docs: close out C4 — all routes landed, with the four owed gates and the process findings

C4's route work is complete. Records the landings, corrects the campaign
plan's now-false claims, updates the roadmap, and writes the successor
handoff at docs/research/2026-08-05-c4-closeout-handoff.md.

Routes, with review rounds and gate status:
  4a    44830a0e   |  4b-1  2e8e09ac
  4b-3  6dc7ba51   2 rounds; gate PASSED-partial (21cd6e9b), cellless unexercised
  5     36255af0   3 rounds, 8 MAJORs; NO live gate possible by design
  6     1b484937   zero production lines; its tests found #314
  7     cd3129e9   2 rounds + a required third pass, 5 MAJORs
  3     e0f96a55   3 rounds; found a 100%-dead production path
plus edc911b0 (the OnPosition dual-tail collapse), aaf0811f (#315),
daef7c98 (#314), a89bcb39 (#316 filed).

Suite 11,027 -> 11,090 passed / 4 skipped / 0 failed. Every checkpoint
0-failed; no test weakened, no Skip introduced.

FOUR CONNECTED GATES ARE OWED and none has been run. Each is recorded with
its recipe and a probe-gated pass criterion, because a clean-looking session
is not a pass: route 6 drops; route 7 equip/carry with
ACDREAM_PROBE_CHILD_CELL=1 (counts only if cause=propagate appears); route 3
portal/recall with ACDREAM_PROBE_LOCAL_TELEPORT=1 (counts only if [local-tp]
appears, and is explicitly NOT scored as covering #318); and 4b-3's
cause=cellless case — whose recorded recipe route 7 INVALIDATED, since
unwield-to-3D no longer yields a cell-less pre-merge cell. Its replacement
trigger is stated as UNESTABLISHED rather than guessed.

Campaign-plan corrections beyond the C4 section, all found by checking
against HEAD rather than trusting the text:
  - "six fixture failures ... classify before C5" — resolved as #281, and
    "six" was a mis-measurement; the measured baseline was 43.
  - "fold in #276 and #277" — #276 only partially (projectile half); #277 not
    at all, its trigger never fired.
  - "#269 slope-glide visual check" — #269 was closed 2026-07-31, BEFORE the
    plan was written. The surviving item is #278(b).
  - the 4b-2 bullet's "Still outstanding: #309" — re-scoped 2026-08-04;
    only the GotoLostCell half survives.

Seven process findings, each cited to a commit so a successor can check them:
  (a) THE CONTRACT CAUSES THE DEFECT — three defects this campaign came from
      a contract asserting a mechanism that did not exist; route 3's "Place
      re-fires" assumption released the player at the pre-teleport position.
      Route 7 adds the variant: enter_cell's part_array guard was correctly
      called load-bearing by the research, dropped by the contract, and
      inherited as an omission by the code — a right finding that evaporated
      across two handoffs with nobody re-reading the source.
  (b) INFERRING A FACT YOU CAN OBSERVE IS HOW A FIX GOES SILENT — route 3's
      round-2 fix inferred "committed" from a global PendingCount that three
      non-committing paths also clear, so the same bug completed cleanly and
      PASSED its invariant. Strictly worse than the defect it replaced.
  (c) PLANNING DOCS GO STALE ACROSS CUTOVERS — at least five were wrong
      against HEAD. Re-verify by symbol, never by line number; route 3's
      by-symbol sweep proved only 2 of 5 flagged files actually intersected.
  (d) A SKIPPED TEST IS A PERMANENT FALSE SIGNAL — refusing 7 skips uncovered
      a production bug that had made the entire portal arm dead code.
  (e) SABOTAGE-VERIFY, AND WATCH FOR TESTS READING A CONSTANT THEY PERTURB —
      one built a 64,000-node chain and stack-overflowed the host; another
      survived deleting the whole behaviour it claimed to pin, because its
      assertion read a field written unconditionally one line earlier.
  (f) REVIEWERS RETRACT, AND THAT IS THE PROCESS WORKING — three self-
      retractions, two of which prevented shipping a wrong register row or a
      relocated defect.
  (g) A GATE MUST BE ABLE TO SEE THE DEFECT IT GATES — three gates were
      unpassable or blind as specified and were corrected BEFORE being run.

Issues: #313, #316, #317, #318 open; #314, #315 closed. Register rows AP-141
through AP-145 added; AD-42 deleted, AD-2 amended.

C5 inherits #318's composition test (discriminating assertion:
PhysicsEngine.ShadowObjects must hold a row at the destination, not merely
the dedup cache), AP-145's cache-without-publish asymmetry, the #276/#277
remainders, and the probe-family strip.

Three things the closeout could NOT verify are stated as such rather than
smoothed: route 3 has no standalone round-3 review document (acceptance lives
in e0f96a55's message and both round-2 pass conditions); route 7's round
terminology differs across its own artifacts; and route 6's lack of dual
reviews is inferred from absent review docs, not stated anywhere.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docs/ISSUES.md

@@ -1417,8 +1417,9 @@ it. Do #297 FIRST — #298 depends on it.
   stalled streaming and portal convergence is gone (`01f4791e`); and (f)
   materialization/effect presentation is bound after canonical placement
   (`f24532ad`, `175ad6b0`). The remaining item is (b): explicitly compare
-  lateral glide against impassable slopes with open #269 before closing this
-  bundle. Far terrain that can visibly continue building after portal reveal
+  lateral glide against impassable slopes before closing this bundle (the
+  original wording said "with open #269", but #269 was already DONE
+  2026-07-31 — the comparison itself is what survives). Far terrain that can visibly continue building after portal reveal
   is tracked separately as #280.
 - **#279 — DONE (2026-08-03, user-verified) — one-shot spell/effect
   scripts arriving during the suppressed-until-receipt window were lost.**