jakman85andClaude Opus 5
fda5c31a94
Operator reported DNS flapping between the cluster ingress and the router's public IP. PiHole is not at fault -- both replicas answer 192.168.2.20 consistently (6/6 via the VIP, 8/8 from a client). The bug is an asymmetry in CACHEABILITY that we created. Measured: pihole 192.168.2.23 -> 192.168.2.20 TTL=0 public 1.1.1.1 -> wan.home.keithjackson.dev TTL=300 router 192.168.2.1 -> wan.... TTL=153 -> 148 -> 143 (decrementing = caching) dnsmasq answers `address=` entries with TTL 0 unless told otherwise. The router forwards LAN queries to PiHole and caches the result, so the CORRECT answer is uncacheable -- re-queried on every lookup, maximum exposure to any gap -- while the WRONG answer caches for 300s. The instant the router falls back to upstream (standard forwarder behaviour when the target does not answer) it latches the WAN address for the whole LAN for five minutes, then expires, re-queries PiHole, gets TTL 0, and is immediately re-exposed. So ONE sub-second PiHole gap -- pod restart, L2 lease move, ARP flap, kured reboot -- becomes FIVE MINUTES of the house resolving to the WAN IP. That asymmetry, not the gap, is why it reads as "flapping". Fix: local-ttl=60 prepended to FTLCONF_misc_dnsmasq_lines. dnsmasq applies local-ttl to replies made from configuration, so one directive covers all five address= names. 60s rides out a pod restart and a lease re-election while a real VIP change still propagates inside a minute; these VIPs are pinned and static. apps/wave-0/pihole.yaml regenerated with the canonical render command (--all catalog -o apps --wave-layout --no-image-automation, NOT --emit-waves); exactly two files changed and the rendered diff is the single local-ttl prefix. UNAPPLIED. Does NOT remove the trigger: .23 still has two independently-elected L2 leases (as do crafty .22 and unifi .21), which the operator has parked. If the TTL is still 0 after merge, suspect FTL silently rejecting the passthrough line -- see the handoff. Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
decisions/ — the handoff log, one file per entry
This directory is the decision log. ../DECISIONS-LOG.md is the frozen archive of
everything written before 2026-09-29 and is never edited again (see "The archive is
frozen" below).
Why this exists
DECISIONS-LOG.md was append-only in a single file, and every agent appended to its
tail. Two branches that both append hit the same last hunk, so git cannot
auto-merge them: the second one to be reviewed conflicts, and so does the third, and
the fourth. Measured on 2026-09-29: four of the five open PRs were unmergeable, and
DECISIONS-LOG.md was the only conflicting file in all four:
#22 fix/crafty-oauth2-proxy-signin CONFLICT (content): DECISIONS-LOG.md
#20 feat/conformance-job-template CONFLICT (content): DECISIONS-LOG.md
#19 feat/conformance-trigger-kubeconfig CONFLICT (content): DECISIONS-LOG.md
#18 feat/conformance-runner-image CONFLICT (content): DECISIONS-LOG.md
#17 feat/ci-is-the-approver clean (it touched no log entry)
Nothing was wrong with any of those changes. The log's storage format serialised work that was otherwise parallel, and it got worse with every concurrent branch: N branches produce N-1 rebases, each of which invalidates any gate run that preceded it.
The fix is the obvious one for concurrent appenders: stop sharing a file. Each
handoff is its own file. Two agents writing handoffs touch disjoint paths, so there is
nothing for git to merge and nothing to conflict. This scales to any number of parallel
branches with zero coordination — which is the point, since the agents are deliberately
isolated from each other in separate worktrees (required by CLAUDE.md §0) and cannot
coordinate.
There is deliberately no index file and no counter. An index would be a shared
mutable file — exactly the thing that just failed — and a sequence number would have
two agents racing for 0043. The directory listing is the index.
Writing an entry
One file per handoff, named:
decisions/YYYY-MM-DD-<slug>.md
<slug> is lowercase [a-z0-9-]. Use your branch name's last segment — it is
already unique per unit of work, which is precisely the property the filename needs.
A branch fix/crafty-oauth2-proxy-signin handed off on 2026-09-29 writes:
decisions/2026-09-29-crafty-oauth2-proxy-signin.md
The file is YAML frontmatter followed by three required sections:
---
date: 2026-09-29
branch: fix/crafty-oauth2-proxy-signin
title: The Keycloak gate works — Crafty's own login was the wall
---
## What changed
Prose. What you actually did, and why.
## What I verified
The measurements, with their numbers. Quote the field you read, not the prose you
believed. Name the gate result and its exit code.
## What I did NOT verify
Everything else. An honest "UNVERIFIED" is worth more than an optimistic "green" —
this repo has been burned by the difference more than once.
All three headings are required and enforced (ci/decisions-log.sh). They are
CLAUDE.md §7's contract; making them a checked structure is what stops an entry
degrading into "done ✅".
Reading the log
The whole log, oldest first:
ls decisions/[0-9]*.md | sort
The current PM handoff — the newest entry. Ties within a day are broken by what landed
on main last, which is the honest answer, so ask git rather than the filename:
git log --diff-filter=A --format='%H' --name-only -- 'decisions/[0-9]*.md' \
| grep '^decisions/' | head -1
For a quick skim of who said what:
grep -H '^title:' decisions/[0-9]*.md | sort
The archive is frozen
DECISIONS-LOG.md is read-only history. Its SHA-256 is pinned in
decisions/ARCHIVE.sha256 and ci/decisions-log.sh fails the merge gate if the file
changes. That is not ceremony: without it, the next agent to read runbooks/ or an old
CLAUDE.md habit appends to the tail again and re-creates the conflict for everybody
else, silently, one PR at a time.
If the archive genuinely must change (a leaked credential to redact, say), that is a
deliberate, reviewed act: change it, run sha256sum DECISIONS-LOG.md > decisions/ARCHIVE.sha256,
and say in your handoff entry why. Re-pinning is visible in the diff. Appending is not.