- V2 tool execute hooks: add `ctx.tool.execute.before/after` plugin API,
core ToolHooks service, and registry wiring so hosted/local tool calls
run registered before/after hooks; provider-executed calls are excluded.
- Session synthetic endpoint: add `POST /api/session/:sessionID/synthetic`
with text/description/metadata plus regenerated Promise/Effect/JS client
surfaces.
- SessionInstructions service: read tool discovers nearby AGENTS.md walking
up to the Location root (exclusive) and injects them as durable synthetic
instructions, with lazy history dedup of prior claims.
- to-llm-message: stop forwarding synthetic message metadata to the model so
bookkeeping annotations stay model-hidden.
- schema changelog entry for synthetic metadata and the metadata leak fix.
Add SessionTitle service that generates a session title from the
session's sole user message via the customizable "title" agent, then
renames the session. Runs once per session, gated on durable history
having exactly one user message (no default-title string comparison).
Wire it into SessionRunner as a background fork after the first turn's
prompt promotion makes the user message visible; forking before
promotion caused the first-message lookup to see zero rows and silently
no-op.
Closes#34364