feat(hid): Unifying receiver support

[cserby]

Summary

OpenLogi previously only enumerated Logi Bolt receivers (PID 0xC548). Users with a Unifying receiver (PID 0xC52B / 0xC532) saw no devices in the GUI or CLI.

This PR adds full Unifying receiver support:

• Protocol layer (openlogi-hidpp): implement the missing HID++ 1.0 methods on UnifyingReceiver — count_pairings, trigger_device_arrival, get_device_pairing_information, device-connection event listener (0x41 sub_id), DeviceKind enum (shifted vs Bolt at values ≥5).
• Transport filter (openlogi-hid): the hid-logitech-dj kernel driver creates a virtual hidraw node per paired Unifying device; these matched the HID++ filter and caused 5-second probe timeouts every enumeration tick. Added is_receiver_child_node() (Linux) that checks the sysfs path and filters them before probing.
• Inventory (openlogi-hid): split probe_one to handle Receiver::Unifying separately. Added probe_unifying_receiver / probe_unifying_slot that build PairedDevice entries from device-arrival events. Added UNIFYING_SLOT_PROBE (3.5 s) per-slot budget so a slow wireless HID++ 2.0 round-trip cannot consume the shared PROBE_BUDGET.
• Routing (openlogi-hid): add DeviceRoute::Unifying variant; add DeviceRoute::device_route_for() constructor that picks the right variant from the receiver's product ID; consolidate BOLT_PIDS / UNIFYING_PIDS as the single source of truth (previously duplicated in three places).
• App stack (openlogi-agent-core, openlogi-gui, openlogi-cli): update all routing call sites, fix "Bolt receiver" label, add "Unifying receiver" label, surface devices that lack HID++ 2.0 model info in the carousel (wpid-based config key), hide the mouse-model Buttons tab for keyboards without an asset.

Verified on hardware

• Logitech Unifying receiver (C52B) — K540/K545 keyboard (slot 1) and M510 mouse (slot 2) both appear in the carousel
• Logitech MX Anywhere 3 over Bluetooth — still appears correctly
• Device tab shows "Unifying receiver" (not "Bolt receiver")
• K540 keyboard shows only the Device tab (no spurious mouse Buttons panel)
• M510 mouse shows Buttons + Device tabs

Known limitations

• Offline Unifying devices (paired but sleeping) are not surfaced — the 0xB5/0x5N pairing-info register returns InvalidValue; the sub-register format differs from Bolt and needs further investigation.
• K540 model info is absent on the first few enumeration ticks — the K540 takes ~3 s for the HID++ 2.0 version ping (slow wireless round-trip); the 3.5 s per-slot budget covers it, but feature enumeration may still miss on very slow hardware.
• The CacheKey::Bolt sentinel [0,0,0,slot] is reused for Unifying slot caching (no unit_id available without working pairing-info register); documented in the code.

Test plan

• cargo test --workspace passes (18 new unit tests across 5 crates)
• cargo clippy --workspace -- -D warnings clean
• Run ./target/debug/openlogi-agent + ./target/debug/openlogi-gui — all three devices appear in the carousel
• Device tab on Unifying devices shows "Unifying receiver"
• K540 shows only Device tab; M510 shows Buttons + Device tabs

🤖 Generated with Claude Code

[greptile-apps]

Greptile Summary

This PR adds full Logi Unifying receiver support to OpenLogi. Previously only Bolt (PID 0xC548) receivers were enumerated; users with Unifying receivers (PIDs 0xC52B/0xC532) saw no devices.

• Protocol layer (openlogi-hidpp): Implements HID++ 1.0 methods on UnifyingReceiver — count_pairings, trigger_device_arrival, device-connection event listener (sub_id 0x41), DeviceKind enum, and the ListenerDropGuard/Arc pattern (fixing the clone/drop listener issue from prior review).
• Transport (openlogi-hid): is_receiver_child_node() on Linux detects and filters virtual per-device hidraw nodes created by hid-logitech-dj before they cause 5-second probe timeouts.
• Inventory (openlogi-hid): probe_unifying_receiver + probe_unifying_slot build PairedDevice entries from device-arrival events; uses CacheKey::UnifyingSlot { receiver_uid, slot } with the full receiver serial to prevent cross-receiver cache collisions (addressing prior review concern); a 3.5 s per-slot timeout prevents slow HID++ 2.0 round-trips from blocking the shared probe budget; timeout fallback now returns cached data via cached.map_or_else(...) (addressing prior review concern).
• Routing and UI: DeviceRoute::Unifying variant, device_route_for() constructor, devices without HID++ 2.0 model info are now surfaced using wpid/slot as config key, and the Buttons tab is correctly suppressed for keyboards without a resolved asset.

Confidence Score: 5/5

All three issues flagged in the prior review have been addressed; the new Unifying probe path is well-structured, hardware-verified, and covered by 18 new unit tests across 5 crates.

The previous blocking findings — Clone/Drop sharing a raw listener handle, cross-receiver cache key collisions, and the timeout fallback discarding good cached data — are each correctly resolved. No new correctness bugs were found in this pass. The timing budget for a Unifying probe (ARRIVAL_DRAIN + concurrent UNIFYING_SLOT_PROBE) sits right at PROBE_BUDGET but is hardware-confirmed to work, and a miss just defers to the next tick. The only remaining note is a cosmetic Option wrapper that is never None.

No files require special attention. The sysfs child-node filter (transport.rs) and the ListenerDropGuard pattern (receiver/mod.rs) are the most novel additions and both look correct.

Important Files Changed

Filename	Overview
crates/openlogi-hidpp/src/receiver/unifying.rs	New HID++ 1.0 implementation for Unifying receiver: adds count_pairings, trigger_device_arrival, device-connection listener (sub_id 0x41), DeviceKind enum (shifted vs Bolt at ≥5), and get_device_pairing_information; uses Arc correctly to fix the prior Clone/Drop listener issue.
crates/openlogi-hid/src/inventory.rs	Core Unifying inventory logic: adds probe_unifying_receiver, probe_unifying_slot, drain_device_arrival_unifying, and CacheKey::UnifyingSlot with full receiver serial to prevent cross-receiver cache collisions; timeout fallback now correctly returns cached data rather than a bare default; probe_unifying_slot always returns Some but its Option return type is vestigial.
crates/openlogi-hid/src/transport.rs	Adds is_receiver_child_node (Linux) that resolves the sysfs path and checks for a known receiver PID as a parent component; filters virtual hid-logitech-dj child nodes before probing to eliminate spurious 5-second timeouts; unit-tested with realistic sysfs paths.
crates/openlogi-hid/src/route.rs	Adds DeviceRoute::Unifying variant (same receiver_uid+slot structure as Bolt), BOLT_PIDS/UNIFYING_PIDS constants, device_route_for() factory that picks the right variant by PID; open_route_channel handles the Unifying variant by detecting via get_unique_id(); well-covered by tests.
crates/openlogi-hidpp/src/receiver/mod.rs	Introduces ListenerDropGuard (chan + hdl in Arc) shared by both BoltReceiver and UnifyingReceiver; ensures remove_msg_listener is called exactly once when the last clone's Arc reaches zero, fixing the prior Clone+Drop listener issue.
crates/openlogi-gui/src/app.rs	tabs_for now shows Buttons only when asset is resolved or device is a pointer type, preventing the mouse-model silhouette from appearing for keyboards with ReprogControls; adds route_label for Unifying variant; updated tests cover both new cases.
crates/openlogi-gui/src/state/devices.rs	build_device_list no longer skips devices without HID++ 2.0 model info; falls back to wpid-based or slot-based config key; consolidates device_route() helper into DeviceRoute::device_route_for(); new tests cover the wpid/slot fallback cases.

Sequence Diagram

sequenceDiagram
    participant E as Enumerator
    participant T as Transport
    participant U as UnifyingReceiver
    participant C as HidppChannel
    participant S as probe_unifying_slot

    E->>T: enumerate_hidpp_devices()
    note over T: filter is_receiver_child_node (Linux)
    T-->>E: [hidraw nodes, child nodes excluded]

    E->>C: open_hidpp_channel(dev)
    E->>U: receiver::detect() → Receiver::Unifying
    E->>U: get_unique_id() → serial
    E->>U: count_pairings() → count

    E->>U: trigger_device_arrival()
    loop ARRIVAL_DRAIN (1.5 s per event)
        U-->>E: "DeviceConnection { index, kind, wpid, online }"
    end

    par "concurrent per online slot (UNIFYING_SLOT_PROBE = 3.5 s each)"
        E->>S: probe_unifying_slot(conn, receiver_uid)
        S->>C: read_codename (0xFF/0xB5/0x6N — receiver register)
        S->>C: "probe_or_reuse(slot, online=true)"
        C-->>S: "ProbedFeatures { battery, model_info, capabilities }"
        S-->>E: PairedDevice + CacheOutcome
    end

    E-->>E: "DeviceInventory { receiver, paired[] }"
    E-->>E: apply CacheOutcome updates

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