## Summary
Gate 1 only for desktop release caching:
- replaces canary `rust-cache` use with explicit exact-key
`actions/cache/restore` + `save`
- computes keys after `cargo update --workspace`, including platform,
target, Rust toolchain, Cargo manifests/locks, profile/features, and
native-toolchain inputs
- normalizes only the desktop package version so a trusted `main` canary
can warm an otherwise identical release tag
- excludes Tauri bundle directories, so installers and signed artifacts
are never cached
- adds a restore-only `cache-proof-*` tag workflow that fails unless tag
scope sees the exact default-branch cache
- adds contract tests that enforce no release-workflow cache change in
Gate 1
`release.yml` is intentionally unchanged. A cache miss remains the
current cold canary build; the release path cannot be affected by
merging this PR.
## Validation
- `scripts/test-desktop-release-cache-key.sh`
- `scripts/test-desktop-release-cache-workflow.sh`
- `scripts/test-release-ref-contract.sh`
- Ruby YAML parse of all four changed workflows
- `git diff --check`
- pre-push `branch-skew`
## Post-merge proof plan
1. Run each canary cold on trusted `main`, recording cache size/save
time and fresh artifact inventory.
2. Run each canary warm, requiring the exact-key hit and recording
restore/build time.
3. Create a disposable `cache-proof-*` tag at that same trusted `main`
SHA and dispatch **Desktop release cache tag-scope proof** from the tag.
4. Do not begin Gate 2 or modify `release.yml` unless the exact
tag-scope restore succeeds and cache transfer economics are favorable.
---------
Signed-off-by: Wes <wesbillman@users.noreply.github.com>
Co-authored-by: Carl <c7ebe626f000404285d3686e1dc74cc07cc60a9754a150041ba132e14bd3e2ec@buzz.block.builderlab.xyz>
