B2: root-cause fixes for red nightlies on main #4715

Parent for B2 (no check red on main >24h), 0.70.2 epic #4678. P0, K̂ 3. Proposed by aprender-a7, minted by cop aprender-14. One checklist line per root-cause fix PR from aprender-wmainred:

• fix(mutants-nightly): read workspace-test excludes from ci/sections.yml (red since #4655) #4705 fix(mutants-nightly): read workspace-test excludes from ci/sections.yml (red since fold(0.70): #4587+#4588 PMAT-4502, #4620 #3715, #4614 #4616, #4640 PMAT-937 (C221 fat_driver fix) #4655)

• fix(nightly): darwin leg built into the mini's redirected target dir (exit 127) #4706 fix(nightly): darwin leg built into the mini's redirected target dir (exit 127)

• fix(nightly): publish paginates release assets (117 staged leftovers past page 1 → 422) #4707 fix(nightly): publish paginates release assets (117 staged leftovers past page 1 → 422)

• fix(ci): conleche-nightly cache path is lambda-only — mkdir denied on clean-room #4708 fix(ci): conleche-nightly cache path is lambda-only — mkdir denied on clean-room

• fix(ci): CUDA Nightly G0 step aborted on its own RED control (bash -e) #4713 fix(ci): CUDA Nightly G0 step aborted on its own RED control (bash -e)

• fix(guard): tree-reader 2018 layout, Toolchain Ceiling clippy 1.99, publish preflight R8 SIGPIPE (guards-nightly BSE-17) #4716 fix(contracts): json.rs -> json/mod.rs so the tree-reader guard resolves json/github.rs (guards-nightly BSE-17)

• fix(ceiling): current-stable clippy findings that turned Toolchain Ceiling red #4724 Toolchain Ceiling (wmainred, armed)

• fix(qwen-story): pmat hunt reads coverage-nightly's file iff same sha, else not_measured (#4715) #4726 fix(qwen-story): pmat hunt reads coverage-nightly's file iff same sha, else not_measured (B2: root-cause fixes for red nightlies on main #4715)

• Renew repo secret INFRA_ACTIONS_READ (paiml/infra, Actions: read, 90-day expiry) before 2027-01-02. Operator act. Without it, release-lanes-nightly cleanroom-cpu reads not_measured (0702-P3: nightly producers for the cleanroom-cpu/gpu, assets and publish-dryrun lanes #4720, feat(release): nightly producers for cleanroom-gpu, cleanroom-cpu, publish-dryrun (#4720) #4725)

• T30 branch fix/sourced-libs-option-neutral-scripts-lib @ 04b6820: check_sourced_libs_option_neutral.sh widened to scripts/lib (8 sourced libs, 0 leaks; ratchet floor 8). Branch only, no PR until the freeze lifts (wmainred)

Folded sub-tickets (TRIAGE-100, 2026-10-14)

These open sub-tickets were folded here as checklist rows and closed as not planned so the open count stays at or under 100. Reopen one when its work resumes; an open PR for it reopens it.

• mutants-nightly interim ARM64 pool: x86_64-only mutants NOT_MEASURED; bound the window after a timeout #4858 — mutants-nightly interim ARM64 pool: x86_64-only mutants NOT_MEASURED; bound the window after a timeout
• ci: mutants-cuda never runs its scope ("Failed to connect to bus", no measured.txt) #4895 — ci: mutants-cuda never runs its scope ("Failed to connect to bus", no measured.txt)
• deep_nodefault_verdict: OOM-killed rustc beside #3176 errors, duplicate rows, empty row name #4922 — deep_nodefault_verdict: OOM-killed rustc beside aprender-distribute uses tokio unconditionally behind an optional feature: --no-default-features has 44 errors, and no gate has ever run it #3176 errors, duplicate rows, empty row name
• LAB: beat-speed nightly red, GaussianNB ratio 0.503 over the 0.50 ceiling (1 red after 3 green) #4965 — LAB: beat-speed nightly red, GaussianNB ratio 0.503 over the 0.50 ceiling (1 red after 3 green) (branch: la-711b/4965-gnb-predict)
• LAB: provable-ladder-nightly red on main nightly (run 38006983885) #5009 — LAB: provable-ladder-nightly red on main nightly (run 38006983885)
• LAB: CUDA Nightly (GPU QLoRA falsifiers) red on main nightly (run 38008296149) #5011 — LAB: CUDA Nightly (GPU QLoRA falsifiers) red on main nightly (run 38008296149) (branch: PMAT-5011-gb10-beat-floor)
• LAB: conleche-nightly red on main nightly (run 38011337533) #5014 — LAB: conleche-nightly red on main nightly (run 38011337533) (branch: fix/5014-conleche-sysroot)
• cuda-nightly cuda-check label path runs a LAB lane in a PR job and a yield night reads green #5030 — cuda-nightly cuda-check label path runs a LAB lane in a PR job and a yield night reads green (branch: PMAT-5030-cuda-nightly-lab-only)
• assets-rehearsal nightly: not green #5041 — assets-rehearsal nightly: not green
• Models nightly crux producer failed with an exit-code at its 23:00 CEST start #5098 — Models nightly crux producer failed with an exit-code at its 23:00 CEST start
• Models nightly publish producer refused with exit 3: a registry token is reachable #5100 — Models nightly publish producer refused with exit 3: a registry token is reachable
• LAB: nightly train lane deep-bins-smoke (off the release verdict) #5148 — LAB: nightly train lane deep-bins-smoke (off the release verdict)
• LAB: nightly train lane dogfood (off the release verdict) #5149 — LAB: nightly train lane dogfood (off the release verdict)
• LAB: nightly train lane readiness (off the release verdict) #5150 — LAB: nightly train lane readiness (off the release verdict)
• LAB: nightly train lane cleanroom-cpu (off the release verdict) #5151 — LAB: nightly train lane cleanroom-cpu (off the release verdict)
• LAB: nightly train lane publish-dryrun (off the release verdict) #5153 — LAB: nightly train lane publish-dryrun (off the release verdict)
• LAB: build-sha stamp uses --short with no length; the release check wants exactly 9 #5196 — LAB: build-sha stamp uses --short with no length; the release check wants exactly 9 (branch: w71-e3a/5196-build-sha-short9)
• LAB: CRUX harness runs llama-cli under a controlling tty — 0-byte output with rc 0 #5197 — LAB: CRUX harness runs llama-cli under a controlling tty — 0-byte output with rc 0
• LAB: dogfood-nightly has never been green (run 38155045677) #5199 — LAB: dogfood-nightly has never been green (run 38155045677) (branch: fix/5199-dogfood-nightly-reds)
• LAB: aprender-test-lib tests shell out to curl and kill #5200 — LAB: aprender-test-lib tests shell out to curl and kill (branch: la-711b/5200-no-external-tools)
• LAB nightly ratchet comparand: refuse when base == HEAD; idle main must not fail the fetch #5204 — LAB nightly ratchet comparand: refuse when base == HEAD; idle main must not fail the fetch — done when: a case table row for each of the two (idle main with nothing in the window; base == HEAD), RED before and GREEN after.