fix(zed): pin language server download to engine release tag

[hellovai]

Problem

The Zed extension fails to start the BAML language server with:

no asset found matching "baml-cli-baml-language-0.12.2-nightly.20260625.d-aarch64-apple-darwin.tar.gz"

The extension resolved the baml-cli binary via latest_github_release, which returns the newest release across the whole repo. But the repo publishes two independent release lines:

Release line	Tag	Asset naming
Engine / baml-cli	0.223.0	baml-cli-0.223.0-<target>.tar.gz ✅ (what the extension wants)
baml-language-* nightlies	baml-language-0.12.2-nightly.20260625.d	baml-language-…-<target>.tar.gz

The nightly line currently holds GitHub's "latest" pointer, so release.version became the nightly tag and the baml-cli-{version}-{target} template produced an asset name that doesn't exist.

Fix

Pin the lookup to the engine release tag — the extension's own CARGO_PKG_VERSION (kept in sync with extension.toml via tools/versions/zed.cfg) — using github_release_by_tag_name instead of latest_github_release. The extension version and the language-server binary it downloads now stay locked together, and the nightly line is ignored entirely.

Also corrects a stale Cargo.lock version (0.218.0 → 0.223.0).

Verification

cargo check passes clean. With the extension at 0.223.0, the asset resolves to baml-cli-0.223.0-aarch64-apple-darwin.tar.gz, which exists on the engine release.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Language-server downloads now use a fixed release version instead of always following the latest GitHub release.
  • This helps keep the installed engine aligned with the app version, reducing mismatches and unexpected updates.

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 5af7e748-8fa7-431b-8cb1-34cfb8682d7a

📥 Commits

Reviewing files that changed from the base of the PR and between 6105c59 and 9fdcc64.

⛔ Files ignored due to path filters (1)

• engine/zed/Cargo.lock is excluded by !**/*.lock

📒 Files selected for processing (1)

• engine/zed/src/lib.rs

---

📝 Walkthrough

Walkthrough

The engine language-server lookup now derives its GitHub release tag from the crate version and resolves the download from that fixed tag instead of the latest release pointer.

Changes

Pinned engine release lookup

Layer / File(s)	Summary
Version-tagged release resolution engine/zed/src/lib.rs	Defines a crate-version release tag and uses it in the GithubRelease path to fetch the matching GitHub release by exact tag name.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

Poem

A tiny hop, a version’s tune, 🐇
I nibble tags beneath the moon.
No “latest” breeze can blow me stray,
I hop to versions, safe and stay.
Zip! The release is pinned just right,
A tidy carrot in the night.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: pinning the Zed language server download to the engine release tag instead of latest.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch hellovai/fix-zed

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[github-actions]

⏭️ Performance benchmarks were skipped

Perf benchmarks (CodSpeed) are opt-in on pull requests — they no longer run on every push. They always run automatically after merge to canary/main.

To run them on this PR, do any of the following, then push a commit (or re-run CI):

• Add RUN_CODSPEED=1 to the PR description, or
• Include run-perf or /perf in the PR title or any commit message.

[sxlijin]

#3853 should take care of this