Adds .github/workflows/README.md: a plain-English walkthrough of the traffic-control job in ci.yml for developers new to the repo — why it exists, how effective priority is computed (P0-P9, default P5, broken => 10), preemption vs. bounded hold-back, the hard safety invariants, and the honest FIFO-runner limitation.
Notes that #342 will refactor this logic into a tested .github/scripts/traffic_control.py module with minor refinements (drafts also => bottom priority, explicit same-level ordering), and that this README will be updated then.
Docs-only change; no code/build/test surface affected.
Verified the doc's claims line by line against the traffic-control job and its comment block in .github/workflows/ci.yml (labels/priority math, preemption conditions, hold-back budget/poll constants, safety invariants, continue-on-error/needs gating behavior).
Matched the repo's Markdown SPDX convention (<!-- SPDX-License-Identifier: GPL-3.0-or-later --> as the first line).
## Summary
- Adds `.github/workflows/README.md`: a plain-English walkthrough of the `traffic-control` job in `ci.yml` for developers new to the repo — why it exists, how effective priority is computed (`P0`-`P9`, default `P5`, `broken` => 10), preemption vs. bounded hold-back, the hard safety invariants, and the honest FIFO-runner limitation.
- Notes that #342 will refactor this logic into a tested `.github/scripts/traffic_control.py` module with minor refinements (drafts also => bottom priority, explicit same-level ordering), and that this README will be updated then.
- Docs only — no workflow behavior changes.
Closes #343
## Test plan
- [x] Docs-only change; no code/build/test surface affected.
- [x] Verified the doc's claims line by line against the `traffic-control` job and its comment block in `.github/workflows/ci.yml` (labels/priority math, preemption conditions, hold-back budget/poll constants, safety invariants, `continue-on-error`/`needs` gating behavior).
- [x] Matched the repo's Markdown SPDX convention (`<!-- SPDX-License-Identifier: GPL-3.0-or-later -->` as the first line).
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Summary
.github/workflows/README.md: a plain-English walkthrough of thetraffic-controljob inci.ymlfor developers new to the repo — why it exists, how effective priority is computed (P0-P9, defaultP5,broken=> 10), preemption vs. bounded hold-back, the hard safety invariants, and the honest FIFO-runner limitation..github/scripts/traffic_control.pymodule with minor refinements (drafts also => bottom priority, explicit same-level ordering), and that this README will be updated then.Closes #343
Test plan
traffic-controljob and its comment block in.github/workflows/ci.yml(labels/priority math, preemption conditions, hold-back budget/poll constants, safety invariants,continue-on-error/needsgating behavior).<!-- SPDX-License-Identifier: GPL-3.0-or-later -->as the first line).🤖 Generated with Claude Code