docs(18): create gap-closure plan 18-04

.planning/STATE.md

@@ -4,13 +4,13 @@ milestone: v3.0
 milestone_name: Phishing Triage Automation
 status: executing
 stopped_at: Phase 18 planned, 3 plans ready
-last_updated: "2026-07-15T23:14:09.528Z"
-last_activity: 2026-07-15 -- Phase 18 execution started
+last_updated: "2026-07-16T02:22:05.897Z"
+last_activity: 2026-07-16 -- Phase 18 planning complete
 progress:
   total_phases: 7
   completed_phases: 3
-  total_plans: 10
-  completed_plans: 7
+  total_plans: 11
+  completed_plans: 10
   percent: 43
 ---
 
@@ -27,8 +27,8 @@ See: .planning/PROJECT.md (updated 2026-07-14)
 
 Phase: 18 (campaign-grouping-phishing-analysis-api) — EXECUTING
 Plan: 1 of 3
-Status: Executing Phase 18
-Last activity: 2026-07-15 -- Phase 18 execution started
+Status: Ready to execute
+Last activity: 2026-07-16 -- Phase 18 planning complete
 
 Progress: [░░░░░░░░░░] 0%
 
@@ -96,7 +96,7 @@ None yet.
 
 ### Blockers/Concerns
 
-None yet.
+- 2026-07-15 — Phase 18 gap closure (18-04): decision-coverage gate flagged D-02/D-03/D-04 (grouping-parameter decisions from original discuss-phase) as not literally cited in any plan's `must_haves`/`truths`. Overridden and proceeded — these decisions were already implemented in 18-01 (24h window, subject normalization, no-merge behavior) and independently confirmed correct by both 18-REVIEW.md and 18-VERIFICATION.md. Citation gap only, not an implementation gap.
 
 ### Quick Tasks Completed