radar: pass 5 — api.sx x6 rejected (shared name, divergent state contract); filename census, no new gate-clearer

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plans/abstractions.md

@@ -12,7 +12,12 @@ Anything short → _Watching_ (what's missing) or _Rejected_ (why).
 
 ## Last scan
 
-- **Date:** 2026-06-06 (radar loop, pass 4)
+- **Date:** 2026-06-06 (radar loop, pass 5)
+- **Pass 5:** search (+highlight/snippet) and fed-sx-m1 (+follower_graph) moved; rest
+  unchanged. Filename census: `api`×6, `fed`×3, then `schema/rank/query/page/explain/
+  engine/batch/audit`×2. Examined the ×6 `api.sx` → Rejected (shared name, divergent
+  structure incl. implicit-vs-explicit-state contract). rank/batch/engine all ≤2 +
+  substrate/domain-divergent → no new gate-clearer.
 - **Pass 4:** no churn vs pass 3 (same worktrees/tmux/HEADs/adopters). Swept audit+explain
   surfaces: acl/mod share an append-only-log shape (→ sharpened W4 with persist/log API
   evidence) and a proof-explain shape (→ new W5, substrate-bound). No new gate-clearer.
@@ -165,6 +170,15 @@ Anything short → _Watching_ (what's missing) or _Rejected_ (why).
   agent writing across `lib/<x>/**` breaks the worktree isolation that makes the
   fleet safe, and is rewarded for manufacturing premature/wrong abstractions. The
   radar is read-only by design. (This file is the alternative.)
+- **Shared `api.sx` "public boundary" module (×6).** Rejected pass 4-5: every subsystem
+  has an `api.sx` (acl, feed, flow, mod, persist, search — a 100% filename match), but it
+  is a naming *convention for the public entry point*, not a shared structure. They
+  disagree on the most basic contract: acl/feed use **implicit module state**
+  (`acl/api.sx` "implicit current db", `feed/api.sx` "single mutable log") while
+  `persist/api.sx` threads an **explicit backend as every call's first arg**; flow's api
+  *builds a Scheme env*, search's api *concatenates a Haskell source string*, mod's is a
+  *lifecycle state-machine façade* (17 defs vs persist's 1). Same role, no common shape —
+  the W1 coincidental-resemblance trap. Do not re-propose on the filename.
 - **Dumping app-domain plumbing into `lib/guest`.** Rejected: `lib/guest` is for
   language-implementation plumbing. App patterns route to acl/fed-sx/persist/
   substrate/host instead (see the routing rule in the briefing).