# REPORT — The removal that works once, and a status page that says what it is asking for (2026-08-13)

**Shipped:** `installer-v1.28.0`, published and verified against the live URL.
**Register:** R-305 CLOSED (by R-316), **R-316 / R-317 / R-318 opened**; ceiling R-315 → **R-318**.
**Venue:** `drill-r50` only. Neither demo box reinstalled. `peti-felhom` not contacted. Nothing deleted.

---

## 1. Cycle 3, before and after

**Before — on the PUBLISHED v1.27.0, from `virgin`, exit 1:**

```
[ERROR]   a resolver is already bound to :53 on this host:
      udp UNCONN 0 0 0.0.0.0:53 … users:(("dnsmasq",pid=7076,fd=4)) …
[ERROR] a resolver is already bound to :53 on this host — Felhom needs the guest reachable by name on your LAN.
  Stop or reconfigure that resolver, OR point your LAN DNS at the guest's address, then re-run.
  (Felhom does NOT touch DNS services on a host it does not own — this is a refusal, not a change.)
  THIS LOOKS LIKE OURS. A previous Felhom install leaves the dnsmasq PACKAGE installed and its unit
  enabled (only our config snippet is removed), and unconstrained it binds 0.0.0.0:53 — which is what
  this gate is seeing. If this host had no dnsmasq before Felhom, clear it with:
      systemctl disable --now dnsmasq
  Then re-run this installer. If dnsmasq is YOURS, leave it and use one of the two routes above.
[ERROR] PRE-FLIGHT FAIL (exit 1) — fix the finding above and re-run
```

**After — v1.28.0, three fresh cycles from `virgin`, exit 0:**

```
:53 now: 0
CYCLE 3 rc=0
[INFO]   host DNS (:53): free
[OK] pre-flight passed
[OK] PRE-FLIGHT PASS (mode=byo) — no state written, no install step executed
```

The three cycles were run on bytes **sha256-identical** to what the live URL now serves
(`cca1dedd9b7c152c…`, compared three ways: live URL, tested file, repo main).

## 2. The mechanism, at `file:line`

| | |
|---|---|
| ownership **recorded** | `felhom-host-install.sh:1718` — preflight, `dpkg-query -W -f='${Status}' dnsmasq \| grep -q "install ok installed"` |
| ownership **read** | `:1097` (`_state_get dnsmasq_preexisting`) at uninstall |
| state file **deleted** | `:1268` — *after* the read. **The order was already correct.** |
| Felhom's dnsmasq snippets removed | `:1162`, in the loop just above the ownership decision |

**Why cycle 2 concludes "pre-existing": package presence alone.** The preflight asks dpkg one question
and nothing else — it does **not** consult the absence of a record, and it cannot, because the record
was deleted with the state file. v1.27.0 stopped the unit and left the package, so the answer stayed
`yes` and our own package became "the household's" one cycle later.

**What the first uninstall did and did not remove:** snippets — removed. Unit — stopped + disabled.
State file (and with it the record) — removed. **Package — left.** That last one is the whole defect.

## 3. What v1.28.0 changes

When the record says we installed it, the uninstall **removes the package** as well as stopping the
unit. Order unchanged: read the record → act → delete the state.

**Two packages are recorded, not one.** `dnsmasq` ships the systemd unit; **`dnsmasq-base` ships
`/usr/sbin/dnsmasq`** (`dpkg -S`, measured on the box). Separately installable, so each is recorded at
preflight and taken back only if we added it.

**Guard rails:** ownership **read, never inferred**; the dependency check is an **`apt-get -s purge`
simulation** that proceeds only if the removal set is a subset of ours, else stop+disable **naming the
blocking package**; never interactive; **never fatal** — a wedged apt is recorded and restated in the
closing NOTE; and the success is **re-queried** rather than read off apt's exit code.

## 4. Scenarios and red-proofs

| Scenario | Result |
|---|---|
| **A** three cycles, fixed | install 3 **PASSES**, `:53` free at every uninstall |
| **B** resolver pre-dates Felhom | **untouched** — `install ok installed`, unit active, both packages recorded `yes` |
| **C** something depends on it | **not purged**; log named `household-dns-thing`; stop+disable; `:53` free; dependent survived |
| **D** no ownership record | **untouched**, reason logged, exact command named |

**Red-proofs — mutation asserted applied before each run:**

| Mutation | Outcome |
|---|---|
| remove the purge call | cycle 2 records `yes`; **cycle 3 refuses, exit 1, in those exact words** |
| remove the ownership check | **the household's resolver is PURGED** (`unknown ok not-installed`) |
| infer ownership when no record | **the guess is taken** — a field box loses its own DNS |

**One honest note on red-proof B.** Its first run appeared to pass *for the wrong reason*: apt failed
with `dpkg was interrupted` (a broken state my own earlier manual package juggling left), so the
resolver survived by accident rather than by the guard. I repaired dpkg and re-ran, and it then failed
as required. Worth stating twice over: the mutation looked like a passing guard, and **my own fix's
apt-failure path was incidentally observed doing exactly what it should** — logging, continuing, naming
the command.

## 5. The machines already in the field

**Measured, not reasoned.** A field box is one with the package installed and **no record** — scenario
D. Its uninstall leaves the resolver running with the reason logged, and its next install refuses with
the message quoted in §1.

**Is there an honest durable marker? No, and none can be invented.** The Felhom `/etc/dnsmasq.d/
felhom-*.conf` snippets are deleted by the uninstall's own loop *before* the ownership decision; the
state file carrying the record is deleted at `:1268`; nothing under `/etc/felhom*` survives.
`/var/log/dpkg.log` does record the install and is a **timestamp** — refused by the standing rule as a
heuristic dressed as a fact. → **R-318**

**The preflight message, judged as a customer would:** it states the finding, keeps its two routes and
its written promise not to touch DNS on a host we do not own, and adds the one thing that gets a person
moving — *"THIS LOOKS LIKE OURS"* plus one exact command. It hedges correctly (*looks like*). Its
weakness is that it asks them *"did this host have dnsmasq before Felhom?"* — precisely the question we
can no longer answer for them. **That is a mechanism, not a rule: the command is on the screen at the
moment it is needed.**

## 6. The defect I nearly shipped

The agent decides whether to install dnsmasq with `os.Stat("/usr/sbin/dnsmasq")`
(`felhom-agent/internal/lanresolver/lanresolver.go:105`) — but that path belongs to **`dnsmasq-base`**,
while the unit comes from **`dnsmasq`**. Purging only `dnsmasq` would leave the binary, so the next
install would skip the apt step and then fail to enable a unit that is gone — **a silent resolver where
today there is at least a visible refusal.** That is why ownership is recorded per package.

It remains reachable where `dnsmasq-base` pre-dated Felhom (we correctly keep it). **Pre-existing, not
introduced here**, filed as **R-317**, and the uninstall now says so out loud rather than leaving it to
be found from a resolver that never came up. Fixing it is a one-line agent change, deliberately **not**
made here to keep this session to one repo.

## 7. Publication

`installer-v1.28.0` tagged; **both** `--ref`s in `manifests/webpage.yaml` moved (sidecar 327, init 372);
ArgoCD synced to `823cd29`; live deployment carries the new ref.

```
live URL serves: SCRIPT_VERSION="1.28.0"       (was 1.27.0)
_dnsmasq_purge_owned present in the served file: 3
```

**Pushing publishes nothing here** — `/scripts/` follows the tag. The runbook still says otherwise;
**R-309 remains open and is not forgotten**, deliberately out of scope.

## 8. Teardown — four layers

| Layer | State |
|---|---|
| **machine** | `drill-r50`: 0 guests, no `/var/lib/felhom-install`, dnsmasq `not-installed` at the end |
| **host** | `drill-r50` **reverted to snapshot `virgin`, powered off**; `qemu.pid` removed. DooPlex was drill host only |
| **hub** | `drill-r50-0a4f9a` **RETAINED** — pre-existing since 2026-07-25, re-used not duplicated. **No new host or customer row was created this session.** Nothing deleted |
| **off-site** | **Not contacted at all** — no restic, sftp or endpoint call was made. `demo-felhom`: `last_status=ok`, `escrow=escrowed`, **no abandon countdown** |

Both demo boxes untouched and healthy: controller **0.214.0**, agent **0.129.0**, `Up … (healthy)`.

## 9. Evidence, and a repeated miss

Logs at `documentation/audits/evidence-r316-2026-08-13/`: the fixed cycles (`F1`, `F2`, `F3`), all four
scenarios (`B`, `C`, `D`), and every red-proof (`RPA*`, `RPB*`, `RPD*`).

**The Part 1 logs did not survive.** They were on the drill VM's disk and were destroyed by the revert
to `virgin` between Part 1 and Part 2 — **the same mistake as Tuesday, in the same place.** The §1
quotation is verbatim from the live run as read at the time, and `RPA1/RPA2/RPA3.log` are an
independent reproduction of the identical three-cycle failure, retained. Recorded rather than glossed;
the fix is procedural and I have now got it wrong twice.

## 10. Observations — noticed, not acted on

- **`dnsmasq-base` is flagged "automatically installed and no longer required"** after `dnsmasq` goes.
  We deliberately do not `autoremove` — that would be a blast radius nobody asked for.
- **`apt-get -s purge` exits 0 even when it prints `E: dpkg was interrupted`.** The simulation output is
  the signal, never the exit code — which is why the guard parses `Remv`/`Purg` lines rather than
  trusting `$?`. Another entry for the exit-codes-that-lie class.
- The drill VM's `pveam` index is stale on `virgin` and needs `pveam update` before listing templates —
  already recorded yesterday, hit again today in passing.
