diff --git a/src/resources/extensions/gsd/gsd-db.ts b/src/resources/extensions/gsd/gsd-db.ts
index 5e46dace8..e2c80063f 100644
--- a/src/resources/extensions/gsd/gsd-db.ts
+++ b/src/resources/extensions/gsd/gsd-db.ts
@@ -451,6 +451,19 @@ function migrateSchema(db: DbAdapter): void {
   const currentVersion = row ? (row["v"] as number) : 0;
   if (currentVersion >= SCHEMA_VERSION) return;
 
+  // Backup database before migration so a mid-migration crash doesn't
+  // leave a partially-migrated DB with no recovery path.
+  if (currentPath && currentPath !== ":memory:" && existsSync(currentPath)) {
+    try {
+      const backupPath = `${currentPath}.backup-v${currentVersion}`;
+      if (!existsSync(backupPath)) {
+        copyFileSync(currentPath, backupPath);
+      }
+    } catch {
+      // Non-fatal — proceed with migration even if backup fails
+    }
+  }
+
   db.exec("BEGIN");
   try {
     if (currentVersion < 2) {
@@ -999,9 +1012,21 @@ export function _resetProvider(): void {
 
 export function upsertDecision(d: Omit<Decision, "seq">): void {
   if (!currentDb) throw new GSDError(GSD_STALE_STATE, "gsd-db: No database open");
+  // Use ON CONFLICT DO UPDATE instead of INSERT OR REPLACE to preserve the
+  // seq column. INSERT OR REPLACE deletes then reinserts, resetting seq and
+  // corrupting decision ordering in DECISIONS.md after reconcile replay.
   currentDb.prepare(
-    `INSERT OR REPLACE INTO decisions (id, when_context, scope, decision, choice, rationale, revisable, made_by, superseded_by)
-     VALUES (:id, :when_context, :scope, :decision, :choice, :rationale, :revisable, :made_by, :superseded_by)`,
+    `INSERT INTO decisions (id, when_context, scope, decision, choice, rationale, revisable, made_by, superseded_by)
+     VALUES (:id, :when_context, :scope, :decision, :choice, :rationale, :revisable, :made_by, :superseded_by)
+     ON CONFLICT(id) DO UPDATE SET
+       when_context = excluded.when_context,
+       scope = excluded.scope,
+       decision = excluded.decision,
+       choice = excluded.choice,
+       rationale = excluded.rationale,
+       revisable = excluded.revisable,
+       made_by = excluded.made_by,
+       superseded_by = excluded.superseded_by`,
   ).run({
     ":id": d.id,
     ":when_context": d.when_context,
diff --git a/src/resources/extensions/gsd/state.ts b/src/resources/extensions/gsd/state.ts
index db97248f6..d484c6b13 100644
--- a/src/resources/extensions/gsd/state.ts
+++ b/src/resources/extensions/gsd/state.ts
@@ -304,12 +304,9 @@ function extractContextTitle(content: string | null, fallback: string): string {
 
 // ─── DB-backed State Derivation ────────────────────────────────────────────
 
-/**
- * Helper: check if a DB status counts as "done" (handles K002 ambiguity).
- */
-function isStatusDone(status: string): boolean {
-  return status === 'complete' || status === 'done' || status === 'skipped';
-}
+// isStatusDone replaced by isClosedStatus from status-guards.ts (single source of truth).
+// Alias kept for backward compatibility within this file.
+const isStatusDone = isClosedStatus;
 
 /**
  * Derive GSD state from the milestones/slices/tasks DB tables.
diff --git a/src/resources/extensions/gsd/workflow-events.ts b/src/resources/extensions/gsd/workflow-events.ts
index 3569bb674..efc239da5 100644
--- a/src/resources/extensions/gsd/workflow-events.ts
+++ b/src/resources/extensions/gsd/workflow-events.ts
@@ -19,10 +19,11 @@ export function getSessionId(): string {
 // ─── Event Types ─────────────────────────────────────────────────────────
 
 export interface WorkflowEvent {
-  cmd: string;           // e.g. "complete_task"
+  v?: number;              // schema version — omitted in v1 (legacy), 2 for current format
+  cmd: string;             // e.g. "complete-task" (canonical: hyphens; legacy: underscores — both accepted by replay)
   params: Record<string, unknown>;
-  ts: string;            // ISO 8601
-  hash: string;          // content hash (hex, 16 chars)
+  ts: string;              // ISO 8601
+  hash: string;            // content hash (hex, 16 chars)
   actor: "agent" | "system";
   actor_name?: string;      // e.g. "executor-agent-01" — caller-provided identity
   trigger_reason?: string;  // e.g. "plan-phase complete" — caller-provided causation
@@ -46,6 +47,7 @@ export function appendEvent(
     .slice(0, 16);
 
   const fullEvent: WorkflowEvent = {
+    v: 2,
     ...event,
     hash,
     session_id: ENGINE_SESSION_ID,
diff --git a/src/resources/extensions/gsd/workflow-projections.ts b/src/resources/extensions/gsd/workflow-projections.ts
index 15d39d55a..dfa8b170e 100644
--- a/src/resources/extensions/gsd/workflow-projections.ts
+++ b/src/resources/extensions/gsd/workflow-projections.ts
@@ -16,6 +16,7 @@ import { atomicWriteSync } from "./atomic-write.js";
 import { join } from "node:path";
 import { mkdirSync, existsSync } from "node:fs";
 import { logWarning } from "./workflow-logger.js";
+import { isClosedStatus } from "./status-guards.js";
 import { deriveState } from "./state.js";
 import type { GSDState } from "./types.js";
 
@@ -55,7 +56,7 @@ export function renderPlanContent(sliceRow: SliceRow, taskRows: TaskRow[]): stri
   lines.push("## Tasks");
 
   for (const task of taskRows) {
-    const checkbox = task.status === "done" || task.status === "complete" ? "[x]" : "[ ]";
+    const checkbox = isClosedStatus(task.status) ? "[x]" : "[ ]";
     lines.push(`- ${checkbox} **${task.id}: ${task.title}** \u2014 ${task.description}`);
 
     // Estimate subline (always present if non-empty)
@@ -125,7 +126,7 @@ export function renderRoadmapContent(milestoneRow: MilestoneRow, sliceRows: Slic
   lines.push("|----|-------|------|---------|------|------------|");
 
   for (const slice of sliceRows) {
-    const done = slice.status === "done" || slice.status === "complete" ? "\u2705" : "\u2B1C";
+    const done = isClosedStatus(slice.status) ? "\u2705" : "\u2B1C";
 
     // depends is already parsed to string[] by rowToSlice
     let depends = "\u2014";