jakman85andClaude Opus 5
a795cb8b9a
Agents have been working in the operator's checkout and clobbering each other. Nothing in the tree told them not to: worktrees appeared in CLAUDE.md only as §3's gate workarounds, and decisions/README.md described worktree isolation as something agents already do rather than as a rule. New CLAUDE.md §0 states the rule, with the commands and an explicit do-not list for the shared checkout. Placed before §1 so every existing §-reference in the repo keeps its meaning. Measured in the shared checkout on 2026-10-05, each row a distinct failure mode: 107 `checkout: moving` reflog entries; sitting on feat/pm-agent-issue-to-pr, not main; two other runs' untracked trees left in it; local main two commits behind origin/main; 42 registered worktrees of which 31 are on already-merged branches; 9 gate scripts carrying a `.claude/` exclusion because an in-tree worktree made find-based discovery count the same manifest up to 18 times. Corrects a claim carried in earlier briefs: `git worktree remove` is NOT blocked by the agent sandbox. Provoked on a throwaway worktree — rc 0. §3 reframed as the normal path and grown from two breakages to three: spec-immutability's skip is avoidable, not merely tolerated, with the spec repo mounted read-only in the same ENGINE shim plus -e SPEC_REPO=/home-network-k3s. CLAUDE.md is a sensitive path, so this PR needs a non-author review or an administrator /approve-override posted as a PR review. Not posted by me: §1 forbids an agent clearing that on its own PR. 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.