fix(loop): worktree provisioning, fresh fetch, corruption halt

Three P1 adoption-wave findings, all of which break an unattended run.
The worktree needs make build-frontend and make testdata once before its
first push — the pre-push go-test hook embeds frontend/dist and the
fixture library and refused the push without them. The merge leg now
says to fetch origin/main in the same breath as the refresh merge: a
cached origin/main merged against the wrong base, CI went green on it,
and the merge came back 405 "behind base" — a full cycle wasted. And a
killed fetch leaves 0-byte objects in the shared store whose signature
(error: object file … is empty / unpack-objects failed) must halt the
loop for a human instead of churning, with the repair recipe written
down.

Closes #240

.pi/skills/yj-loop/SKILL.md

@@ -168,8 +168,12 @@ Merge when, and only when, **all** hold:
   `block_on_outdated_branch: true` refuses it anyway; never
   `force_manually_merged` around it.
 
-**Refresh before every merge.** In the loop worktree: fetch, then
-`git merge origin/main` on the PR branch, push. A textual conflict
+**Refresh before every merge.** In the loop worktree: `git fetch origin`
+in the same breath, then `git merge origin/main` on the PR branch,
+push. The fetch must be immediate — a cached `origin/main` merges
+against the wrong base, CI goes green on it, and the merge comes back
+405 "behind base", one whole CI cycle wasted (measured on the adoption
+wave). A textual conflict
 stops the leg there — as diff text, not as a failed merge click: hunks
 the loop authored are resolved by the loop; anything else is left with
 `⟦loop⟧` comment for a human, never forced. After any refresh push,
@@ -247,7 +251,10 @@ AVD), then `make android-emulator` per session.
 
 - **Worktree:** `git worktree add ~/.paseo/worktrees/loop/jumpy-hound
   origin/main` (from any clone; branch from origin/main in the loop
-  tree, never `git checkout main`).
+  tree, never `git checkout main`). **Provision it once before the
+  first push:** `make build-frontend` and `make testdata` — the pre-push
+  `go-test` hook needs `frontend/dist` (the `//go:embed` in `main.go`)
+  and the fixture library, and refuses the push without them.
 - **Session:** pi in that worktree, `/name loop`. Add the job via
   `/schedule-prompt` (name `yj-loop`, cron
   `0 0 10-18 * * 1-5`, prompt: "Read `.pi/skills/yj-loop/SKILL.md` and
@@ -270,4 +277,12 @@ AVD), then `make android-emulator` per session.
   which leg it really is.
 - The job did not fire — the scheduler fires only while a session is
   open in its directory (documented); "the loop is off" is the correct
-  reading, not a bug.
+  reading, not a bug.
+- `error: object file … is empty` / `unpack-objects failed` / `bad
+  object refs/heads/…` during a fetch or checkout — the shared object
+  store was corrupted (a killed fetch leaves 0-byte object files, and a
+  local ref can end up pointing at the dead sha1). **Halt and report**;
+  do not retry, the churn only deepens it. Human repair: delete the
+  0-byte objects, `git fetch origin --prune`, delete any ref that
+  still dangles (`git update-ref -d refs/heads/<b>`), re-checkout the
+  worktree at `origin/main`, then `git fsck --full`.

.planning/plans/active/020-autonomous-backlog-loop.md

@@ -112,7 +112,9 @@ in the job's directory — that limitation is the switch:
 
 - **Worktree:** `git worktree add` a dedicated clone at
   `~/.paseo/worktrees/loop/jumpy-hound`. Loop edits happen only there; a
-  dirty tree there is the loop's business and nobody else's.
+  dirty tree there is the loop's business and nobody else's. **Provision
+  it once before its first push:** `make build-frontend` + `make testdata`
+  — the pre-push `go-test` hook needs both and refuses without them.
 - **Session:** pi in that worktree, `/name loop`. The job is bound to that
   session, so another pi elsewhere in the same directory does not
   double-fire it.

CLAUDE.md

@@ -172,7 +172,7 @@ make ui-test          # Vitest component/store suite in a real browser (no app)
 make ui-visual        # Same, including toMatchScreenshot comparisons
 make ui-setup         # Install the Vitest provider's own Chromium (once)
 make bindings-check   # Fail if frontend/bindings is stale vs the Go bindings
-make skill-check      # Fail if .pi/ documents a make target that doesn't exist
+make skill-check      # Fail if a doc names a make target that doesn't exist
 make commit-check     # Fail if a commit subject is not a Conventional Commit
 make lint             # golangci-lint v2 (strict), all three build configurations
 make test             # All tests with race detector, all three build configurations

Makefile

@@ -192,7 +192,7 @@ css-check: ## Fail on a css`` literal ended early by a backtick, or a nested rul
 # Every command in them is a make target on purpose, so this is
 # checkable.  It also asserts AGENTS.md is a symlink to CLAUDE.md, so the
 # two harnesses cannot drift onto two descriptions of one project.
-skill-check: ## Fail if the agent docs name a missing make target, or AGENTS.md is not a symlink
+skill-check: ## Fail if the docs name a missing make target, or AGENTS.md is not a symlink
 	@./scripts/skill-check.sh
 
 # Conventional Commits, which CLAUDE.md claimed CI enforced for a long

lefthook.yml

@@ -38,10 +38,14 @@ pre-commit:
       glob: "*.go"
       run: ./scripts/bindings-check.sh
 
-    # .pi/ documents make targets; a stale one sends an agent off a
-    # cliff with total confidence.  Instant.
+    # The docs document make targets; a stale one sends an agent — or a
+    # contributor reading CONTRIBUTING.md — off a cliff with total
+    # confidence.  The glob is the script's own scanned set, because a
+    # hook that does not fire on a file the check reads is the drift the
+    # check exists to prevent: it was `{Makefile,.pi/**/*.md}` while the
+    # script already read CLAUDE.md.  Instant.
     skill-check:
-      glob: "{Makefile,.pi/**/*.md}"
+      glob: "{Makefile,.pi/**/*.md,AGENTS.md,CLAUDE.md,README.md,CONTRIBUTING.md}"
       run: ./scripts/skill-check.sh
 
     frontend-typecheck:

scripts/skill-check.sh

@@ -14,6 +14,11 @@
 # missing: CLAUDE.md names 27 targets and nothing verified one of them,
 # so the file the agents trust most was the file least checked.
 #
+# README.md and CONTRIBUTING.md are in it too, and the header sentence
+# above is why: a person who has *not* read the Makefile goes looking in
+# the contributor-facing doc, so a renamed target sends them off the
+# same cliff it sends an agent off.  CONTRIBUTING.md names 21 targets.
+#
 # **AGENTS.md is a symlink to CLAUDE.md.**  This repo is worked on by
 # two agent harnesses that read different files by convention — Claude
 # Code reads CLAUDE.md, others read AGENTS.md — and two harnesses
@@ -43,7 +48,19 @@ if [ -e AGENTS.md ] || [ -L AGENTS.md ]; then
 	fi
 fi
 
-[ -d .pi ] || exit 0
+# The scan is over the docs that are actually there: a checkout without
+# .pi/ still has README.md and CONTRIBUTING.md to check, and gating the
+# whole run on .pi/ would have made the human-facing half conditional on
+# the agent-facing one.  This list is used twice — once to read the
+# mentions out and once to say which file a missing target came from —
+# because a second list is a second thing to forget.
+# `ls` exits non-zero when *any* of its arguments is missing while still
+# printing the ones that are there, and under `set -e` that would sink
+# the assignment rather than scanning what exists, so swallow it.
+docs="$({ find .pi -name '*.md' 2>/dev/null
+	ls CLAUDE.md README.md CONTRIBUTING.md 2>/dev/null || true; })"
+
+[ -n "$docs" ] || exit 0
 
 # `make -pq` prints the database including every rule, without running
 # anything.  It exits non-zero when a target is out of date, and under
@@ -68,7 +85,7 @@ targets="$({ make -pqRr 2>/dev/null || true; } |
 # AGENTS.md is deliberately not in this list: it is a symlink to
 # CLAUDE.md, asserted above, so scanning it would report every failure
 # twice under two names.
-mentioned="$({ find .pi -name '*.md' 2>/dev/null; echo CLAUDE.md; } |
+mentioned="$(printf '%s\n' "$docs" |
 	xargs awk '
 		FNR == 1 { fence = 0 }
 		/^```/   { fence = !fence; next }
@@ -93,10 +110,10 @@ for t in $mentioned; do
 done
 
 if [ -n "$missing" ]; then
-	echo "skill-check: the agent docs name make targets that do not exist:" >&2
+	echo "skill-check: the docs name make targets that do not exist:" >&2
 	for t in $missing; do
 		echo "  make $t" >&2
-		grep -rln "make $t" .pi CLAUDE.md --include='*.md' | sed 's/^/      /' >&2
+		printf '%s\n' "$docs" | xargs grep -ln "make $t" | sed 's/^/      /' >&2
 	done
 	echo "Fix the docs, or restore the target." >&2
 	exit 1