diff --git a/packages/db/src/migrations/0049_flawless_abomination.sql b/packages/db/src/migrations/0049_flawless_abomination.sql
index adca835c..a48c468e 100644
--- a/packages/db/src/migrations/0049_flawless_abomination.sql
+++ b/packages/db/src/migrations/0049_flawless_abomination.sql
@@ -10,6 +10,7 @@ CREATE TABLE "issue_relations" (
 	"updated_at" timestamp with time zone DEFAULT now() NOT NULL
 );
 --> statement-breakpoint
+ALTER TABLE "issue_relations" ADD CONSTRAINT "issue_relations_type_check" CHECK ("type" IN ('blocks'));--> statement-breakpoint
 ALTER TABLE "issue_relations" ADD CONSTRAINT "issue_relations_company_id_companies_id_fk" FOREIGN KEY ("company_id") REFERENCES "public"."companies"("id") ON DELETE no action ON UPDATE no action;--> statement-breakpoint
 ALTER TABLE "issue_relations" ADD CONSTRAINT "issue_relations_issue_id_issues_id_fk" FOREIGN KEY ("issue_id") REFERENCES "public"."issues"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
 ALTER TABLE "issue_relations" ADD CONSTRAINT "issue_relations_related_issue_id_issues_id_fk" FOREIGN KEY ("related_issue_id") REFERENCES "public"."issues"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
@@ -17,4 +18,4 @@ ALTER TABLE "issue_relations" ADD CONSTRAINT "issue_relations_created_by_agent_i
 CREATE INDEX "issue_relations_company_issue_idx" ON "issue_relations" USING btree ("company_id","issue_id");--> statement-breakpoint
 CREATE INDEX "issue_relations_company_related_issue_idx" ON "issue_relations" USING btree ("company_id","related_issue_id");--> statement-breakpoint
 CREATE INDEX "issue_relations_company_type_idx" ON "issue_relations" USING btree ("company_id","type");--> statement-breakpoint
-CREATE UNIQUE INDEX "issue_relations_company_edge_uq" ON "issue_relations" USING btree ("company_id","issue_id","related_issue_id","type");
\ No newline at end of file
+CREATE UNIQUE INDEX "issue_relations_company_edge_uq" ON "issue_relations" USING btree ("company_id","issue_id","related_issue_id","type");
diff --git a/packages/db/src/schema/issue_relations.ts b/packages/db/src/schema/issue_relations.ts
index ed7a0e7f..ee0150b1 100644
--- a/packages/db/src/schema/issue_relations.ts
+++ b/packages/db/src/schema/issue_relations.ts
@@ -10,7 +10,7 @@ export const issueRelations = pgTable(
     companyId: uuid("company_id").notNull().references(() => companies.id),
     issueId: uuid("issue_id").notNull().references(() => issues.id, { onDelete: "cascade" }),
     relatedIssueId: uuid("related_issue_id").notNull().references(() => issues.id, { onDelete: "cascade" }),
-    type: text("type").notNull(),
+    type: text("type").$type<"blocks">().notNull(),
     createdByAgentId: uuid("created_by_agent_id").references(() => agents.id, { onDelete: "set null" }),
     createdByUserId: text("created_by_user_id"),
     createdAt: timestamp("created_at", { withTimezone: true }).notNull().defaultNow(),
diff --git a/server/src/services/issues.ts b/server/src/services/issues.ts
index 3bef40fa..a223e962 100644
--- a/server/src/services/issues.ts
+++ b/server/src/services/issues.ts
@@ -819,6 +819,13 @@ export function issueService(db: Db) {
     }
 
     if (deduped.length > 0) {
+      const lockedIssueIds = [issueId, ...deduped].sort();
+      await dbOrTx.execute(
+        sql`SELECT ${issues.id} FROM ${issues}
+            WHERE ${and(eq(issues.companyId, companyId), inArray(issues.id, lockedIssueIds))}
+            ORDER BY ${issues.id}
+            FOR UPDATE`,
+      );
       const relatedIssues = await dbOrTx
         .select({ id: issues.id })
         .from(issues)
diff --git a/skills/paperclip/SKILL.md b/skills/paperclip/SKILL.md
index 43a69b41..c260fa32 100644
--- a/skills/paperclip/SKILL.md
+++ b/skills/paperclip/SKILL.md
@@ -128,6 +128,8 @@ Paperclip fires automatic wakes in two scenarios:
 1. **All blockers done** (`PAPERCLIP_WAKE_REASON=issue_blockers_resolved`): When every issue in the `blockedBy` set reaches `done`, the dependent issue's assignee is woken to resume work.
 2. **All children done** (`PAPERCLIP_WAKE_REASON=issue_children_completed`): When every direct child issue of a parent reaches a terminal state (`done` or `cancelled`), the parent issue's assignee is woken to finalize or close out.
 
+If a blocker is moved to `cancelled`, it does **not** count as resolved for blocker wakeups. Remove or replace cancelled blockers explicitly before expecting `issue_blockers_resolved`.
+
 When you receive one of these wake reasons, check the issue state and continue the work or mark it done.
 
 ## Project Setup Workflow (CEO/Manager Common Path)
diff --git a/skills/paperclip/references/api-reference.md b/skills/paperclip/references/api-reference.md
index 60f02803..e9a089b2 100644
--- a/skills/paperclip/references/api-reference.md
+++ b/skills/paperclip/references/api-reference.md
@@ -189,6 +189,8 @@ The response also includes `blockedBy` and `blocks` arrays showing first-class d
 }
 ```
 
+Blocker wake semantics are strict: `issue_blockers_resolved` only fires when every blocker reaches `done`. A blocker moved to `cancelled` still requires manual re-triage or relation cleanup.
+
 ---
 
 ## Worked Example: IC Heartbeat