refresh-tpu-vllm-forks

name	refresh-tpu-vllm-forks
description	Refresh Marin TPU-vLLM forks from a tpu-inference release/LKG pair, update exact SHA pins, run TPU smokes, and open the Marin PR.

Skill: Refresh TPU-vLLM Fork Stack

Read first:

@AGENTS.md

Mission

Marin maintains forks of vllm and tpu-inference with required patches. Update those forks to the latest tested upstream pair, reconcile Marin overlay commits, then open the Marin PR that pins the refreshed fork tips.

Example run: marin-community/marin#6453.

Use the same algorithm in CI and local runs. In local/manual mode, ask before external mutations: pushing fork branches, publishing the logs Gist, opening the Marin PR, or filing/updating a GitHub issue. Do not ask before required TPU smoke tests.

Repo	Role	Upstream
marin-community/vllm	Marin vLLM overlay branches.	vllm-project/vllm
marin-community/tpu-inference	Marin TPU inference overlay branches.	vllm-project/tpu-inference
marin-community/marin	Pins fork branch tips and receives the only PR.	n/a

Outcome

• If no newer upstream pair is selected and no pin metadata needs repair, exit successfully with a no-op summary.
• If the refresh succeeds, open exactly one draft PR in marin-community/marin after required smoke tests pass, and request @yonromai as reviewer.
• The PR updates Marin's fork tip SHAs, refreshes uv.lock, and reports bases, branches/tips, carried/dropped/fixed overlays, validation, and residual risk.
• Do not open fork PRs. Do not move either fork main; fork review happens via pushed branches and compare links from the Marin PR.

If a real external blocker remains after repair attempts, do not open a Marin PR. Create or update one marin-community/marin issue assigned to @yonromai, titled TPU-vLLM fork refresh blocked: <short reason>, with current pins, selected release, branch names/SHAs if created, attempted fixes, remaining failure, artifacts, and the logs Gist.

Workspace Setup

• Marin working copy:
  • GitHub Actions: use the checked-out marin-community/marin repo.
  • Local: use the human-provided Marin checkout/worktree. If it is a shared source checkout, create a dedicated worktree before editing.
• Run id:
  • GitHub Actions: ${GITHUB_RUN_ID}-${GITHUB_RUN_ATTEMPT}.
  • Local: UTC timestamp plus a short local label.
• Scratch dir: /tmp/marin-fork-refresh/<run-id>.
• Clone each fork there and add upstream:

git clone https://github.com/marin-community/vllm.git vllm
git -C vllm remote add upstream https://github.com/vllm-project/vllm.git
git -C vllm fetch --tags origin upstream

git clone https://github.com/marin-community/tpu-inference.git tpu-inference
git -C tpu-inference remote add upstream https://github.com/vllm-project/tpu-inference.git
git -C tpu-inference fetch --tags origin upstream

• Keep two top-appended Markdown logs in the scratch dir:
  • notes-summary.md: major decisions, selected bases, branch SHAs, validation outcomes, final no-op/PR/issue result.
  • sharp-edges.md: surprising failures, compatibility traps, memorable fixes, open operational risks.
• Curate the logs for major learnings only; skip routine command transcripts.
• Before opening a PR or issue, publish both logs to one GitHub Gist and link it from the PR/issue.

Algorithm

1. Read Current Pins

• Prefer managed fork pins: read current vllm and tpu-inference SHAs from root pyproject.toml tool.uv.sources; check uv.lock against them.
• Read adjacent GitHub compare-link comments to recover each current upstream base. If comments are missing, compute git merge-base <fork-sha> upstream/main and include repaired compare comments in the Marin change.
• If Marin is still on legacy package pins such as vllm-tpu==... / tpu-inference==... in lib/marin/pyproject.toml, treat this as a one-time bootstrap migration: record the package versions, do not require old fork SHAs or compare comments, and migrate to exact fork SHA pins after validation.
• Resolve any old fork SHAs in the scratch fork clones before replaying overlays.

2. Select Bases

• Use GitHub Releases for vllm-project/tpu-inference; do not use raw tags, branches, or standalone latest vLLM releases as the selection signal.
• Select the newest release where draft == false, prerelease == false, and the tag is exactly vMAJOR.MINOR.PATCH.
• Resolve that release tag to a tpu-inference commit SHA. If it matches the current Marin tpu-inference upstream base, exit no-op unless only repairing pin metadata.
• Read .buildkite/vllm_lkg.version at the selected tpu-inference release. That exact SHA is the vLLM base; verify it resolves in vllm-project/vllm.
• Inspect the LKG vLLM TPU metadata for dependency/build implications: requirements/tpu.txt, pyproject.toml, and setup.py.
• Do not walk back to older tpu-inference releases when the latest eligible release fails; fix the refresh or file a blocking issue.
• Record the selected upstream base SHAs and the reason for action/no-op.

3. Rebuild Fork Overlays

Create one branch per fork from the selected upstream base:

auto-refresh/<YYYYMMDD>/<base-id>-<shortsha>

Use the selected tpu-inference release tag as <base-id> for tpu-inference, and lkg for vLLM. Keep the same date prefix for the pair. Sanitize names. Never rewrite an existing remote refresh branch; on collision, use the next -rN suffix.

For each fork:

1. Define old_base from the current compare-link comment, old_tip from the current Marin pin, and new_base from selected upstream metadata.
2. Inventory the old Marin overlay in order: git log --reverse old_base..old_tip.
3. For each meaningful old delta, decide whether its intent is already present in new_base, still required by Marin, or broken by new upstream APIs/deps. Use patch comparison and targeted diffs for the touched files.
4. Classify each delta:
   • carry: behavior is still needed and not upstreamed;
   • drop: upstream absorbed it, it is obsolete, or it was only temporary;
   • fix: intent is still needed, but implementation must change.
5. Replay only carry and fix deltas onto new_base in old logical order. Use clean cherry-picks for carries; rewrite fixes as new commits that reference the original commit SHA(s).
6. In every retained overlay commit body, explain why it is still needed: upstream gap, Marin dependency, validation signal, and future drop condition.
7. For major non-obvious overlays/fixes, also leave a short code-adjacent rationale tied to compatibility.
8. Run git range-diff old_base..old_tip new_base..<new_tip> as the replay audit and explain every dropped or rewritten delta in the notes/PR.
9. Keep history reviewable: no conflict artifacts, unrelated refactors, or preserved commits whose behavior is now drop.

For bootstrap migrations without pin-derived old_base..old_tip, create the first managed branches from the selected upstream bases and replay only Marin fork deltas whose source and intent are explicit.

Push the finished branch to the corresponding marin-community fork.

4. Wire Marin

Update Marin root pyproject.toml so tool.uv.sources pins exact fork branch tip SHAs. Add adjacent compare comments that show the retained overlay commits against the selected upstream base:

# https://github.com/marin-community/vllm/compare/<vllm-upstream-base-sha>...<vllm-branch-tip-sha>
vllm = { git = "https://github.com/marin-community/vllm.git", rev = "<vllm-branch-tip-sha>" }
# https://github.com/marin-community/tpu-inference/compare/<tpu-inference-upstream-base-sha>...<tpu-inference-branch-tip-sha>
tpu-inference = { git = "https://github.com/marin-community/tpu-inference.git", rev = "<tpu-inference-branch-tip-sha>" }

Also make only fork-stack update changes needed in Marin:

• remove any old vllm-tpu==0.19.0 path;
• make marin-core[vllm] own the TPU-vLLM runtime stack;
• preserve worker/eval paths that intentionally combine tpu and vllm extras, unless refreshed-stack validation proves they must change;
• set VLLM_TARGET_DEVICE=tpu for TPU source-build workers.

Do not bundle unrelated usability, cleanup, or refactor work. Log those separately if found.

5. Validate

Run before PR creation:

• resolver and lockfile checks;
• focused Marin dependency/eval/worker tests;
• TPU workloads through Iris on the marin cluster, always with interactive priority, targeting v6e-4 in GCP region europe-west4;
• local troubleshooting loops on a persistent dev TPU node with the same v6e-4 / europe-west4 hardware before resubmitting Iris workloads;
• TPU import/build smoke;
• direct vllm.LLM.generate TPU smoke;
• bounded brokered Marin runtime smoke, preferring an existing script such as experiments/evals/served_qwen3_humaneval.py over writing a new smoke.

Run the brokered smoke with a bounded HumanEval sample unless a better existing brokered test is already closer to the touched code:

uv run python experiments/evals/served_qwen3_humaneval.py \
  --limit 8 \
  --region europe-west4 \
  --tpu-type v6e-4 \
  --priority interactive \
  --job-name served-qwen3-humaneval-<run-id> \
  --output-path /tmp/served-qwen3-humaneval-<run-id>

Inspect the Iris parent, broker, and worker logs; confirm the proxy served completions, lm-eval wrote HumanEval metrics and sample outputs, and no TPU/vLLM build, import, or runtime tracebacks occurred.

When a workload smoke fails, rerun the same workload against Marin's current pins on the old fork stack, using the same Iris target/priority. Fix only failures that pass on the old stack and fail on the refreshed stack. If the old stack is already broken, record it as a baseline failure; do not rewrite that workload or smoke test as part of this refresh.

6. Review Before PR

Do a PR-review-style pass over the fork commits and Marin diff. Use .agents/skills/review-pr/ as a checklist, then run ./infra/pre-commit.py --review before opening the PR and fix or respond to every finding.

Check that:

• each retained overlay has a reason to exist and a future drop condition;
• each dropped overlay is truly upstreamed, obsolete, or temporary;
• Marin edits are scoped to fork-stack update issues;
• comments, commit messages, and PR text do not overclaim validation evidence;
• required tests and baseline comparisons support the final claim.

7. Open the Marin PR

After required smoke tests pass, publish the logs Gist, push the Marin branch, and open one draft marin-community/marin PR. Request @yonromai as reviewer.

PR body:

• Above the fold: short summary, selected tpu-inference release, selected vLLM LKG, fork branch/tip SHAs, smoke-test outcome, logs Gist link, unresolved risks, and a one-line dropped-overlay summary.
• In GFM <details> blocks: base-selection evidence, carry/drop/fix table, explicit dropped-overlay reasons, smoke artifacts, and baseline-failure notes.
• Keep it readable; do not paste raw workflow logs or exhaustive command transcripts.

Done Means

• Fork main branches are unchanged and no fork PRs are opened.
• Refreshed fork branches use stable names and exact SHA pins in Marin.
• Marin pyproject.toml includes overlay compare links and uv.lock is refreshed.
• Retained overlays explain why they still exist; dropped overlays are called out with reasons.
• Required smoke tests pass before PR creation, or the unresolved blocker is in a Marin issue assigned to @yonromai.
• The two curated logs are published as one Gist and linked from the PR/issue.