diff --git a/.planning/STATE.md b/.planning/STATE.md
index 3a11f40a1..8ea2ffdce 100644
--- a/.planning/STATE.md
+++ b/.planning/STATE.md
@@ -20,18 +20,18 @@
 ## Current Position
 
 Phase: 16 of 16 (Plan Verification Loop)
-Plan: 0 of 3 in current phase
-Status: Planned
-Last activity: 2026-01-16 - Phase 16 planned (3 plans in 2 waves)
+Plan: 1 of 3 in current phase
+Status: In progress
+Last activity: 2026-01-16 - Completed 16-01-PLAN.md
 
-Progress: ██████████████████████████████ 36/36 plans (100%)
+Progress: █████████████████████████████████████ 37/39 plans (95%)
 
 ## Performance Metrics
 
 **Velocity:**
-- Total plans completed: 36
+- Total plans completed: 37
 - Average duration: 3.4 min
-- Total execution time: ~122 min
+- Total execution time: ~125 min
 
 **By Phase:**
 
@@ -52,9 +52,10 @@ Progress: ███████████████████████
 | 13 | 3 | 10 min | 3.3 min |
 | 14 | 3 | 11 min | 3.7 min |
 | 15 | 3 | 7 min | 2.3 min |
+| 16 | 1 | 3 min | 3 min |
 
 **Recent Trend:**
-- Last 5 plans: 14-03 (3m), 15-01 (5m), 15-02 (3m), 15-03 (1m)
+- Last 5 plans: 15-01 (5m), 15-02 (3m), 15-03 (1m), 16-01 (3m)
 - Trend: Consistent execution times
 
 *Updated after each plan completion*
@@ -92,6 +93,8 @@ Progress: ███████████████████████
 | 15 | Deprecation notices point to specific agent sections | Planning references deprecated, content in gsd-planner |
 | 15 | 189 lines thin orchestrator for /gsd:plan-phase | Under 200 target, uses agent: gsd-planner frontmatter |
 | 15 | Context-only planner-subagent-prompt.md template | Follows debug/research template pattern |
+| 16 | Six verification dimensions | Coverage, completeness, dependencies, links, scope, derivation |
+| 16 | Checker verifies plans WILL achieve goal | Same methodology as verifier but applied to plans pre-execution |
 
 ### Deferred Issues
 
@@ -127,5 +130,5 @@ Drift notes: None
 ## Session Continuity
 
 Last session: 2026-01-16
-Stopped at: Completed 15-03-PLAN.md
+Stopped at: Completed 16-01-PLAN.md
 Resume file: None
diff --git a/.planning/phases/16-plan-verification-loop/16-01-SUMMARY.md b/.planning/phases/16-plan-verification-loop/16-01-SUMMARY.md
new file mode 100644
index 000000000..925732cf7
--- /dev/null
+++ b/.planning/phases/16-plan-verification-loop/16-01-SUMMARY.md
@@ -0,0 +1,102 @@
+---
+phase: 16-plan-verification-loop
+plan: 01
+subsystem: agents
+tags: [verification, planning, goal-backward, plan-checker]
+
+# Dependency graph
+requires:
+  - phase: 15-dedicated-planner-agent
+    provides: gsd-planner agent to create plans
+provides:
+  - gsd-plan-checker agent for plan verification before execution
+  - Six verification dimensions (coverage, completeness, dependencies, links, scope, derivation)
+  - Structured issue format for planner feedback loop
+affects: [16-plan-verification-loop, plan-phase, execute-phase]
+
+# Tech tracking
+tech-stack:
+  added: []
+  patterns:
+    - "Goal-backward plan verification (plans, not code)"
+    - "Structured issue reporting with fix hints"
+    - "Checker role mirrors verifier (verify plans vs verify code)"
+
+key-files:
+  created:
+    - agents/gsd-plan-checker.md
+  modified: []
+
+key-decisions:
+  - "Six dimensions: coverage, completeness, dependencies, links, scope, derivation"
+  - "Structured YAML issue format for planner consumption"
+  - "Checker returns passed or issues_found status"
+
+patterns-established:
+  - "Plan checker verifies BEFORE execution (vs verifier verifies AFTER)"
+  - "Same goal-backward methodology as gsd-verifier but applied to plans"
+
+# Metrics
+duration: 3min
+completed: 2026-01-16
+---
+
+# Phase 16 Plan 01: Create gsd-plan-checker Agent Summary
+
+**Goal-backward plan verification agent with six dimensions: coverage, completeness, dependencies, links, scope, and derivation**
+
+## Performance
+
+- **Duration:** 3 min
+- **Started:** 2026-01-16T14:54:04Z
+- **Completed:** 2026-01-16T14:56:57Z
+- **Tasks:** 2
+- **Files modified:** 1
+
+## Accomplishments
+
+- Created gsd-plan-checker agent with complete plan verification methodology
+- Six verification dimensions covering all aspects of plan quality
+- Structured issue format that planner can consume for revisions
+- Four example scenarios demonstrating common failure modes
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1+2: Create gsd-plan-checker with examples** - `47eab1a` (feat)
+   - Combined task: created agent with all sections including examples
+
+**Plan metadata:** (pending)
+
+## Files Created/Modified
+
+- `agents/gsd-plan-checker.md` - Plan verification agent (744 lines)
+
+## Decisions Made
+
+- **Six verification dimensions:** Coverage, completeness, dependencies, key links, scope, derivation - comprehensive without overlap
+- **Structured YAML issues:** Format allows planner to programmatically parse and address
+- **Checker vs Verifier distinction:** Clear - checker verifies plans WILL achieve goal, verifier verifies code DID achieve goal
+
+## Deviations from Plan
+
+None - plan executed as written (Task 2's examples section was included in Task 1 creation for efficiency).
+
+## Issues Encountered
+
+None
+
+## User Setup Required
+
+None - no external service configuration required.
+
+## Next Phase Readiness
+
+- gsd-plan-checker agent ready for integration
+- Next: 16-02 updates plan-phase.md orchestrator to spawn checker after planner
+- Next: 16-03 adds revision mode to gsd-planner for handling checker feedback
+
+---
+*Phase: 16-plan-verification-loop*
+*Completed: 2026-01-16*