ci: hand prepared macOS SDK to downstream jobs

[thepastaclaw]

Issue being fixed or feature implemented

Fork pull request workflows can restore GitHub Actions caches but cannot persist a missing macOS SDK cache entry. The trusted build-depends cache-check job prepares the SDK, but both the downstream depends build and macOS source build previously required a successful cache restore, so the prepared SDK was lost between jobs.

Fixes#7461.

What was done?

• Expose a short-lived same-run SDK artifact from the macOS depends cache-check job whenever it prepares the SDK.
• Restore the persistent SDK cache first in both downstream consumers, then download the prepared artifact when the exact cache entry is unavailable.
• Fail with an explicit error if neither the cache nor the same-run artifact is available.
• Keep the existing trusted cache-warming behavior unchanged.

How Has This Been Tested?

• actionlint schema and expression validation for the three changed workflows (ignoring the repository's pre-existing ShellCheck warnings)
• Ruby YAML parsing for the three changed workflows
• test/lint/lint-whitespace.py
• git diff upstream/develop...HEAD --check
• git show --check
• git verify-commit HEAD
• Independent exact-commit code review: zero findings, recommendation ship

The hosted cache/artifact transfer itself requires a live GitHub Actions run and will be validated by this pull request's CI.

Breaking Changes

None.

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated relevant unit/integration/functional/e2e tests (workflow-only change; validated with workflow and repository linters)
• I have made corresponding changes to the documentation (not applicable)
• I have assigned this pull request to a milestone (for repository code-owners and collaborators only)

[thepastaclaw]

🔍 Review in progress — actively reviewing now (commit 7a80e79)

[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: d146b62a-01ce-48f0-b9a1-242b2be742a6

📥 Commits

Reviewing files that changed from the base of the PR and between ed436ec761f0564dfeb5d62dba239b5c7cd79a30 and 7a80e79.

📒 Files selected for processing (3)

• .github/workflows/build-depends.yml
• .github/workflows/build-src.yml
• .github/workflows/build.yml

🚧 Files skipped from review as they are similar to previous changes (3)

• .github/workflows/build-src.yml
• .github/workflows/build-depends.yml
• .github/workflows/build.yml

---

Walkthrough

The CI workflows coordinate macOS SDK preparation through cache restoration and short-lived artifacts. The depends workflow prepares and uploads SDKs on cache miss, exposing the artifact name as a job and reusable-workflow output. The source-build workflow accepts that artifact and uses it when cache restoration misses, otherwise failing explicitly. The main workflow passes the depends output into the macOS build.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
participant Depends as depends-mac
participant Cache as SDK cache
participant Artifact as SDK artifact
participant SourceBuild as build-src
Depends->>Cache: restore SDK cache
alt cache miss
Depends->>Artifact: upload prepared depends/SDKs
end
SourceBuild->>Cache: restore SDK cache
alt cache miss and artifact provided
SourceBuild->>Artifact: download prepared SDKs
else cache miss and no artifact
SourceBuild-->>SourceBuild: fail with error
end

Loading

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: passing a prepared macOS SDK to downstream CI jobs.
Description check	✅ Passed	The description matches the workflow changes and the stated fix for missing macOS SDK caches.
Linked Issues check	✅ Passed	The PR implements the linked fix by transferring the prepared SDK via same-run artifact and using it on cache miss.
Out of Scope Changes check	✅ Passed	The changes stay focused on macOS SDK cache fallback and artifact handoff, with no clear unrelated additions.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
Inline comments:
In @.github/workflows/build-depends.yml:
- Around line 102-107: Update the prepare-sdks step to avoid expanding workflow
inputs directly in shell-executed template expressions; pass the required input
through the step’s environment and reference that environment variable within
the run block. Preserve the existing mac target condition, SDK setup command,
and artifact output behavior.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: e2224c18-c02d-41c2-8142-348d9da05da4

📥 Commits

Reviewing files that changed from the base of the PR and between f2b15fb and ed436ec761f0564dfeb5d62dba239b5c7cd79a30.

📒 Files selected for processing (3)

• .github/workflows/build-depends.yml
• .github/workflows/build-src.yml
• .github/workflows/build.yml