(adr-prompt-guided-conversation-routing)= # ADR 0021: Prompt-guided conversation routing ## Status Accepted. Targeted routing is implemented. ## Context Targeted search needs to reach useful conversations without treating every prompt hit as a final result or falling back to an exhaustive transcript walk. The router therefore needs a private, deterministic work-selection contract with bounded locator traversal and clear failure behavior. ## Decision Targeted routing first reads dedicated prompt-history sources. Positive text clues, or positive conversation-invariant metadata, may select candidates. Negated terms never establish routing evidence. Invariant agent and project predicates run before grouping and before the request bound. Candidates are grouped by adapter-proven native conversation identity and ordered deterministically by newest prompt evidence. The router selects at most `conversation_limit` grouped candidates, then resolves only exact provider-owned conversation locators. The default is 25 attempts. It is an unmeasured routing policy, independent of the result `limit`; no result-limit migration to 25 occurred. An ambiguous, stale, unreadable, unresolved, or locator-budget-exhausted selected candidate consumes its attempt. The router never backfills from a later candidate. Prompt-evidence read failures fail closed. Locator traversal is request-bounded, and a supported provider may share one bounded walk among its selected candidates. The router opens only uniquely proof-resolved conversation sources. Candidate identities, locators, and paths remain private engine state: they are not records, cursors, continuation tokens, or durable index contracts. Routing evidence never establishes a result match; selected conversations go through the ordinary matcher, ordering, dedupe, and limit stages. ## Consequences Targeted results can be cheaper than exhaustive search while retaining a clear coverage boundary. Their summaries report eligible, selected, and completed conversations plus privacy-safe routing diagnostics. Because candidate selection can omit a conversation, targeted completion is approximate even when every selected conversation completes. {ref}`ADR 0020 ` owns when targeted effort is selected. {ref}`ADR 0004 ` owns the shared planner, driver, matcher, collector, lifecycle, and coverage boundaries.