• A multi-instance control uses the first visible target.
• An AI example submits input or silently selects a model/provider.
• Setup silently changes configuration.
• Cancellation returns success or permits late effects.
• An Agents request is persisted for reload.
• A custom overlay duplicates Spotlight.
• Feature-local documentation copies the onboarding contributor guide.