The pull-request bar

What a PR must clear, in order:

1. Builds clean: make kernel with -Wall -Wextra -Werror - on your machine and on CI (CI's toolchain is often stricter; the multiboot2 packed-cast and rdrand setc fixes exist precisely because a stricter GCC/GAS on the runner caught what local builds accepted).
2. Host tests: make test - zero failures.
3. Boots: make run-bios and make run-uefi - both reach the oc> prompt with boot complete ... OK.
4. The deep test for whatever you touched - the matrix in CONTRIBUTING.md (storage -> fstest; crypto -> cryptotest + HTTPS E2E; watchdog/klog/health -> the WP-12 E2E; boot path -> the 28-check regression).
5. Reproducible: make reproducible-check prints PASS.
6. Docs in the same PR: new command -> its reference page is generated (make api-docs refreshes docs/manual/commands/ and INTERFACES.md); new interface -> the surface tables; behaviour change -> the matching manual page.
7. CI green: the workflow runs build, ISO, packages, host tests and the reproducibility gate on every PR - merge only on green.

Writing the PR description

• What changed and why - the commit messages carry the detail.
• Which tests you ran (commands + result lines, pasted).
• Anything you deliberately did NOT do (scope edges).

Review expectations

Expect questions about error paths, DMA bounds, and what happens when the hardware lies (a truncated table, a stuck NAK, a card that answers garbage). The tree's own history - BUG-0136..0238 - is a catalogue of exactly these; reading a few of those fix commits is the best preparation.