Document Hermes-owned session titles

Author: eimexdev

CONTEXT.md

@@ -30,6 +30,10 @@ _Avoid_: Project thread, workspace, channel
 The durable Hermes-owned conversation context that the agent continues across turns.
 _Avoid_: T3 transcript, project
 
+**Hermes session title**:
+The Hermes-owned name of a session. A Hermes-backed T3 Agent thread displays this title as a local projection rather than owning an independent name.
+_Avoid_: T3 thread name, synchronized title
+
 **Cross-gateway conversation**:
 A Hermes session that originated from the CLI or another messaging surface rather than T3 Agent.
 _Avoid_: Synced thread

docs/architecture/t3-agent.md

@@ -30,6 +30,10 @@ The compatibility project still exists internally because T3's persistence model
 
 A T3 Agent thread is backed by one Hermes session. New conversations create new Hermes sessions; a fork creates a new T3 thread and a child Hermes session. T3's stored transcript is the visible projection, while Hermes's session database remains the authoritative agent context.
 
+The Hermes session title is likewise authoritative. A Hermes-backed T3 thread's stored title is only the sidebar projection of that value, not an independently generated name. While a new session is waiting for Hermes's automatic title, the sidebar may display the first user message as a provisional label. Every successful Hermes title change—including automatic naming and `/title`—replaces that provisional label and updates the projection.
+
+A sidebar rename first updates Hermes and changes the projection only after Hermes accepts it; rejection or unavailability leaves the displayed title unchanged and surfaces the error. T3's inherited first-turn title generator must not run for Hermes-backed threads. Live Hermes title callbacks are the normal update path, while startup and reconnect reconciliation repair missed callbacks; whenever the stored projection disagrees with a titled Hermes session, Hermes wins.
+
 The interface must never silently switch the Hermes session underneath an existing T3 transcript. Lifecycle commands therefore require T3-native navigation semantics rather than unconditional command passthrough.
 
 ### Forking