Function generate_definition_activity_summary 

pub(crate) async fn generate_definition_activity_summary(
    mstore: &Store,
    filestore: &FileStore,
    broker: &Arc<Broker>,
    definition_id: &str,
    block_id: &str,
    provider_id: &str,
) -> Option<Generated>

Generate (and persist) a short activity summary for a definition whose AgentPicker row has no structured output.state.json conversation snapshot to preview — legacy rows predating snapshot persistence, per has_snapshot in agent_handlers::session::listrecentsessions. Built from the instance’s raw terminal capture (the "output" filestore file, written unconditionally by the CLI pipeline, independent of the newer structured snapshot), reusing read_recent_activity_digest — the same extraction generate_recovered_title above uses.

One-shot per definition, not per-turn: generation is always the constant 1, mirroring generate_subagent_name’s cache-once posture — the caller only invokes this when agent_activity_summary_get found nothing persisted yet, so there is no “newer turn” to supersede an in-flight call here (unlike the session:activity_summary RPC, which regenerates every turn for a LIVE conversation).

CLI path resolution (reagent P1, PR #2786): the row shape this feature actually targets is a CLOSED pane — DeleteBlock (sagas::delete_block::run) removes the Block row entirely on pane close while the instance row and raw filestore output survive. For such rows there is no live block to read cmd/cmd:env meta from at all, so this prefers the block record when it still exists (richer: carries the per-block auth env the CLI needs) and falls back to resolve_provider_cli_path_readonly + an EMPTY auth env otherwise — best-effort: a provider that needs per-block injected credentials (no ambient/global login available) fails the Haiku call cleanly (None, same as any other unresolvable case here), not a wrong result.

Fire-and-forget by design: the caller (listrecentsessions) spawns this in the background and does not await it inline. The row that triggered generation still shows its existing fallback text on THIS response; on success this broadcasts agents:changed, which MyAgentsList.tsx already refetches on, picking up the now-persisted summary on the next load. Returns None (nothing persisted, nothing broadcast) when there’s no raw output to summarize, the CLI path isn’t resolvable, this call was superseded/capped, or the CLI failed — the caller treats all of these as “still nothing to show,” not an error.