tidy setup: retire effect-op-arg-modes bundle; split out effect-doc-honesty + AILang-code spec discipline

The effect-op-arg-modes brainstorm spec bundled a real, self-contained
DESIGN.md honesty fix with speculative build-ahead infra (an EffectOpSig
arg-mode field whose only consumer was a synthetic test op). Recon had
already destroyed the "effect-handler infrastructure" premise: the effect
raise/declare/subset/propagation machinery is fully generic over any
effect string; the only real prerequisite was one struct field, not a
milestone. The user rejected the bundle as incoherent and the
build-ahead half as the iteration-discipline trap repeated.

- Retire the uncommitted effect-op-arg-modes spec (deleted from the
  working tree; never committed).
- roadmap: drop the false "sub-ms-2 = effect-handler infrastructure"
  framing; mark Stateful-islands sub-milestone sequencing as UNDER
  RE-THINK with the user (no !Mut planning until that conversation);
  add the split-out effect-doc-honesty as an in-flight P2 [~] todo.
- plan docs/plans/2026-05-16-effect-doc-honesty.md: placeholder-free
  tidy plan (the three DESIGN.md fictions + form_a.md + main.rs +
  a new doc-presence pin) over recon-mapped exact byte sites.
- brainstorm SKILL: specs and design talk LEAD with the AILang (.ail)
  program that should work (= the feature-acceptance clause-1
  evidence); the Rust implementation shape is secondary, never a
  substitute; a no-surface infra milestone still shows concrete .ail
  (often a must-fail fixture). Codifies user feedback from this session.

docs/roadmap.md

@@ -221,6 +221,33 @@ clean. Pick the next milestone from P2.)_
 - [ ] **\[todo\]** 21'h iteration — final 21' carry-over (latency
   methodology pass). Numbering kept for continuity with the 21' arc.
 
+- [~] **\[todo\]** DESIGN.md effect-prose is fiction — standalone
+  documentation-honesty tidy (split out 2026-05-16 from the rejected
+  effect-op-arg-modes bundle; in flight via planner→implement). Three
+  load-bearing effect-system claims in DESIGN.md are presently false
+  and mislead every future brainstorm + the architect, who read
+  DESIGN.md as truth: (a) DESIGN.md:172/2722 say `IO` **and**
+  `Diverge` are wired-up built-in ops — `Diverge` has zero code in
+  any crate (not registered, never injected, no string literal);
+  reconcile to "only `IO` (`io/print_str`) is wired up; `Diverge`
+  reserved/unimplemented", modelled on Decision 4's
+  reserved-but-opaque refinements precedent. (b) DESIGN.md:171-172
+  "the effect set is row-polymorphic (`![IO | r]`)" — no row variable
+  / `EffectRow` exists anywhere; effect sets are flat string
+  collections unified by set-equality; remove the claim (a flat
+  closed set is *more* locally legible — Decision 3 pillar — so this
+  is honesty, not a concession; pillar-doc edit, flag at review).
+  (c) `crates/ailang-core/src/ast.rs:438-439` `Term::Do` doc-comment
+  "resolved against the effect-handler table at link time" — there is
+  no handler table; it is an `IndexMap` lookup at typecheck + a
+  literal codegen `match`; correct it. Lockstep: `form_a.md:226,358`
+  + CLI-help `main.rs:289` Diverge mentions reconciled. Guard: a new
+  doc-presence test (false strings absent, corrected text present).
+  No language/codegen change; pure documentation truth. Grounding
+  triple-verified 2026-05-16 (three `ailang-grounding-check` PASSes).
+  - context: surfaced by the effect-subsystem recon during the
+    retired effect-op-arg-modes brainstorm; see the Stateful-islands
+    "UNDER RE-THINK" note for why the bundle was rejected.
 - [ ] **\[todo\]** `io/print_float` always-emit-`.0` — surface
   printer always emits `.` or `e/E` so re-lex routes to Float;
   the runtime printer (`printf("%g\n", v)`) doesn't, so `2.0`
@@ -330,13 +357,35 @@ clean. Pick the next milestone from P2.)_
   fn signatures stay pure while LLM authors can write imperative
   accumulators directly. Spec `docs/specs/2026-05-15-mut-local.md`;
   iters mut.1/mut.2/mut.3/mut.4-tidy (commits 7b92719, b24718a,
-  03fb633, 20add51). Remaining sub-milestones (to be brainstormed
-  separately, in order): (2) effect-handler infrastructure as a
-  prerequisite for any non-IO/non-Diverge effect; (3) `!Mut` effect
-  + `ref a` first-class type that can escape mut blocks under
-  uniqueness-tracking; (4) mutable-array primitive `MutArray a`;
-  (5) `Stateful a b` sealed callable type + `pipe` combinator with
-  zero-allocation composition + `runST`-equivalent escape discharge.
+  03fb633, 20add51).
+
+  **Sub-milestone sequencing is UNDER RE-THINK with the user
+  (2026-05-16) — no further sub-milestone is planned or brainstormed
+  until that conversation happens.** Why: the 2026-05-15 decomposition
+  named "(2) effect-handler infrastructure as a prerequisite for any
+  non-IO/non-Diverge effect" as the next step. A read-only recon of
+  the live effect subsystem (2026-05-16) showed that premise is false:
+  the effect raise / declared-set / `UndeclaredEffect`-subset / call-
+  propagation machinery is already fully generic over an arbitrary
+  effect string; `!Mut` needs **no** effect-handler machinery. The
+  only real code prerequisite the recon found is one hard-coded
+  assumption (`linearity.rs` walks every `Term::Do` arg as `Borrow`;
+  `EffectOpSig` has no per-arg mode field) — a single struct field,
+  not a milestone. A brainstorm spec that tried to make sub-ms-2 a
+  standalone deliverable bundled that speculative one-field capability
+  with an unrelated DESIGN.md honesty fix; the user correctly rejected
+  the bundle as incoherent and the build-ahead-of-consumer half as the
+  iteration-discipline trap repeated. **Resolution:** (a) the DESIGN.md
+  effect-honesty correction is split out and runs now as a standalone
+  documentation tidy (see the P2 `[todo]` "DESIGN.md effect-prose is
+  fiction" below); (b) the `arg_modes` finding is recorded as recon
+  context for the future `!Mut` design, NOT built ahead — it is
+  first-iteration material of whatever the `!Mut` milestone turns out
+  to be, validated there against a real consuming op, never a
+  synthetic test op; (c) the old "(2)…(5)" sequence (effect-handler
+  infra → `!Mut`+`ref a` → `MutArray a` → `Stateful a b`+`pipe`) is
+  no longer treated as settled — the whole ordering and granularity
+  is what the pending user conversation re-decides.
 
   **Motivation.** AILang's signature-as-contract thesis is *better*
   served by an explicit `Stateful a b` + `!Mut` annotation than by