chore(ci): add upstream rust and bazel compat lanes by BleedingDev · Pull Request #3712 · ScriptedAlchemy/tracedecay

BleedingDev · 2026-10-12T21:08:19Z

Why the change

Adds two non-production upstream-compatibility probe lanes — a Bazel 10 flipped-incompatible-flag build on the pinned 9.3.0 and a weekly Rust nightly toolchain probe — so the next stable releases stop being hidden surprises.

Special things to note

Probe-only lanes: the pinned stable toolchain (1.99.0) and Bazel 9.3.0 stay the authority surface; no nightly adoption and no .bazelversion bump in this PR.
PR smoke runs are informational (continue-on-error); scheduled and workflow-dispatch runs fail for real when upstream moves.
The nightly probe re-pins MODULE.bazel (rust.toolchain(versions) and rustfmt_version) to a dated nightly snapshot inside the lane only and never commits that change.

Change outline

 .github/workflows/
+  upstream-compat.yml   # weekly cron + workflow_dispatch + PR smoke trigger

upstream-compat (cron Mon 04:00 UTC + dispatch + PR paths-lane)
├─ bazel-10-readiness
│    pinned Bazel 9.3.0 with 10.0 flipped incompatible flags
│      --experimental_fetch_all_coverage_outputs
│      --experimental_split_coverage_postprocessing
│      --incompatible_check_testonly_for_output_files
│      --incompatible_exclude_starlark_flags_from_exec_config
│      --incompatible_no_implicit_file_export
│      --rewind_lost_inputs
│    → bazel build --config=ci //crates/...
└─ nightly-rust-probe
     MODULE.bazel: "1.99.0" → "nightly/<dated snapshot>" (lane-only sed)
       versions + rustfmt_version → nightly/yyyy-mm-dd
     → bazel build --config=ci //crates/... --keep_going

Summary

Adds .github/workflows/upstream-compat.yml with the two probe lanes above.
Weekly scheduled run plus workflow_dispatch (with an optional nightly-date input) so upstream breakage is caught early, before it lands in stable.

Motivation

Rust 1.99.0 / Bazel 9.3.0 / rules_rust 0.74.0 are all current as of the probe design, but Bazel 10 already names its next incompatible-flag flips and the next Rust stable follows days later. This lane converts "we find out at release time" into "we find out weekly", without sending any production lane to nightly or 10.0.

Changes

.github/workflows/upstream-compat.yml (new): two informational compatibility lanes. Each runs on ubuntu-latest with the shared .github/actions/setup-bazel composite action and its own disk-cache key, keeps the pinned toolchain as authority, and is non-blocking on PR smoke runs.

Test plan

The affected Bazel targets pass
bazel build //... passes when the change crosses package boundaries
Tested manually (lane file runs on this PR via its pull_request paths trigger; the PR lanes are the smoke run)

Checklist

CHANGELOG.md updated (under [Unreleased] if no version bump)
No secrets, credentials, or .env files included
Breaking changes documented (if any)

changeset-bot · 2026-10-12T21:08:24Z

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Latest commit: b8f6cd2

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.

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devin-ai-integration

Devin Review found 4 potential issues.

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devin-ai-integration · 2026-10-12T21:10:01Z

+  group: upstream-compat-${{ github.event_name == 'pull_request' && github.event.pull_request.number || 'upstream' }}
+  cancel-in-progress: true


🟡 Manual probe cancels weekly master probe

When a manual run starts during the weekly probe, cancel-in-progress cancels the scheduled run. Both runs share the upstream group, even across branches, so the weekly master result is lost.

Learn more

Scheduled runs check master, while workflow dispatch can run on another branch. Both events resolve the group suffix to upstream, and the workflow cancels any in-progress run in that group. A manual probe can therefore replace an unfinished scheduled master probe with a result from a different revision.

Example: The Monday master probe starts at 04:00. A maintainer dispatches the workflow on a feature branch at 04:15. GitHub cancels the master probe; only the feature-branch result remains.

Recommended fix: Give scheduled master runs and manual dispatches separate concurrency groups, with a ref- or input-specific group for dispatches. Preserve the PR-number group for superseded PR smoke runs.

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devin-ai-integration · 2026-10-12T21:10:02Z

+          bazel build --config=ci \
+            --experimental_fetch_all_coverage_outputs \
+            --experimental_split_coverage_postprocessing \
+            --incompatible_check_testonly_for_output_files \
+            --incompatible_exclude_starlark_flags_from_exec_config \
+            --incompatible_no_implicit_file_export \
+            --rewind_lost_inputs \
+            //crates/...


🟡 Coverage flips escape Bazel readiness probe

When Bazel's coverage defaults break coverage, bazel build still passes this probe. The two coverage flags do not exercise coverage collection or postprocessing without a coverage run.

Learn more

The readiness lane passes two coverage-related flags to a build. Bazel builds targets without collecting coverage, so it never invokes the coverage output collection or postprocessing those flags change. A successful build therefore does not establish compatibility with those Bazel defaults.

Example: A coverage postprocessor fails with the split-postprocessing default. The weekly bazel build succeeds because it never runs a coverage postprocessor, leaving that break undetected.

Recommended fix: Add a bazel coverage probe over a representative test target with these flags, or remove the coverage flags from the claimed readiness coverage until a coverage run exists.

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devin-ai-integration · 2026-10-12T21:10:03Z

PR cleanup

+  pull_request:
+    paths:
+      - .github/workflows/upstream-compat.yml


🟡 Closed PR keeps compatibility builds running

Closing a PR during its smoke run does not cancel upstream-compat jobs. PR cleanup targets only CI runs, leaving these builds occupying runners until completion or timeout.

Learn more

The PR smoke trigger starts two jobs that each allow up to four hours. The existing PR cleanup searches only ci.yml runs when a PR closes. No close event enters this workflow's PR-number concurrency group, so these compatibility jobs continue to use shared hosted-runner capacity after closure.

Example: A PR is closed ten minutes into a cold nightly build. CI's cleanup cancels its own runs, but the nightly and Bazel readiness jobs keep running until they finish or hit their timeouts.

Recommended fix: Extend the closed-PR cleanup to cancel this workflow's runs too, using the same PR ownership and start-time checks, or add a trustworthy close-triggered cancellation path.

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devin-ai-integration · 2026-10-12T21:10:04Z

+          sed -i "s|versions = \[\"1\.99\.0\"\]|versions = [\"nightly/$NIGHTLY_DATE\"]|" MODULE.bazel
+          sed -i "s|rustfmt_version = \"1\.99\.0\"|rustfmt_version = \"nightly/$NIGHTLY_DATE\"|" MODULE.bazel


🟥 Nightly date executes runner commands

A dispatched nightly-date containing $(...) executes commands when sed expands $NIGHTLY_DATE inside double quotes. The command runs in the workflow's runner context before the Bazel probe.

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chore(ci): add upstream rust and bazel compat probe lanes

b8f6cd2

devin-ai-integration Bot reviewed Oct 12, 2026

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ScriptedAlchemy merged commit cb7ce0c into ScriptedAlchemy:master Oct 12, 2026
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chore(ci): add upstream rust and bazel compat lanes - #3712

chore(ci): add upstream rust and bazel compat lanes#3712
ScriptedAlchemy merged 1 commit into
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ultramodernjs:chore/upstream-compat-lanes

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		group: upstream-compat-${{ github.event_name == 'pull_request' && github.event.pull_request.number \|\| 'upstream' }}
		cancel-in-progress: true

		sed -i "s\|versions = \[\"1\.99\.0\"\]\|versions = [\"nightly/$NIGHTLY_DATE\"]\|" MODULE.bazel
		sed -i "s\|rustfmt_version = \"1\.99\.0\"\|rustfmt_version = \"nightly/$NIGHTLY_DATE\"\|" MODULE.bazel

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Why the change

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BleedingDev commented Oct 12, 2026 •

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