fix(unifying): enable wireless notifications so paired devices enumerate

[laofun]

Summary

A device on a Unifying receiver wouldn't show up even while connected. The
receiver only re-broadcasts arrival events while wireless notifications
(register 0x00) are on, and we never enabled it — so the trigger got ACK'd
but emitted nothing. Solaar does this before listing.

Changes

• Enable wireless notifications before draining arrivals.
• Derive online from the feature walk succeeding (event.online was always
  "offline" here).
• Read device names at Unifying's 0x40 base instead of Bolt's 0x60, and
  clamp the reported length.
• Dedup repeated arrivals per slot.

Testing

Tested on an MX Master 2S over a Unifying receiver. Added unit tests for the
name parser (normal, over-long length, short response).

[greptile-apps]

Greptile Summary

This PR fixes Unifying receiver enumeration by enabling wireless notifications (register 0x00) before triggering device-arrival events, mirroring Solaar's approach. It also corrects the online-status derivation (from a wrong event bit to feature-walk success), fixes the name sub-register base (0x40 vs. Bolt's 0x60), and deduplicates repeated 0x41 arrivals per slot.

• Wireless notification enable: set_wireless_notifications(true) is called before trigger_device_arrival; uses a read-modify-write on register 0x00 to avoid clobbering SOFTWARE_PRESENT.
• Online flag fix: online is now derived from probe.capabilities.is_some() instead of event.online, which was always wrong for triggered arrivals (bit6 always set in wire-captured payloads).
• Name reader: New read_codename_unifying / parse_codename_unifying functions read from sub-register base 0x40 + (n-1) with length clamping; three unit tests added to cover normal, over-long, and short-response cases.

Confidence Score: 4/5

Safe to merge for the core enumeration fix; one logic gap in error handling could transiently clear the device list on a first-cycle HID read failure.

The wireless-notification enable, name-register fix, and online-flag correction are all well-motivated and wire-verified. The one concern is drain_device_arrival_unifying: when set_wireless_notifications fails but trigger_device_arrival succeeds, the function returns Some([]) rather than None, telling the ledger 'no devices found' instead of 'probe unreliable — use last snapshot.' On a fresh attach combined with a transient HID read error, this would show all paired devices as offline for that cycle.

crates/openlogi-hid/src/inventory.rs — specifically the error handling in drain_device_arrival_unifying

Important Files Changed

Filename	Overview
crates/openlogi-hid/src/inventory.rs	Adds wireless-notification enable before arrival drain, dedup+sort for duplicate 0x41 events, Unifying-specific name reader with length clamping, and corrects online flag to use feature-walk success. One logic gap: a failed set_wireless_notifications is silently swallowed, causing Some([]) to be returned rather than None when the WIRELESS bit was not already set.
crates/openlogi-hidpp/src/receiver/unifying.rs	Adds Register::Notifications = 0x00 enum variant and set_wireless_notifications() with read-modify-write to avoid clobbering SOFTWARE_PRESENT. Adds clarifying NOTE to DeviceCodename = 0x60 about the Bolt-vs-Unifying base address discrepancy.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant Inv as inventory.rs
    participant Uni as UnifyingReceiver
    participant HW as Receiver HW

    Inv->>Uni: drain_device_arrival_unifying()
    Uni->>HW: read_register(0x00) [Notifications]
    HW-->>Uni: current flags
    Uni->>HW: "write_register(0x00, flags | WIRELESS)"
    HW-->>Uni: ACK
    Note over Inv,HW: WIRELESS bit now set — 0x41 events will flow
    Uni->>HW: trigger_device_arrival (write 0x02)
    HW-->>Uni: ACK
    HW-)Uni: 0x41 DeviceConnection (slot 1)
    HW-)Uni: 0x41 DeviceConnection (slot 1, duplicate)
    Uni-->>Inv: Some([conn_slot1, conn_slot1])
    Note over Inv: Dedup by slot index (HashMap), then sort
    Inv->>Uni: read_long_register(0xFF, 0xB5, [0x40+slot-1, …])
    HW-->>Uni: [sub, len, name bytes, padding]
    Note over Inv: parse_codename_unifying clamps len
    Inv->>HW: "probe_or_reuse(slot, online=true)"
    HW-->>Inv: capabilities (Some → online, None → offline)

Loading

%%{init: {'theme': 'base', 'themeVariables': {"darkMode": true, "background": "#0d1117", "primaryColor": "#21262d", "primaryTextColor": "#e6edf3", "primaryBorderColor": "#8b949e", "lineColor": "#8b949e", "textColor": "#e6edf3", "edgeLabelBackground": "#161b22", "actorBkg": "#21262d", "actorBorder": "#8b949e", "actorTextColor": "#e6edf3", "actorLineColor": "#8b949e", "signalColor": "#8b949e", "signalTextColor": "#e6edf3", "noteBkgColor": "#373320", "noteBorderColor": "#d4a72c", "noteTextColor": "#f0e6c0", "labelBoxBkgColor": "#21262d", "labelBoxBorderColor": "#8b949e", "labelTextColor": "#e6edf3", "loopTextColor": "#e6edf3", "activationBkgColor": "#30363d", "activationBorderColor": "#8b949e"}}}%%
sequenceDiagram
    participant Inv as inventory.rs
    participant Uni as UnifyingReceiver
    participant HW as Receiver HW

    Inv->>Uni: drain_device_arrival_unifying()
    Uni->>HW: read_register(0x00) [Notifications]
    HW-->>Uni: current flags
    Uni->>HW: "write_register(0x00, flags | WIRELESS)"
    HW-->>Uni: ACK
    Note over Inv,HW: WIRELESS bit now set — 0x41 events will flow
    Uni->>HW: trigger_device_arrival (write 0x02)
    HW-->>Uni: ACK
    HW-)Uni: 0x41 DeviceConnection (slot 1)
    HW-)Uni: 0x41 DeviceConnection (slot 1, duplicate)
    Uni-->>Inv: Some([conn_slot1, conn_slot1])
    Note over Inv: Dedup by slot index (HashMap), then sort
    Inv->>Uni: read_long_register(0xFF, 0xB5, [0x40+slot-1, …])
    HW-->>Uni: [sub, len, name bytes, padding]
    Note over Inv: parse_codename_unifying clamps len
    Inv->>HW: "probe_or_reuse(slot, online=true)"
    HW-->>Inv: capabilities (Some → online, None → offline)

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_{Reviews (4): Last reviewed commit: "fix(unifying): enable wireless notificat..." | Re-trigger Greptile}

[laofun]

Addressed both review notes: the deduped connection list is now sorted by slot so device order is stable across probe cycles, and added a note on InfoSubRegister::DeviceCodename clarifying that 0x60 is the Bolt base while Unifying name reads go through the wire-verified 0x40 path in inventory.rs.

[AprilNEA]

This looks like the right direction overall — enabling the Unifying notification stream before trigger_device_arrival, correcting the 0x40 name base, and deduping repeated arrivals are all well-scoped, and CI is green.

One edge I’d tighten: set_wireless_notifications(true) currently writes the whole notifications register as [0, 1, 0]. That sets the wireless bit, but it also clears any other notification flags already enabled on register 0x00. In this repo, the pairing flow writes [0x00, 0x09, 0x00] (WIRELESS | SOFTWARE_PRESENT) before streaming pairing events, so an inventory poll during/near pairing could accidentally drop the software-present bit or any future notification flag.

Could we make this read-modify-write, or at least use the same named notification flag constants as pairing.rs so the intended bitmask is explicit? The rest of the PR looks good to me.

[laofun]

Good catch — switched set_wireless_notifications to read-modify-write: it now reads the notifications register first and only flips the WIRELESS bit, so SOFTWARE_PRESENT and any other flags are preserved.