Discord: thread bindings idle + max-age lifecycle (#27845) (thanks @osolmaz)

* refactor discord thread bindings to idle and max-age lifecycle

* fix: migrate legacy thread binding expiry and reduce hot-path disk writes

* refactor: remove remaining thread-binding ttl legacy paths

* fix: harden thread-binding lifecycle persistence

* Discord: fix thread binding types in message/reply paths

* Infra: handle win32 unknown inode in file identity checks

* Infra: relax win32 guarded-open identity checks

* Config: migrate threadBindings ttlHours to idleHours

* Revert "Infra: relax win32 guarded-open identity checks"

This reverts commit de94126771.

* Revert "Infra: handle win32 unknown inode in file identity checks"

This reverts commit 96fc5ddfb3.

* Discord: re-read live binding state before sweep unbind

* fix: add changelog note for thread binding lifecycle update (#27845) (thanks @osolmaz)

---------

Co-authored-by: Onur Solmaz <onur@textcortex.com>

docs/gateway/configuration-reference.md

@@ -268,7 +268,8 @@ WhatsApp runs through the gateway's web channel (Baileys Web). It starts automat
       },
       threadBindings: {
         enabled: true,
-        ttlHours: 24,
+        idleHours: 24,
+        maxAgeHours: 0,
         spawnSubagentSessions: false, // opt-in for sessions_spawn({ thread: true })
       },
       voice: {
@@ -303,8 +304,9 @@ WhatsApp runs through the gateway's web channel (Baileys Web). It starts automat
 - Bot-authored messages are ignored by default. `allowBots: true` enables them (own messages still filtered).
 - `maxLinesPerMessage` (default 17) splits tall messages even when under 2000 chars.
 - `channels.discord.threadBindings` controls Discord thread-bound routing:
-  - `enabled`: Discord override for thread-bound session features (`/focus`, `/unfocus`, `/agents`, `/session ttl`, and bound delivery/routing)
-  - `ttlHours`: Discord override for auto-unfocus TTL (`0` disables)
+  - `enabled`: Discord override for thread-bound session features (`/focus`, `/unfocus`, `/agents`, `/session idle`, `/session max-age`, and bound delivery/routing)
+  - `idleHours`: Discord override for inactivity auto-unfocus in hours (`0` disables)
+  - `maxAgeHours`: Discord override for hard max age in hours (`0` disables)
   - `spawnSubagentSessions`: opt-in switch for `sessions_spawn({ thread: true })` auto thread creation/binding
 - `channels.discord.ui.components.accentColor` sets the accent color for Discord components v2 containers.
 - `channels.discord.voice` enables Discord voice channel conversations and optional auto-join + TTS overrides.
@@ -1374,7 +1376,8 @@ See [Multi-Agent Sandbox & Tools](/tools/multi-agent-sandbox-tools) for preceden
     },
     threadBindings: {
       enabled: true,
-      ttlHours: 24, // default auto-unfocus TTL for thread-bound sessions (0 disables)
+      idleHours: 24, // default inactivity auto-unfocus in hours (`0` disables)
+      maxAgeHours: 0, // default hard max age in hours (`0` disables)
     },
     mainKey: "main", // legacy (runtime always uses "main")
     agentToAgent: { maxPingPongTurns: 5 },
@@ -1411,7 +1414,8 @@ See [Multi-Agent Sandbox & Tools](/tools/multi-agent-sandbox-tools) for preceden
   - `highWaterBytes`: optional target after budget cleanup. Defaults to `80%` of `maxDiskBytes`.
 - **`threadBindings`**: global defaults for thread-bound session features.
   - `enabled`: master default switch (providers can override; Discord uses `channels.discord.threadBindings.enabled`)
-  - `ttlHours`: default auto-unfocus TTL in hours (`0` disables; providers can override)
+  - `idleHours`: default inactivity auto-unfocus in hours (`0` disables; providers can override)
+  - `maxAgeHours`: default hard max age in hours (`0` disables; providers can override)
 
 </Accordion>