Study AP · Agent-surface steering
The off-catalog fork: one sentence settles the foreign branch; the registration loses the adjacent one
The off-catalog fork
Study Overview
The Fork AO Filed
Study AO ended with a protocol lesson: its non-empty "clean" definition mis-scored opus declining to tag off-catalog topics. AP registered that fork explicitly, splitting the old uncovered class into adjacent (a general canonical tag genuinely fits) and foreign (nothing does), and measured two candidate guidance sentences plus a guarded tag_create tool: 48 tasks, four arms, three models, 576 cells.
The Foreign Branch Settles
Unaided, the frontier tier already refuses: opus returned empty tag lists on 12/12 wholly-foreign topics, replicating AO exactly, while gemini and sonnet stretched general canonical tags onto 5 of 12. Either guidance sentence closes that gap. The minimal empty text ("if no canonical tag genuinely fits, return an empty tags list") hit 12/12 on all three models, and its feared side effect, suppressing legitimate tags on adjacent topics, never appeared: zero empty adjacent cells in any arm on any model.
The Tool Is Discipline-Safe, With a Tier Map
With a guarded tag_create in hand, no model produced a single invented tag in 144 tool-arm cells, and the server-side guard never fired: all 40 mints were well-formed, Title Case, and free of near-duplicates. Willingness split sharply by tier: gemini minted on every foreign topic (26 mints), sonnet 10, opus 4; the frontier tier prefers empty over minting. A sub-frontier agent grows the catalog by a dozen well-formed, unwanted tags per batch, so if the tool ships it ships tier-gated or with human approval on new tags.
The Gate Failed on the Registration
The pre-registered gate failed by the letter: opus cleared 8/12 adjacent cells under the fork text against a ≥10 bar. The audit shows every failing cell was all-canonical; the misses are one or two extra, editorially arguable tags beyond the solo-authored acceptable sets (UX on a checkout-conversion piece, CSS on web components, Security on email deliverability). Under an anchored reading (all tags canonical, at least one from the registered set) adjacent scores 144/144 across every model and arm; that number is published as exploratory, not the registered definition. AO's lesson recurred one class over: acceptance criteria authored alone under-cover defensible editorial judgment.
What Ships and What Waits
Nothing ships from a failed gate. Filed: AP′, which re-registers the adjacent conformance definition and re-scores the same frozen raw results with no new API spend; the guidance-text decision waits for it. The foreign branch does not wait: on registered gates, either sentence stops sub-frontier stretching onto wholly-foreign topics, and the frontier tier never needed the help.