ci: restore commit-addressed alpha releases for the TypeScript SDK

[miguelg719]

Why

On v3, every push published a snapshot of @browserbasehq/stagehand as <next>-alpha-<sha> under the alpha dist-tag (release-canary script + snapshot changesets config + a "Publish Canary" step in release.yml). The v4 release rewrite (#2671) dropped all three, so nothing newer than 4.0.0-alpha-49bc5b6… has shipped to npm since.

What

Port the v3 behavior onto the v4 release tooling:

• .changeset/config.json — restore snapshot: { useCalculatedVersion, prereleaseTemplate: "alpha-{commit}" } (the v3 snapshot.tag key was never part of the schema; the dist-tag comes from --tag alpha on publish).
• justfile — new _publish-typescript-alpha recipe: changeset version --snapshot → build sdk-ts → changeset publish --tag alpha --no-git-tag.
• .github/workflows/release.yml — new publish-typescript-alpha job after release-typescript. It's a separate job (rather than a trailing step as on v3) so an alpha failure can't block the Python/Go release jobs, and it only needs the node toolchain (turbo run build --filter=@browserbasehq/stagehand covers protocol → extension → sdk-ts).

Behavior matches v3: only packages with pending changesets are versioned, so the push that cuts a stable release is a no-op for the alpha job. Verified locally that changeset version --snapshot yields 4.0.3-alpha-8b75044ee9163dc3c0d18fb11eed4a12246b4a03.

No changeset — CI/release infra only.

Follow-up

Python alphas (<next>a0.dev<N> on PyPI — PEP 440 can't carry the sha) are coming in a separate PR. Go needs nothing: go get …/sdk-go/v4@<sha> already works via pseudo-versions.

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Summary by cubic

Restores commit-addressed alpha releases for the TypeScript SDK. v3 published <next>-alpha-<sha> to the alpha dist-tag on pushes; v4 dropped it. This brings back automated alphas without affecting stable releases.

• Restores Changesets snapshot config: useCalculatedVersion with prereleaseTemplate: "alpha-{commit}".
• Adds just _publish-typescript-alpha: changeset version --snapshot → build sdk-ts → changeset publish --tag alpha --no-git-tag.
• Adds a separate publish-typescript-alpha job in release.yml after release-typescript; builds @browserbasehq/stagehand via turbo and does not block Python/Go if it fails.
• Behavior matches v3: publishes <next>-alpha-<sha> only when there are pending changesets; no-op on the stable-release commit; no git tags; CI-only. Aligns with Linear AP-2885.

^{Written for commit d98d0e4. Summary will update on new commits.}

[changeset-bot]

⚠️ No Changeset found

Latest commit: d98d0e4

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

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[cubic-dev-ai]

No issues found across 3 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

Architecture diagram

sequenceDiagram
    participant GitHub as GitHub Push Event
    participant WF as release.yml Workflow
    participant RT as release-typescript Job
    participant ALPHA as publish-typescript-alpha Job
    participant PR as Python/Go Release Jobs
    participant Just as justfile Recipe
    participant CS as Changesets CLI
    participant Turbo as Turbo Build
    participant NPM as npm Registry
    participant Pkg as TypeScript SDK Packages

    Note over GitHub,NPM: CI/CD Flow for TypeScript SDK Release Pipeline

    GitHub->>WF: Push to main branch
    WF->>RT: Trigger release-typescript job
    RT->>RT: Run stable release (unchanged)
    RT-->>ALPHA: Trigger job (needs: release-typescript)

    alt Pending changesets exist
        ALPHA->>Just: Run _publish-typescript-alpha recipe
        
        Just->>CS: changeset version --snapshot
        Note over CS: Snapshot config: useCalculatedVersion + prereleaseTemplate "alpha-{commit}"
        CS->>Pkg: Version package(s) with pending changesets
        Pkg-->>CS: Apply commit-addressed version (next-alpha-sha)
        CS-->>Just: Complete

        Just->>Turbo: pnpm exec turbo run build --filter=@browserbasehq/stagehand
        Turbo->>Pkg: Build protocol → extension → sdk-ts
        Pkg-->>Turbo: Build artifacts ready
        Turbo-->>Just: Build complete

        Just->>CS: changeset publish --tag alpha --no-git-tag
        CS->>NPM: Publish package(s) with alpha dist-tag
        NPM-->>CS: Publish confirmation
        CS-->>Just: Complete
        Just-->>ALPHA: Alpha publish success
    else No pending changesets (stable release commit)
        ALPHA->>Just: Run _publish-typescript-alpha recipe
        Just->>CS: changeset version --snapshot
        CS-->>Just: No-op (nothing to version)
        ALPHA-->>WF: Skip publish, job succeeds
    end

    ALPHA-->>WF: Job complete (regardless of alpha status)
    
    Note over WF,PR: Python/Go releases not blocked by alpha job
    WF->>PR: Trigger Python/Go release jobs (parallel)
    PR-->>WF: Complete independently

    Note over NPM: Alpha packages NOT git-tagged (--no-git-tag)<br/>Dist-tag: alpha (from --tag alpha)

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_{Re-trigger cubic}