Optimize ephemeral E2E stack pinning

[ytallo]

Summary

• batch exact v2 runtime and target pins before the runner
• reapply the resolved union once after the runner
• preserve the legacy v1 path unchanged

Validation

• bash -n harness/tests/e2e/run-shadow-control-ci.sh
• python3 -m pytest .github/scripts/tests/test_harness_e2e_shadow_contract.py -q
• git diff --check

Summary by CodeRabbit

• Bug Fixes
  • Improved reliability when installing pinned worker versions during setup and post-runner operations.
  • Ensured runtime and target versions are applied consistently for Schema 2 workflows.
  • Preserved existing installation behavior for legacy schemas.

[vercel]

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Project	Deployment	Actions	Updated (UTC)
workers	Ready	Preview	Aug 20, 2026 2:57pm
workers-tech-spec	Ready	Preview	Aug 20, 2026 2:57pm

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: b5789c64-3b92-441c-84d2-ee62f3a91139

📥 Commits

Reviewing files that changed from the base of the PR and between f0ad63c and 677d5a6.

📒 Files selected for processing (1)

• harness/tests/e2e/run-shadow-control-ci.sh

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📝 Walkthrough

Walkthrough

The CI script adds retry-enabled batch installation for exact worker versions. Schema 2 installs and repins the combined runtime and target stacks. Legacy schemas keep separate target installation and repinning.

Changes

Shadow control stack handling

Layer / File(s)	Summary
Exact stack installation and schema routing harness/tests/e2e/run-shadow-control-ci.sh	Adds install_exact_stack for sorted worker pins with retries and force enabled. Schema 2 merges runtime and target versions for installation and repinning. Legacy schemas retain separate target-stack handling.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• iii-hq/workers#846: Introduces the schema 2 stack-installation and repinning logic extended by this change.

Poem

A rabbit checks each worker pin,
Then retries till the stacks fit in.
Schema two joins paths as one,
Legacy keeps its work well done.
Exact versions hop in line.

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/batch-shadow-stack-pins

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[github-actions]

skill-check — worker

0 verified, 62 skipped (no docs/).

Layer	Result
structure	✓
vale	✓
ai	✓
render	✓

Four for four. Nicely done.