TEL-05 review follow-ups: show unchanged_s, name a timeout, keep the poll task alive

Four follow-ups on the reviewed and approved TEL-05 work. Additive; no shipped
behaviour changes except the two failure paths below.

1. unchanged_s had no operator surface. DOCS.md told a reader "the transport
   tracks it as unchanged_s" and there was nowhere to look: main.py built the
   transport, scheduled run(), and never read the object again. The status page
   now shows it on the healthy P1 line. Still NOT thresholded and NOT folded
   into the age - that refusal was reviewed and upheld, because at the converged
   -10 W this controller aims for a 1 Wh register needs ~6 minutes to move, so
   any limit false-trips at the target operating point. The whole argument for
   leaving it to a human requires the human being able to see it.

2. The "equivalent mutant" note on the content_type guard was wrong, and the
   comment is downgraded to say so. web.Response(text=...) defaults to
   text/plain, so the fake meter CAN serve valid JSON under the wrong mimetype.
   Test added; shipped behaviour was already correct.

3. A timed-out poll logged an empty reason: str(asyncio.TimeoutError()) is "",
   so the status page read "last error:" and then nothing, on a hung meter, at
   the moment the battery had just gone to 0 W. Falls back to the class name.
   Note str(err), not `err or ...` - an exception object is always truthy.

4. submit() sat outside the try in poll_once() and run() had no except, so a
   raise would kill the poll task permanently and SILENTLY - safe (the age
   climbs, the controller commands 0 W) but indistinguishable from a dead meter.
   Both wrapped; poll_s is already the retry cadence, so no backoff.

Also a comment at the parse_homewizard range(phases) slice: a 3-phase meter
configured as 1-phase understates the capacity-tariff figure. Filed separately,
not fixed here.

242 checks in test_p1.py (236 before, 6 new). test_control 55, test_arbiter 18,
test_maintenance 21, all untouched and green. Each new check proved non-vacuous:
six mutations, six named reds, no suite aborts, sources restored byte-identical.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Du77usMj8XNKNFZGmUiWDa

goodwe_controller/app/p1.py

@@ -840,6 +840,10 @@ def parse_homewizard(doc, phases: int, *, now: datetime | None = None,
     imp, exp = split_signed(doc.get("active_power_w"))
 
     pi = pe = None
+    # ⚠️ range(phases), not the legs the meter served: a 3-phase meter configured
+    # as meter_phases: 1 yields a per-phase tuple covering ONE leg of three.
+    # Control is unaffected (it uses the connection figure), but the
+    # capacity-tariff peak is understated. Filed separately - not fixed here.
     legs = [doc.get(f"active_power_l{i + 1}_w") for i in range(phases)]
     if all(v is not None for v in legs):
         pairs = [split_signed(v) for v in legs]
@@ -947,10 +951,24 @@ class HomeWizardLocalSource:
         return max(0.0, time.monotonic() - self._changed_mono)
 
     async def run(self) -> None:
-        """Long-lived task: poll, submit, sleep, forever."""
+        """Long-lived task: poll, submit, sleep, forever.
+
+        ⚠️ Nothing but cancellation may end this loop. An escaping exception
+        would kill the poll task for the lifetime of the add-on, and it would do
+        it QUIETLY: the failure mode is safe (no submissions, the age climbs, the
+        watchdog holds the battery at 0 W) but it looks identical to a dead
+        meter, so the operator goes hunting the wrong device. Retry on the next
+        tick instead - poll_s is already the retry cadence, so no backoff.
+        """
         _LOG.info("P1 ingest: polling %s every %.1fs", self.url, self.poll_s)
         while True:
-            await self.poll_once()
+            try:
+                await self.poll_once()
+            except asyncio.CancelledError:
+                raise
+            except Exception as err:  # noqa: BLE001 - the task must outlive it
+                _LOG.warning("P1 meter poll %s: %s - retrying in %.1fs", self.url,
+                             str(err) or type(err).__name__, self.poll_s)
             await asyncio.sleep(self.poll_s)
 
     async def poll_once(self) -> bool:
@@ -965,33 +983,43 @@ class HomeWizardLocalSource:
                 # content_type=None: the meter's own firmware is the authority on
                 # what it serves, and refusing a reading over a Content-Type
                 # header would be a fabricated outage.
-                # ⚠️ Known EQUIVALENT MUTANT: dropping this argument leaves all
-                # 236 checks green, because aiohttp's own json_response - which
-                # the fake meter in test_p1.py uses - always sets
-                # application/json, so no test can serve valid JSON under a
-                # wrong header. Recorded here rather than left for the next
-                # reviewer to rediscover. It is kept because a real HomeWizard
-                # firmware that ever answers text/plain would otherwise read as
-                # a dead meter and hold the battery at 0 W.
+                # ⚠️ Kept because a real HomeWizard firmware that ever answers
+                # text/plain would otherwise read as a dead meter and hold the
+                # battery at 0 W. (This was once recorded here as an equivalent
+                # mutant - it is not. aiohttp's json_response always sets
+                # application/json, but web.Response(text=...) defaults to
+                # text/plain, so the fake meter CAN serve valid JSON under the
+                # wrong header, and test_p1.py now does.)
                 doc = await resp.json(content_type=None)
         except asyncio.CancelledError:
             raise
         except Exception as err:  # noqa: BLE001 - any read failure is a gap
             self.connected = False
             self.poll_errors += 1
-            self.ingest.reject(f"meter poll {self.url}: {err}")
+            # ⚠️ str() of a bare asyncio.TimeoutError is the EMPTY STRING, so
+            # f"...: {err}" renders "last error:" and then nothing - on the
+            # status page, on a hung meter, at the moment the battery has just
+            # dropped to 0 W and someone is reading that line to find out why.
+            # The class name is the only thing that says "it timed out".
+            # ⚠️ str(err), not `err or ...`: an exception object is ALWAYS truthy,
+            # empty message or not, so the `or` would never reach the fallback.
+            self.ingest.reject(
+                f"meter poll {self.url}: {str(err) or type(err).__name__}")
             return False
 
         self.connected = True
         try:
             sample = parse_homewizard(doc, self.ingest.phases)
+            # ⚠️ Submitted unconditionally, INCLUDING a document identical to the
+            # last one. The response is the arrival; the number is not.
+            # Inside the try on purpose: submit() outside it would put a raise on
+            # a path with no handler at all, killing the poll task permanently -
+            # safely (the age climbs) but silently. run() backstops the rest.
+            self.ingest.submit(sample)
+            self._note(doc)
         except P1Error as err:
             self.ingest.reject(err)
             return False
-        # ⚠️ Submitted unconditionally, INCLUDING a document identical to the
-        # last one. The response is the arrival; the number is not.
-        self.ingest.submit(sample)
-        self._note(doc)
         return True
 
     def _note(self, doc) -> None: