#23614: feat(routing): add sessionScope binding override for session key scoping

## Summary By default, each group/channel/guild gets its own isolated session. This means the agent has no memory of DM conversations when talking in a group, and vice versa. The new `overrideDmScope` option on agent bindings allows specific channels to reuse the agent's main session — the same session used for DMs. This is useful for "inner circle" groups where you want the agent to have full context of all prior conversations, behaving as a single continuous session across DMs and selected groups. ## Changes - **`src/config/types.agents.ts`** — Added optional `overrideDmScope?: DmScope` field to `AgentBinding` - **`src/routing/session-key.ts`** — `buildAgentPeerSessionKey` now accepts `overrideDmScope`; when set to `"main"`, short-circuits to `buildAgentMainSessionKey` - **`src/routing/resolve-route.ts`** — `buildAgentSessionKey` and `resolveAgentRoute` extract `overrideDmScope` from the matched binding and pass it through - **`src/routing/resolve-route.test.ts`** — 6 new tests covering Telegram, Discord, WhatsApp, Slack, default (no override), and non-matching binding ## Example config ```yaml bindings: # Shared session with DMs - agentId: main match: channel: telegram peer: kind: group id: "-1003691588332" overrideDmScope: main # → agent:main:main # Discord server — shared session - agentId: main match: channel: discord guildId: "123456789" overrideDmScope: main # Normal group — isolated (default behavior) - agentId: main match: channel: telegram peer: kind: group id: "-1009999999999" # No overrideDmScope → agent:main:telegram:group:-1009999999999 ``` ## How it works The `overrideDmScope` field on a binding overrides the default session key derivation for that binding's matched context. It reuses the existing `DmScope` type: | Value | Session key behavior | | -------------------------- | ------------------------------------------------------------- | | `"main"` | Collapses to `agent:<id>:main` — same session as DMs | | `"per-peer"` | Isolates by peer ID only | | `"per-channel-peer"` | Isolates by channel + peer ID | | `"per-account-channel-peer"` | Isolates by account + channel + peer ID | | *(not set)* | Default behavior — isolated per channel/peer for groups | ## Test plan - [x] All 40 existing + 6 new routing tests pass - [x] Verify Telegram group binding with `overrideDmScope: main` shares session with DMs - [ ] Verify Discord guild binding with `overrideDmScope: main` collapses session key - [ ] Verify bindings without `overrideDmScope` retain isolated session keys