fix(prune): stop protecting publisher target dirs under disk pressure

Conversation 1 Commits 1 Files Changed 4

+106 -38

1 Commits

Author	SHA1	Message	Date
claudeandClaude Sonnet 5	dc473f0d0c	fix(prune): stop protecting publisher target dirs under disk pressure CI / shellcheck + selftests (pull_request) Successful in 1m48s Details A publisher branch's target-<ref> was protected identically to its snapshot-<ref>, so it was never a pressure-pass candidate however old and however tight the disk. With one branch's target dir permanently resident alongside its snapshot, a second branch had no room to seed, and every PR that night needed a hand eviction between runs (daniel/gitdan-actions#24). A publisher's target dir is a convenience cache its own next run reseeds from the snapshot, so losing it under pressure is cheap; nothing downstream depends on it surviving. Only the snapshot stays protected in the pressure and self-clear passes. Unprotecting the target dir outright surfaced a second bug the fix would otherwise have shipped: a branch's tip is trivially an ancestor of itself, so once a protected ref's target dir was no longer skipped before reaching the merged-branch check, pass 1 read it as "merged into itself" and deleted it unconditionally on every run, independent of disk pressure. is_protected_from_liveness keeps a protected ref's target dir out of pass 1 alone, so it stays an ordinary pressure-pass candidate without ever reaching that check. Scenario 3b in the selftest red-proves this against the unprotect-only version of the fix. Also corrects the header's inode-sharing claim, measured false on the live volume by daniel/zemyna#1073: publish-snapshot.sh unshares every executable after its cp -al, and executables are most of the tree by bytes, so a snapshot eviction is a real, large disk cost rather than the near-free one the old text described — the target-before-snapshot ordering still holds, now for the warm-start reason alone plus that cost. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01UkSjXXtU6JYcN2vPntWhfb	2026-09-22 10:42:08 -05:00

Author

SHA1

Message

Date

claudeandClaude Sonnet 5

dc473f0d0c

fix(prune): stop protecting publisher target dirs under disk pressure

CI / shellcheck + selftests (pull_request) Successful in 1m48s

Details

A publisher branch's target-<ref> was protected identically to its
snapshot-<ref>, so it was never a pressure-pass candidate however old
and however tight the disk. With one branch's target dir permanently
resident alongside its snapshot, a second branch had no room to seed,
and every PR that night needed a hand eviction between runs
(daniel/gitdan-actions#24).

A publisher's target dir is a convenience cache its own next run
reseeds from the snapshot, so losing it under pressure is cheap;
nothing downstream depends on it surviving. Only the snapshot stays
protected in the pressure and self-clear passes.

Unprotecting the target dir outright surfaced a second bug the fix
would otherwise have shipped: a branch's tip is trivially an ancestor
of itself, so once a protected ref's target dir was no longer skipped
before reaching the merged-branch check, pass 1 read it as "merged
into itself" and deleted it unconditionally on every run, independent
of disk pressure. is_protected_from_liveness keeps a protected ref's
target dir out of pass 1 alone, so it stays an ordinary pressure-pass
candidate without ever reaching that check. Scenario 3b in the
selftest red-proves this against the unprotect-only version of the
fix.

Also corrects the header's inode-sharing claim, measured false on the
live volume by daniel/zemyna#1073: publish-snapshot.sh unshares every
executable after its cp -al, and executables are most of the tree by
bytes, so a snapshot eviction is a real, large disk cost rather than
the near-free one the old text described — the target-before-snapshot
ordering still holds, now for the warm-start reason alone plus that
cost.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UkSjXXtU6JYcN2vPntWhfb

2026-09-22 10:42:08 -05:00

fix(prune): stop protecting publisher target dirs under disk pressure #25