feat(meshcore): single-packet chat sends and AGENTS.md on-demand split

ARCHITECTURE.md

@@ -1,6 +1,6 @@
 # Architecture
 
-Project layout, data flow, and code placement for human reference. For AI coding guidelines, see [AGENTS.md](AGENTS.md) (self-contained).
+Project layout, data flow, and code placement for human reference. For AI coding guidelines, see [AGENTS.md](AGENTS.md) (hard rules) and the subsystem references in [docs/agents/](docs/agents/README.md).
 
 ## Layout map
 
@@ -31,7 +31,7 @@ Path alias `@/*` maps to `src/*` (see `tsconfig.json`).
 
 ## Multi-protocol (Meshtastic + MeshCore + Reticulum)
 
-All three stacks can run at once: independent sessions, header switcher for focus (green / cyan / amber), inactive protocols stay connected, per-protocol unread badges. Meshtastic and MeshCore use `ConnectionDriver` for RF/MQTT; Reticulum uses the AGPL sidecar (`useReticulumRuntime`; no Noble/MQTT for Reticulum's own connections — the sidecar owns BLE RNode via `btleplug`). A Reticulum BLE RNode connect on macOS/Windows may still briefly suspend/yield Noble so it does not contend with the sidecar's BLE scan (see [AGENTS.md](AGENTS.md) **Multi-protocol BLE**). Capabilities differ (e.g. Meshtastic: full Security PKI/Modules/TAK; MeshCore: partial Security backup/restore, Repeaters, **Rooms** BBS; Reticulum: LXMF DMs, **Remote** rnsh/rncp (`hasReticulumRemotePanel`), **Nomad Network / My Pages** (`hasNomadNetworkPanel`), **Peers**, **RRC** hub chat (`hasRrcPanel`), propagation, RNode flasher, **Map** (RMAP v4 discovery), Topology). Sidebar tab slots are fixed in `src/renderer/lib/tabSlotIds.ts`; visibility is computed in `src/renderer/lib/appTabMappings.ts` (`computeTabMappings()` consumed from `App.tsx`); **Rooms** requires `hasRoomServersPanel`, Reticulum panels gate on `hasReticulumNetworkPanel` / `hasReticulumInterfaceConfig` / `hasReticulumDiscoveryMap` / `hasRrcPanel` / `hasReticulumRemotePanel` / `hasNomadNetworkPanel`, **Security**/`TAK` require capability flags (~16 visible tabs per LoRa protocol; MeshCore hides TAK; Reticulum hides LoRa-specific tabs).
+All three stacks can run at once: independent sessions, header switcher for focus (green / cyan / amber), inactive protocols stay connected, per-protocol unread badges. Meshtastic and MeshCore use `ConnectionDriver` for RF/MQTT; Reticulum uses the AGPL sidecar (`useReticulumRuntime`; no Noble/MQTT for Reticulum's own connections — the sidecar owns BLE RNode via `btleplug`). A Reticulum BLE RNode connect on macOS/Windows may still briefly suspend/yield Noble so it does not contend with the sidecar's BLE scan (see [docs/agents/ble-serial.md](docs/agents/ble-serial.md) **Multi-protocol BLE coexistence**). Capabilities differ (e.g. Meshtastic: full Security PKI/Modules/TAK; MeshCore: partial Security backup/restore, Repeaters, **Rooms** BBS; Reticulum: LXMF DMs, **Remote** rnsh/rncp (`hasReticulumRemotePanel`), **Nomad Network / My Pages** (`hasNomadNetworkPanel`), **Peers**, **RRC** hub chat (`hasRrcPanel`), propagation, RNode flasher, **Map** (RMAP v4 discovery), Topology). Sidebar tab slots are fixed in `src/renderer/lib/tabSlotIds.ts`; visibility is computed in `src/renderer/lib/appTabMappings.ts` (`computeTabMappings()` consumed from `App.tsx`); **Rooms** requires `hasRoomServersPanel`, Reticulum panels gate on `hasReticulumNetworkPanel` / `hasReticulumInterfaceConfig` / `hasReticulumDiscoveryMap` / `hasRrcPanel` / `hasReticulumRemotePanel` / `hasNomadNetworkPanel`, **Security**/`TAK` require capability flags (~16 visible tabs per LoRa protocol; MeshCore hides TAK; Reticulum hides LoRa-specific tabs).
 
 **Feature gating:** use `ProtocolCapabilities` via `useRadioProvider(protocol)` from `src/renderer/lib/radio/providerFactory.ts`; do not branch on raw `protocol === 'meshcore'` strings.
 
@@ -74,7 +74,7 @@ Sanitize user-controlled strings before logs and IPC per [AGENTS.md](AGENTS.md).
 
 **First places to look:** `runtime/useMeshtasticRuntime.ts` / `runtime/useMeshcoreRuntime.ts` (protocol side effects); `hooks/useProtocolConnection.ts` (connect); `stores/*` (UI state); `src/main/index.ts` (IPC).
 
-**Renderer layers:** `runtime/` (single-mount protocol runtimes), `hooks/` (facades and store selectors), `lib/` (drivers, sessions, types), `stores/` (identity-scoped UI: `identityStore`, `nodeStore`, `messageStore`, `connectionStore`; Reticulum also uses session-global `reticulumIdentityStore` for sidecar identity status). Prefer `useProtocolFacade(protocol)` in App for new wiring. Hook/runtime boundaries: [AGENTS.md](AGENTS.md#renderer-hook-architecture-multi-protocol) ([#375](https://github.com/Colorado-Mesh/mesh-client/issues/375), [#377](https://github.com/Colorado-Mesh/mesh-client/issues/377)).
+**Renderer layers:** `runtime/` (single-mount protocol runtimes), `hooks/` (facades and store selectors), `lib/` (drivers, sessions, types), `stores/` (identity-scoped UI: `identityStore`, `nodeStore`, `messageStore`, `connectionStore`; Reticulum also uses session-global `reticulumIdentityStore` for sidecar identity status). Prefer `useProtocolFacade(protocol)` in App for new wiring. Hook/runtime boundaries: [docs/agents/renderer-hooks.md](docs/agents/renderer-hooks.md) ([#375](https://github.com/Colorado-Mesh/mesh-client/issues/375), [#377](https://github.com/Colorado-Mesh/mesh-client/issues/377)).
 
 **Drivers / identity bridge:** `lib/drivers/ConnectionDriver.ts` owns RF/MQTT session lifecycle and dispatches Protocol events into `lib/drivers/PacketRouter.ts` (store ingest first, then side-effect listeners). `PacketRouter` invokes generic listeners before event-type listeners, in registration order within each group; attach persistence/ingest before dependent UI side effects. `lib/meshIdentityBridge.ts` builds transport params and attaches Meshtastic Protocol ingress; `lib/identityStoreReads.ts` is the canonical read path for identity-scoped nodes/messages (`getIdentityNode` / `getIdentityChatMessages`).
 
@@ -90,7 +90,7 @@ Sanitize user-controlled strings before logs and IPC per [AGENTS.md](AGENTS.md).
 - **`useRendererHeartbeat`** / **`useLongSessionMaintenance`** — renderer pings main every 30s; main `rendererHeartbeatWatchdog` warns if no heartbeat within 30s after resume **while visible**, and polls for a **90s visible-window stall**; sticky `rendererUnresponsiveSeen` + `getRendererLiveness()` feed support snapshot `mainLiveness`; long-uptime restart nudge.
 - **`ProtocolAutoConnectCoordinator`** / **`useProtocolRfAutoConnect`** — silent launch auto-connect for remembered serial/BLE/TCP/HTTP (cancel gate before manual Connect).
 - **`rfReconnectController`** — LoRa single-owner reconnect scheduling shared by Meshtastic/MeshCore runtimes.
-- **Dual-radio Noble BLE startup** (Meshtastic + MeshCore different peripherals): `lib/meshcoreDualNobleBleInit.ts` initialized from `App.tsx` `useLayoutEffect`; primary order from `mesh-client:protocol` localStorage — see [AGENTS.md](AGENTS.md) **Dual-radio Noble BLE startup**.
+- **Dual-radio Noble BLE startup** (Meshtastic + MeshCore different peripherals): `lib/meshcoreDualNobleBleInit.ts` initialized from `App.tsx` `useLayoutEffect`; primary order from `mesh-client:protocol` localStorage — see [docs/agents/ble-serial.md](docs/agents/ble-serial.md) **Dual-radio Noble BLE startup**.
 
 ### Database
 

README.md

@@ -184,8 +184,8 @@ These sections apply to the two LoRa companion-radio stacks. Reticulum uses the
 
 - Send/receive messages across channels with per-transport delivery badges and delivery ACK / failure states
 - **Durable outbox**: outgoing messages are queued in SQLite and retried until delivered; survive app restarts and connection drops
-- **Long message chunking**: messages over the payload limit are auto-split into sequential `[N/T]`-prefixed chunks (word-boundary split, max 9 chunks); MeshCore MQTT-only connections are guarded from sending when no RF path is available
-- **Shared composer** (`ChatComposer`): drafts, mentions, chunking, spellcheck, and emoji picker used by **Chat** and **MeshCore Rooms**; right‑click misspelling replacements (Electron spellchecker for both protocols)
+- **Long message chunking (Meshtastic / Reticulum)**: messages over the payload limit are auto-split into sequential `[N/T]`-prefixed chunks (word-boundary split, max 9 chunks). **MeshCore is single-packet**: each message is sent as one radio packet and longer text is blocked with an explanatory notice (busy repeaters drop split parts — see [Limitations](#limitations)). MeshCore MQTT-only connections are also guarded from sending when no RF path is available
+- **Shared composer** (`ChatComposer`): drafts, mentions, protocol-aware length limits (chunking for Meshtastic / Reticulum; single-packet for MeshCore, see above), spellcheck, and emoji picker used by **Chat** and **MeshCore Rooms**; right‑click misspelling replacements (Electron spellchecker for both protocols)
 - **Emoji reactions / tapbacks**: Meshtastic — 12 quick-pick reactions plus compose emoji (native panel on macOS/Windows; `emoji-picker-element` on Linux); wire tapbacks decode payload UTF-8 glyphs (flags, ZWJ sequences, and legacy index 1–12). MeshCore — same picker UX; **default** outbound tapbacks and text replies use keyless companion wire `@[Display Name] …` (inbound keyed `@[Name#key]`, Open `r:HASH:INDEX`, and `g:GIFID` also parsed). Optional **MeshCore Open compatibility** in App settings enables keyed replies, `r:` reactions, and Giphy GIF send — see [docs/meshcore-meshtastic-parity.md](docs/meshcore-meshtastic-parity.md#meshcore-emoji-reactions-tapbacks); reply-to-message with quoted preview in bubble (including room BBS posts)
 - **System tray**: docked/minimized on macOS and Windows shows an unread indicator when chat or MeshCore **Rooms** traffic arrives while the window is in the background
 - **`@[Display Name]` tokens** (Meshtastic / MeshCore reply, tapback, path, and inline-reference syntax) render as compact inline labels in the bubble instead of raw brackets; see [docs/meshcore-meshtastic-parity.md](docs/meshcore-meshtastic-parity.md#chat-mention-tokens)
@@ -383,6 +383,7 @@ Architecture and API: [docs/reticulum.md](docs/reticulum.md). Games wire parity:
 - **MQTT → RF (MeshCore JSON)**: Not supported; MeshCore MQTT is chat ingest only.
 - **Meshtastic - PKC remote admin**: Configure-node-over-MQTT is not supported; a connected local RF radio is required to reach remote nodes (firmware 2.5+).
 - **MeshCore - MQTT (JSON v1)**: The Connection tab can connect to an MQTT broker in MeshCore mode using a small JSON chat envelope (see [docs/meshcore-meshtastic-parity.md](docs/meshcore-meshtastic-parity.md)). This is separate from Meshtastic's protobuf MQTT pipeline.
+- **Breaking change — MeshCore single-packet messages (no multi-part / multi-split)**: mesh-client **no longer** auto-splits outbound MeshCore chat, DM, or room messages into numbered `[i/N]` packets. Each send is one radio packet (max ~130-160 characters depending on context and sender name); longer text is **blocked** with an explanatory notice in the composer. On a busy mesh, repeaters routinely drop some split parts, so recipients previously got silently incomplete messages. **Migration:** shorten long messages, or send them as a few separate shorter messages. A non-blocking advisory also appears if you send faster than the mesh can relay (~5s). Call this out in release notes. Upstream: [meshcore-dev/MeshCore#1502](https://github.com/meshcore-dev/MeshCore/issues/1502), [#2820](https://github.com/meshcore-dev/MeshCore/issues/2820), [#3053](https://github.com/meshcore-dev/MeshCore/issues/3053). Inbound multi-part from other clients is still merged for display. Meshtastic multi-split (up to 9 parts) is unchanged.
 - **MeshCore - partial routing diagnostics**: MeshCore supports `route_flapping` / `path_instability` (PathUpdated events) and `weak_link` (when `hasPerHopSnr` and a trace is completed). Distance-based `hop_goblin` / close-in `bad_route` are Meshtastic-only (`hasDistanceBasedHopAnomalies`). Full hop-anomaly detection and Meshtastic-style LocalStats RF findings require Meshtastic packets; MeshCore provides its own RF findings (Elevated Noise Floor, Excessive Flooding) from Repeater Status packet stats. **Foreign LoRa** tables render on the Meshtastic tab only (MeshCore may record overhear internally).
 - **MeshCore - channel editing**: Can add/edit/delete channels (name + PSK) via the Radio tab, but does not expose Meshtastic-style full protobuf config. Radio parameters (frequency, bandwidth, spreading factor, coding rate, TX power) can be set via the Radio tab.
 - **MeshCore - remote telemetry availability**: `getTelemetry` requires the remote node to have environment sensors. A timeout is returned if the node has no sensor data.

docs/agents/README.md

@@ -0,0 +1,20 @@
+# Agent subsystem reference
+
+Deep, file-level subsystem detail for AI assistants, split out of [`AGENTS.md`](../../AGENTS.md) so it is loaded on demand rather than on every prompt. Hard rules and the always-on workflow/security/style policy stay in `AGENTS.md`; open the matching file here when a task touches that subsystem.
+
+| When working on…                                                                         | Read                                           |
+| ---------------------------------------------------------------------------------------- | ---------------------------------------------- |
+| Reticulum sidecar, LXMF, propagation, Remote/rnsh/rncp, Nomad, RRC, voice, games         | [reticulum.md](reticulum.md)                   |
+| LoRa BLE/serial, Noble reconnect, dual-radio startup, BLE coexistence                    | [ble-serial.md](ble-serial.md)                 |
+| Renderer hooks/runtimes/stores, protocol entry points, DB, tab wiring                    | [renderer-hooks.md](renderer-hooks.md)         |
+| Meshtastic config apply, admin, channel URLs, Store & Forward, remote admin, GPS         | [meshtastic.md](meshtastic.md)                 |
+| MQTT ingest, channel key mapping, sticky BLE suppress                                    | [mqtt.md](mqtt.md)                             |
+| Chat panel, composer, link previews, notifications, dedup, hop badges, reactions, export | [chat.md](chat.md)                             |
+| MeshCore Repeaters admin (ping/trace/neighbors/CLI/waiting drain)                        | [meshcore-repeaters.md](meshcore-repeaters.md) |
+| MeshCore Rooms (BBS) login/post/sync/wire text                                           | [meshcore-rooms.md](meshcore-rooms.md)         |
+| Diagnostics engines, rows, tab scoping                                                   | [diagnostics.md](diagnostics.md)               |
+| i18n / localization workflow, auto-translate, language selector                          | [i18n.md](i18n.md)                             |
+| Connection panel helpers (error hints, rehydrate, storage migrations)                    | [connection-panel.md](connection-panel.md)     |
+| Symptom → where-to-check index                                                           | [common-issues.md](common-issues.md)           |
+
+For human-facing deep dives, see the top-level docs (e.g. [../reticulum.md](../reticulum.md), [../diagnostics.md](../diagnostics.md), [../meshcore-meshtastic-parity.md](../meshcore-meshtastic-parity.md), [../troubleshooting.md](../troubleshooting.md)).