jason810496 opened a new pull request, #73090:
URL: https://github.com/apache/airflow/pull/73090

   - base-branch: `main`
   - next: 
[ci/image-reuse/02-prod-dependency-layers](https://github.com/jason810496/airflow/compare/ci%2Fimage-reuse%2F01-frozen-dependencies...ci%2Fimage-reuse%2F02-prod-dependency-layers)
   
   Part 1/5 of the CI image reuse series.
   
   ## Why
   
   Prevent shared CI images from silently installing dependencies that differ 
from the lockfile.
   
   ## How
   
   Require frozen installs when publishing, disable unconstrained retries, and 
verify that reused images import the current checkout.
   
   ## Series impact (audit draft)
   
   [Sept 6–12, 2026 
UTC](https://github.com/apache/airflow/pulls?q=is%3Apr+is%3Amerged+merged%3A2026-09-06..2026-09-12)
 PR census and CI timing:
   
   | Metric | Figure |
   | --- | ---: |
   | Merged PRs / into main | 364 / 240 |
   | No dependency-manifest / CI-image / prod-image input changes | 218 (90.8%) 
/ 141 (58.8%) / 47 (19.6%) |
   | Full AMD/ARM census execution | 17,175.6 h |
   | Image-prep latency, today → 100% hit rate (CI, Py3.10) | 19.74 → 5.77 min 
(−71%) |
   | Latency break-even hit rate | ~3.5% |
   | Compute ceiling, cost-free → cost-priced replacement download | 106.4 h → 
~65.7 h/week |
   | Publisher budget proxy (daily-only cadence) | 8.0 h/run → 55.7 h/week |
   | Compute break-even hit rate (daily-only publisher) | ~85% |
   
   The purpose is to avoid rebuilding the CI image when a PR doesn't change 
package dependencies — currently, even a PR that only touches the API server or 
the UI still triggers a full CI image rebuild on every push — and real hit rate 
and end-to-end PR latency remain unmeasured pending a pilot. None of this 
changes this PR's own diff.
   
   - **Happy path:** a cache hit cuts image-prep latency by ~71% (19.74 → 5.77 
min for the dominant Python 3.10 CI case). A miss only costs about 30 extra 
seconds, so even a low cache-hit rate (as little as ~3.5%) already makes this a 
net time saver overall.
   - **Smart fallback:** the consumer probes transfer speed over the first 30 
seconds of a selected image's download; if that regresses below the reuse floor 
(added in ci/image-reuse/03-artifact-selection), it falls back to a regular 
image build — today's existing behavior — instead of waiting out a degraded 
transfer.
   - **Daily image publish workflow:** a centralized periodic workflow 
publishes CI and production images, keyed by a fingerprint of build inputs 
(dependency lockfiles, base-image digest, build args), as GitHub Actions 
artifacts for PRs to reuse.
   - **Retention:** a published artifact is only selected if produced within 
the last 48 hours, and is retained for 7 days.
   
   Series validation: 366 focused tests, 1 Docker source-mount integration 
test, and fast/manual prek checks passed.
   
   ---
   
   ##### Was generative AI tooling used to co-author this PR?
   
   - [x] Yes, with help of Codex (GPT-6) following [the 
guidelines](https://github.com/apache/airflow/blob/main/contributing-docs/05_pull_requests.rst#gen-ai-assisted-contributions).
   
   Generated-by: Codex (GPT-6)


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