# REPORT — SPIKE R-117: a dead bind that reports healthy (2026-07-30)

Written as `REPORT-<topic>.md`, not `REPORT.md`, per this repo's parallel-session rule and the
established local pattern (`REPORT-r116-diag.md`, `REPORT-session-c.md`, …). The shared `REPORT.md`
was not touched.

**Class: Spike.** Deliverable is a findings document. **No production code was written; no `.go` file
in either repo was modified; nothing was built for deployment, published, or version-bumped.**

## Deliverables

| File | Action |
|---|---|
| `documentation/audits/SPIKE-r117-bind-liveness-2026-07-30.md` | **new** — the findings doc (Q1–Q7, evidence, recipe, probe comparison, recommendation) |
| `documentation/backlog/OPEN-ITEMS.md` | **R-117 row rewritten** with the mechanism, the reproduction recipe and the fix constraint — the one register edit, per the brief |

**No CHANGELOG entry.** This repo's changelogs are per-area (`hub/`, `scripts/`, `website/`); a
documentation-only change belongs to none of them. Stated rather than silently skipped, per standing
rule 4.

## Baselines

agent `main` **v0.116.0** @ `d4eb259` · controller `main` **v0.186.0** @ `b331f18` ·
`felhom.eu` HEAD `29bcfeb` · hub **live 0.82.0** · golden **0.186.0** ·
demo-hp PVE 9.2.2 / kernel 7.0.2-6-pve, **live agent 0.113.0** (= manifest `MinAgent`; never used as
the source of a behavioural claim — every predicate result came from a probe built from `main`).

## Results

All seven questions answered empirically except the hang case (below).

- **Q1 — reproduced 3/3**, two device classes, on a purpose-built scratch LXC (9301) on demo-hp.
  **The device-node change is a consequence of the defect, not a precondition** — control test: with
  the stale bind held the drive returns as `sdc` (8:32); released, the letter is reused (`sdb`, 8:16).
- **Q2 — two death states**: device removed ⇒ superopts gain `shutdown`, `EIO`(5) on read and write,
  host and guest; device errors in place ⇒ `emergency_ro`, write `EROFS`(30), reads served from cache.
  The raw host mount is genuinely healthy in both. **No cross-device mis-identification is possible**
  on this path — the unit is fs-UUID-keyed.
- **Q3 — confirmed at source and live.** Both halves of the R-113 conjunction compare **field 5** of a
  mountinfo line and **never read field 3 (`major:minor`)**, so neither can see that the bind and the
  raw mount name different devices. Measured `BoundUnderParent = TRUE` over an `EIO` namespace.
- **Q4 — a pure-`/proc` check costs 0.17–0.45 ms**, cannot hang, spins up no disk, writes nothing.
  **`statfs` and `getdents` both SUCCEED on a dead namespace** — probes built on either are hollow.
- **Q5 — the agent**, and not on balance: the controller runs inside the guest and cannot see the host
  mount tables the check needs.
- **Q6 — recovery works in place, guest never restarted** (init PID identical). **The repair code
  already exists and three call sites already invoke it**, including the controller's `Return` branch
  *before* it restarts apps — all defeated by one early return.
- **Q7 — a bind can die in steady state, no cycle at all.** The gate produces no action and **nothing
  is emitted on any channel.** A `Return`-branch fix cannot reach this half.

## Not established

**The hang case (findings §6.3).** The venue (`dmsetup suspend --noflush`) and the two blocking probes
(write+`fsync`, cache-dropped read, both with timeout-fires and thread-leak reporting) were built; the
run did not happen — the venue lost internet mid-transfer of the rebuilt binary. **The associated
thread-leak hypothesis is explicitly not claimed as a result.** It does not gate the `/proc`
recommendation but does gate adding any I/O confirmation probe.

## Teardown — OWED

**Not performed** — the second site outage began first. Findings §14 lists the exact commands. Nothing
fenced was touched at any point (9201 `running`, `drill-r50` `stopped`, `local-lvm` untouched,
`felhom-backup` not re-targeted, `/mnt/felhom-drives` untouched, ep0 read-only). **Layer 3 is
genuinely empty** — guest 9301 had no network interface and ran no controller, so no hub-side record
was created.

## Findings filed, none fixed

R-117 (mechanism + recipe), **R-117a** steady-state death with no event (HIGH, larger than R-117 as
filed), **R-117b** `statfs`/`getdents` are hollow liveness probes, **R-117c** three untested comments
promising "live + usable in the guest", **R-117d** the self-heal that already exists is short-circuited
(HIGH), **R-117e** both demo boxes share one failure domain — no route survives the site losing
internet, including the WireGuard OOB path.