[lawrencecchen]

Follow-up from the #31013 review (lead decision, 15:3xZ). Since #30912, the nightly runs step scripts from scripts/ci/nightly-steps/ in the resolved build commit's checkout, under the tip's workflow. CMUX_TUI_TREE_SAME_PATHS only made the build commit carry the tip's nightly.yml and Chief lockfile. So a published commit behind the tip, whose step scripts differ from the tip's, could run older copies of steps that the tip's workflow names.

Change

• resolve-nightly-cmux-tui-client adds scripts/ci/nightly-steps to CMUX_TUI_TREE_SAME_PATHS.
• pin-cmux-tui.sh compares git rev-parse <rev>:<path>. For a directory this is its tree object, so a candidate that differs from the tip in any step script is skipped. The message is "scripts/ci/nightly-steps differs from the tip", the same as for nightly.yml today.

Cost: when the tip changed a step script after the newest published commit, the nightly now takes a newer published commit, or builds the tip while its tree publishes (resolve-tree-pending.sh). That is the same as after a nightly.yml change today. In the last 14 days on feat, 8 of 41 step-script commits did not also change nightly.yml (nightly.yml changed in 239 commits). So this adds a skip rarely.

Out of scope, tracked in #31127: other scripts that the tip's workflow runs from the build commit's checkout (scripts/ci/*.py, scripts/cmux-next/*.sh, 90 steps in 19 jobs). The lead decided not to widen this list for them, because each path makes skips more frequent. #31127 proposes the root-cause fix: steps that run tip-workflow logic take their scripts from the workflow commit's checkout.

Red and green (test first, then fix)

The new case in scripts/cmux-next/tests/pin-cmux-tui-resolve-newest.test.sh runs nightly.yml's own CMUX_TUI_TREE_SAME_PATHS. It publishes a commit with an older step script, then a tip with a newer one. The resolver must refuse the older commit with a clear message, and must accept it once the tip's tree is published.

• Red at 349227ff466 (test only): FAIL: nightly must not resolve a published revision with an older nightly step script.
• Green at 24a7029fc3b (fix) and at this head: PASS.
• cmux-next.yml already runs this test file. No CI job, step or gate is added.

Observed / Not run

• Observed:
  • The red and green results above.
  • All 124 tests that read nightly.yml give the same results as at base 1f80a9fc5c7. The same 10 base reds fail on both sides.
  • test_workflow_file_size.py passes (458,338 bytes after merging ci(nightly): headroom under the size budget (14 more run blocks, step notes into scripts, expressions through env) #31013).
  • test_cmux_next_media_tree_fallback.py passes (the other user of the variable, in cmux-next-media.yml, which this PR does not change).
  • prepush-gate.py passes.
• Not run: no nightly run.

Risk tier: high (risk_tier.py: nightly.yml is on the release path).

Changelog

none

[github-actions]

cmux status _{(one comment, edited in place; each line is updated by the job that owns it)}

Review 9fed58b: HQ feed card · gallery before/after runs · checks

App of this head (app.zip, kept 1 day)

gh workflow run reload-build.yml -R manaflow-ai/cmux --ref feat-cmux-next -f tag=pr31121 -f ref=fix/nightly-same-paths-steps -f platform=macos -f backend_mode=local

Shipped in:

• cmux NEXT nightly 1.0.0-nightly.4132727143001 (fe90490c5d)
• cmux NEXT nightly 1.0.0-nightly.4132868957301 (e3ba279462)

[lawrencecchen]

Review (subagent, correctness first): SHIP at 9fed58b

What the reviewer confirmed:

• For a directory, the resolver compares the tree object, so equal means byte-identical contents. A missing directory gives missing on both sides.
• In the resolver's shallow checkout (fetch-depth 64, at most 50 commits searched), a directory path behaves the same as a file path. The list has no quoting or word-splitting problem.
• Only nightly.yml:2725 sets the variable in nightly.yml. cmux-next-media.yml keeps its own value, and no test pins the old value.
• Red at 349227ff466, green at this head. With the directory removed from the list, the test fails again. The test reads nightly.yml's actual value.
• Cost: a tip that changes only step scripts still resolves, because its tree key equals the published key. The tree-pending path builds the tip. When no commit is found, the error says how to start a publisher. No commit pattern makes every nightly fail.
• The merge adds only the word, the comment line and the test.

Non-blocking, and present before this PR: other scripts the tip's workflow calls from the build checkout (scripts/ci/*.py, scripts/cmux-next/*.sh) are not covered by the list yet.