chore: cut stagehand-server-v3 catchup release

[shrey150]

Why

The stagehand-server-v3 SEA binary release workflow (.github/workflows/stagehand-server-v3-release.yml) only cuts a new tag/binary build when a changeset added since the last stagehand-server-v3/v* tag explicitly lists the @browserbasehq/stagehand-server-v3 package. It doesn't look at package.json versions.

The last such changeset landed on 2026-06-09 (v3.7.2, #2217). Since then, 39 changesets have merged that touch packages/core/packages/server-v3 — including Gemini 3.5 Flash CUA support (#2273) and an AI SDK warning fix affecting act/extract/observe (#2359) — and none of them included the stagehand-server-v3 package line. So the release-detect job has returned release=false on every push for over a month, even though updateInternalDependencies: patch cosmetically bumps server-v3's package.json/CHANGELOG on every Version Packages PR, making it look like a release happened when it didn't.

This changeset is a one-time catch-up: it doesn't change any code, it just gives the release workflow a qualifying trigger so it cuts a binary build containing everything already merged to packages/core since v3.7.2.

Related: a user asked about this gap on Discord, referencing #2333 (Gemini 3.5 Flash support request).

What changed

• Added .changeset/stagehand-server-v3-catchup-release.md bumping @browserbasehq/stagehand-server-v3 (patch, 3.7.2 → 3.7.3).

E2E Test Matrix

Command / flow	Observed output	Confidence / sufficiency
Ran the exact front-matter regex from stagehand-server-v3-release.yml's detect job against the new changeset file	Parsed: @browserbasehq/stagehand-server-v3 patch matches target package: true	Proves this changeset satisfies the workflow's own detection logic and will set release=true on merge to main, advancing the tag from v3.7.2 to v3.7.3.
Verified all 13 historical stagehand-server-v3 tags against their triggering commit's changeset	13/13 correlate exactly with a changeset explicitly bumping @browserbasehq/stagehand-server-v3	Confirms the detection mechanism is real and consistent — this isn't a guess about how the pipeline works.
Scanned all 39 changesets added to main since the v3.7.2 tag commit	0/39 include a stagehand-server-v3 line	Confirms the gap is total (not partial) and this PR is the correct/only trigger needed.

Linear: STG-2587

---

Summary by cubic

Triggers a catch-up SEA binary release for @browserbasehq/stagehand-server-v3 by adding a changeset, so all core changes since v3.7.2 ship (including Gemini 3.5 Flash computer-use support).
Addresses Linear STG-2587 by closing the drift between version bumps and actual binary releases.

^{Written for commit efb5f99. Summary will update on new commits.}

[changeset-bot]

🦋 Changeset detected

Latest commit: efb5f99

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@browserbasehq/stagehand-server-v3	Patch

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[cubic-dev-ai]

No issues found across 1 file

Confidence score: 5/5

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

_{Re-trigger cubic}