docs: CLAUDE.md becomes a core plus path-scoped rules (R-229)

215 lines -> 110 (92 effective; block-level HTML comments are stripped before
injection and never reach the model, verified empirically on Claude Code 2.1.222
with a control and a treatment run).

Four new .claude/rules/*.md, each with a paths: glob list so it loads only when a
matching file is read: gates, ui-hungarian, backup-paths, agent-coupling.

The ## Layout tree was deleted as derivable; REUSE.md already owns the per-package
seams its annotations stood in for. The host/access table was deleted in favour of
a pointer to documentation/operations/nodes.md -- it carried three defects at once:
demo-felhom given as the LAN fallback address as if it were the route, a pinned
"agent 0.93.0" against the project's own no-versions-in-docs rule, and the claim
that no drill VM was provisioned on demo-hp. Measured live: qm list shows VM 300
drill-r50. felhom-agent/CLAUDE.md was right; this file was wrong.

Kept verbatim: the seven session-critical invariants, the F9 live-validation fence,
the end-of-session checklist.

controller_gates.py registers the shared instructions gate (felhom.eu/scripts/,
never copied here; an absent sibling clone FAILS).

Docs only -- no Go, no version bump, no image, no deploy.
Ledger: felhom.eu/documentation/audits/LEDGER-instruction-trim-2026-08-06.md

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JJc8sAGRWmavP3rMtdpkr2

.claude/rules/backup-paths.md

@@ -0,0 +1,41 @@
+---
+paths: ["controller/internal/backup/**", "controller/internal/appbackup/**", "controller/internal/recovery/**", "controller/internal/appexport/**", "controller/internal/quiesce/**"]
+---
+
+# Backup, recovery units and export — felhom-controller
+
+## Assert the consequence across the whole run, not the mechanism inside one function
+
+The R-181 recovery-unit refusal claimed *"the previous unit is untouched and NOTHING was deleted"*.
+*Nothing deleted* held; **untouched was measured false** — the floor was checked ONLY in
+`captureAllRecoveryUnits`, while the two dump legs wrote the bulk into the same tree first and
+unguarded, so a 182,272 B tar became 2,147,666,432 B under a manifest that had not moved. A full
+green suite plus three of its own red-proofs missed it, because every one asserted the mechanism
+inside `captureAllRecoveryUnits`.
+
+**The test that catches this class: fingerprint the tree before and after the whole backup run, and
+compare.** Full doctrine and the other eight instances: the `felhom-testing` skill.
+
+## Presence is not success
+
+A timestamp recording an **attempt** must never be read as evidence of a **result**. Where a status
+field travels alongside a timestamp, the verdict consults both — or the timestamp records only
+successes. Ask of any timestamp: *what exactly must have happened for this to be set?* If the answer
+is "we tried", it cannot answer "did it work".
+
+**Corollary:** when a verdict changes which field it counts from, the alarm text has to change with
+it. `last run 8h ago` while alarming on a six-day-old success turns a true alarm into one the
+operator dismisses.
+
+<!--
+Two instances. F-CRIT-2: a phantom snapshot's ctime set tier freshness — an aborted 1-byte upload
+made the tier look backed up. R-100: LastRun is written on failure, so a nightly-failing offsite
+tier kept the staleness clock fresh forever.
+-->
+
+## Storage keys and paths
+
+- Never guess a persisted key — it is `offbox`, not `offbox_target` (R-7b).
+- `.fab` export/import uses strict segment validation; bundles from controller ≤0.124.0 are hollow.
+- Recovery-unit restore and tier-2 copies share `appbackup`'s path primitives — change them there,
+  once, not per caller.