fix(models): decode packed consumable alert lists (#79)

[sjmotew]

Fixes the confirmed bug in #79: every consumable maintain/replace alert has been silently discarded since the feature shipped.

The bug

consumable/get_consumable_info returns its two lists as packed repeated varints, and blackboxprotobuf surfaces a packed field as a str whose code points are the encoded bytes. _enum_int_list() accepted "an int, or a list of ints", so int('\x04\x06\x08\n') raised, the per-item except: continue swallowed it, and both lists came back empty.

Empty means nothing needs attention. That's what made this invisible — it failed as good news. Live capture from my Flow (AX12, v01.08.03.07), a robot that has been running for months:

{'1': {'1': '\x04\x06\x08\n', '2': '\x03\x14'}}

  maintainItems = [4, 6, 8, 10]  wash ribs, universal wheel,
                                 side distance sensor, anti-winding brush
  replaceItems  = [3, 20]        side brush, station bag

binary_sensor.maintenance_required and binary_sensor.replacement_required reported off throughout, on a robot asking for six parts.

The fix

Decode str/bytes as packed varints before the int conversion. Properly, not one byte per value — enum ids are all small today, but a byte-per-value shortcut would misread anything above 127 and hide the next surprise.

Both callers of _enum_int_list are consumable lists, so there is no genuine text field that could be mangled by treating a str as a blob.

Why a green suite missed it

The existing test fed {"1": [1, 9], "2": 8} — the shapes a hand-written payload takes, not the shape a robot sends. The test and the code shared an assumption, so they agreed with each other and not with the device.

New tests use the verbatim capture, plus the cases that would let a subtly wrong decoder pass:

• the real four-item / two-item capture
• a single-item list, where an off-by-one decoder still looks correct
• a bytes blob rather than str, so a bbp version change doesn't reintroduce it
• a multi-byte varint (300), which a byte-per-value shortcut gets wrong
• an empty blob, which must still mean healthy

255 passed, and both narwal_client copies verified identical.

Verification

Re-ran the probe against the live robot with the patched code — the same payload that previously parsed to nothing now yields maintain_items = [4, 6, 8, 10] and replace_items = [3, 20].

Scope

This closes the first checkbox in #79 only. The disputed field 38, the unverified field 41 → detergent mapping, the absent fields 21/35, and the tank-state thresholds behind #77 all still need captures from other people's hardware — the asks are listed in that issue.

[greptile-apps]

Greptile Summary

The PR fixes consumable maintenance and replacement alerts by decoding blackboxprotobuf string/byte blobs as packed protobuf varints in both client copies.

• Adds a packed-varint decoder supporting single- and multi-byte values.
• Routes packed str, bytes, and bytearray consumable fields through the decoder while retaining list and scalar handling.
• Adds regression coverage for captured device payloads, bytes, multi-byte values, single items, and empty blobs.

Confidence Score: 4/5

The PR appears safe to merge, with a non-blocking opportunity to reject overlong malformed varints before they consume excessive resources.

The intended packed consumable payloads are decoded correctly and comprehensively tested, while only malformed continuation sequences remain insufficiently bounded.

Files Needing Attention: narwal_client/models.py and custom_components/narwal/narwal_client/models.py

Important Files Changed

Filename	Overview
narwal_client/models.py	Adds packed consumable-list decoding; normal payload handling is covered, but malformed overlong varints remain unbounded.
custom_components/narwal/narwal_client/models.py	Mirrors the client decoder exactly and therefore shares its malformed-varint hardening concern.
tests/test_models.py	Adds focused regression tests covering live packed payloads and important representation and boundary cases.

_{Reviews (1): Last reviewed commit: "fix(models): decode packed consumable al..." | Re-trigger Greptile}

[greptile-apps]

Bound overlong packed varints

If a malformed consumable response contains a long sequence of continuation bytes, this loop repeatedly expands an arbitrary-precision integer without enforcing protobuf's maximum varint width, consuming disproportionate CPU and memory and potentially producing an enormous bogus consumable identifier. Rejecting overlong varints would make this device-controlled parsing path fail safely.