diff --git a/.changeset/scope-listtasks-pretooluse.md b/.changeset/scope-listtasks-pretooluse.md
new file mode 100644
index 00000000..ebaa7d8f
--- /dev/null
+++ b/.changeset/scope-listtasks-pretooluse.md
@@ -0,0 +1,10 @@
+---
+'@colony/storage': patch
+'@colony/hooks': patch
+---
+
+Stop scanning the full task table on every PreToolUse tool call
+
+`protectedLiveClaimConflict` in the PreToolUse hook used `listTasks(1_000_000)` to find conflicting protected-branch claims and then linearly filtered the result by `repo_root` and `isProtectedBranch(branch)`. With the task table growing into the thousands across all agents, that scan dominated p95 latency on every editor tool call and violated the <150ms hook-handler budget.
+
+`@colony/storage` now exposes `listProtectedBranchTasksByRepo(repoRoot)`, a single index-backed query against the existing `UNIQUE(repo_root, branch)` constraint. The PreToolUse hook calls this in place of the unbounded scan; defensive `resolve()` and `isProtectedBranch()` checks remain inside the loop so storage path inconsistencies still get filtered out. No new migration is needed — the unique index already covers the new query shape.
diff --git a/packages/core/src/stranded-rescue.ts b/packages/core/src/stranded-rescue.ts
index 5d520ff5..0e596c8c 100644
--- a/packages/core/src/stranded-rescue.ts
+++ b/packages/core/src/stranded-rescue.ts
@@ -357,46 +357,49 @@ export function bulkRescueStrandedSessions(
     // subsequent deletes/writes are atomic across processes. Two concurrent
     // rescue callers could otherwise both read the same held claims outside
     // the transaction and then both attempt to release and audit them.
-    const audit_observation_id = store.storage.transaction(() => {
-      // Re-read claims inside the transaction so the set we release matches
-      // exactly what is visible under the write lock — guards against a
-      // concurrent caller having already released some of them between the
-      // outer read and this point.
-      const liveClaims = heldClaimsForCandidate(store, candidate);
-      if (liveClaims.length === 0) return -1;
-      for (const claim of liveClaims) {
-        store.storage.releaseClaim({
-          task_id: claim.task_id,
-          file_path: claim.file_path,
-          session_id,
-        });
-      }
-      const auditId = store.addObservation({
-        session_id,
-        kind: 'rescue-stranded',
-        content: `Bulk rescue released ${liveClaims.length} claim(s) for stranded session ${session_id}; audit history retained.`,
-        metadata: {
-          kind: 'rescue-stranded',
-          action: 'bulk-release-claims',
-          stranded_session_id: session_id,
-          agent: row.agent,
-          repo_root: row.repo_root,
-          branch: row.branch,
-          repo_roots: row.repo_roots,
-          branches: row.branches,
-          task_ids: row.task_ids,
-          last_activity: row.last_activity,
-          held_claim_count: liveClaims.length,
-          released_claims: liveClaims.map((claim) => ({
+    const audit_observation_id = store.storage.transaction(
+      () => {
+        // Re-read claims inside the transaction so the set we release matches
+        // exactly what is visible under the write lock — guards against a
+        // concurrent caller having already released some of them between the
+        // outer read and this point.
+        const liveClaims = heldClaimsForCandidate(store, candidate);
+        if (liveClaims.length === 0) return -1;
+        for (const claim of liveClaims) {
+          store.storage.releaseClaim({
             task_id: claim.task_id,
             file_path: claim.file_path,
-            claimed_at: claim.claimed_at,
-          })),
-        },
-      });
-      store.storage.endSession(session_id, now);
-      return auditId;
-    }, { immediate: true });
+            session_id,
+          });
+        }
+        const auditId = store.addObservation({
+          session_id,
+          kind: 'rescue-stranded',
+          content: `Bulk rescue released ${liveClaims.length} claim(s) for stranded session ${session_id}; audit history retained.`,
+          metadata: {
+            kind: 'rescue-stranded',
+            action: 'bulk-release-claims',
+            stranded_session_id: session_id,
+            agent: row.agent,
+            repo_root: row.repo_root,
+            branch: row.branch,
+            repo_roots: row.repo_roots,
+            branches: row.branches,
+            task_ids: row.task_ids,
+            last_activity: row.last_activity,
+            held_claim_count: liveClaims.length,
+            released_claims: liveClaims.map((claim) => ({
+              task_id: claim.task_id,
+              file_path: claim.file_path,
+              claimed_at: claim.claimed_at,
+            })),
+          },
+        });
+        store.storage.endSession(session_id, now);
+        return auditId;
+      },
+      { immediate: true },
+    );
 
     // -1 means another concurrent caller already released the claims before
     // this transaction acquired the write lock — skip rather than double-count.
diff --git a/packages/core/src/task-thread.ts b/packages/core/src/task-thread.ts
index 435194aa..71b7ecc8 100644
--- a/packages/core/src/task-thread.ts
+++ b/packages/core/src/task-thread.ts
@@ -1751,81 +1751,84 @@ export class TaskThread {
     // writes are serialized across processes. Without IMMEDIATE, two concurrent
     // cleanup callers both read the same expired claims in DEFERRED mode, then
     // both attempt to write — producing duplicate claim-weakened observations.
-    return this.store.storage.transaction(() => {
-      const claims = this.claims().filter((claim) => {
-        if (claim.state !== 'handoff_pending') return false;
-        if (typeof claim.expires_at !== 'number' || now < claim.expires_at) return false;
-        if (normalizedFilePath !== null && claim.file_path !== normalizedFilePath) return false;
-        if (
-          args.handoff_observation_id !== undefined &&
-          claim.handoff_observation_id !== args.handoff_observation_id
-        ) {
-          return false;
-        }
-        return true;
-      });
-      const audit_observation_ids: number[] = [];
-      const seenBatons = new Set<number>();
-      for (const claim of claims) {
-        if (claim.handoff_observation_id !== null) seenBatons.add(claim.handoff_observation_id);
-        if (claim.handoff_observation_id !== null) {
-          this.store.storage.markClaimWeakExpired({
+    return this.store.storage.transaction(
+      () => {
+        const claims = this.claims().filter((claim) => {
+          if (claim.state !== 'handoff_pending') return false;
+          if (typeof claim.expires_at !== 'number' || now < claim.expires_at) return false;
+          if (normalizedFilePath !== null && claim.file_path !== normalizedFilePath) return false;
+          if (
+            args.handoff_observation_id !== undefined &&
+            claim.handoff_observation_id !== args.handoff_observation_id
+          ) {
+            return false;
+          }
+          return true;
+        });
+        const audit_observation_ids: number[] = [];
+        const seenBatons = new Set<number>();
+        for (const claim of claims) {
+          if (claim.handoff_observation_id !== null) seenBatons.add(claim.handoff_observation_id);
+          if (claim.handoff_observation_id !== null) {
+            this.store.storage.markClaimWeakExpired({
+              task_id: this.task_id,
+              file_path: claim.file_path,
+              session_id: claim.session_id,
+              handoff_observation_id: claim.handoff_observation_id,
+            });
+          }
+          const auditObservationId = this.store.addObservation({
+            session_id: args.session_id,
+            kind: 'claim-weakened',
+            content: `claim ${claim.file_path} downgraded to weak_expired from quota-pending owner ${claim.session_id}`,
             task_id: this.task_id,
-            file_path: claim.file_path,
-            session_id: claim.session_id,
-            handoff_observation_id: claim.handoff_observation_id,
+            reply_to: claim.handoff_observation_id,
+            metadata: {
+              kind: 'claim-weakened',
+              file_path: claim.file_path,
+              previous_session_id: claim.session_id,
+              ownership_strength: 'weak',
+              state: 'weak_expired',
+              reason: 'quota_pending_expired',
+              handoff_observation_id: claim.handoff_observation_id,
+              previous_claimed_at: claim.claimed_at,
+              expires_at: claim.expires_at,
+            },
+          });
+          audit_observation_ids.push(auditObservationId);
+          recordReflexion(this.store, {
+            session_id: args.session_id,
+            task_id: this.task_id,
+            kind: 'rollback',
+            action: 'quota claim released',
+            observation_summary: `quota claim rolled back to weak_expired for task ${this.task_id}`,
+            reflection: 'expired quota claims should be weakened before another agent proceeds',
+            source_kind: 'claim-weakened',
+            source_observation_id: auditObservationId,
+            idempotency_key: `quota-release:${this.task_id}:${claim.file_path}:${claim.session_id}:${claim.handoff_observation_id ?? 'none'}`,
+            reply_to: claim.handoff_observation_id,
+            now,
+            tags: ['quota', 'claim'],
           });
         }
-        const auditObservationId = this.store.addObservation({
-          session_id: args.session_id,
-          kind: 'claim-weakened',
-          content: `claim ${claim.file_path} downgraded to weak_expired from quota-pending owner ${claim.session_id}`,
+        for (const batonId of seenBatons) {
+          this.expireQuotaBatonIfPending(batonId, now);
+        }
+        this.store.storage.touchTask(this.task_id, now);
+        return {
+          status: 'released_expired',
           task_id: this.task_id,
-          reply_to: claim.handoff_observation_id,
-          metadata: {
-            kind: 'claim-weakened',
+          released_claims: claims.map((claim) => ({
             file_path: claim.file_path,
             previous_session_id: claim.session_id,
-            ownership_strength: 'weak',
-            state: 'weak_expired',
-            reason: 'quota_pending_expired',
             handoff_observation_id: claim.handoff_observation_id,
-            previous_claimed_at: claim.claimed_at,
-            expires_at: claim.expires_at,
-          },
-        });
-        audit_observation_ids.push(auditObservationId);
-        recordReflexion(this.store, {
-          session_id: args.session_id,
-          task_id: this.task_id,
-          kind: 'rollback',
-          action: 'quota claim released',
-          observation_summary: `quota claim rolled back to weak_expired for task ${this.task_id}`,
-          reflection: 'expired quota claims should be weakened before another agent proceeds',
-          source_kind: 'claim-weakened',
-          source_observation_id: auditObservationId,
-          idempotency_key: `quota-release:${this.task_id}:${claim.file_path}:${claim.session_id}:${claim.handoff_observation_id ?? 'none'}`,
-          reply_to: claim.handoff_observation_id,
-          now,
-          tags: ['quota', 'claim'],
-        });
-      }
-      for (const batonId of seenBatons) {
-        this.expireQuotaBatonIfPending(batonId, now);
-      }
-      this.store.storage.touchTask(this.task_id, now);
-      return {
-        status: 'released_expired',
-        task_id: this.task_id,
-        released_claims: claims.map((claim) => ({
-          file_path: claim.file_path,
-          previous_session_id: claim.session_id,
-          handoff_observation_id: claim.handoff_observation_id,
-          state: 'weak_expired' as const,
-        })),
-        audit_observation_ids,
-      };
-    }, { immediate: true });
+            state: 'weak_expired' as const,
+          })),
+          audit_observation_ids,
+        };
+      },
+      { immediate: true },
+    );
   }
 
   private assertTaskExists(): void {
diff --git a/packages/core/test/claim-lifecycle-concurrency.test.ts b/packages/core/test/claim-lifecycle-concurrency.test.ts
index e773ea7e..d2abe9be 100644
--- a/packages/core/test/claim-lifecycle-concurrency.test.ts
+++ b/packages/core/test/claim-lifecycle-concurrency.test.ts
@@ -152,10 +152,7 @@ describe('releaseExpiredQuotaClaims idempotency', () => {
           handoff_observation_id?: number;
           reason?: string;
         };
-        return (
-          meta.reason === 'quota_pending_expired' &&
-          meta.handoff_observation_id === handoffId
-        );
+        return meta.reason === 'quota_pending_expired' && meta.handoff_observation_id === handoffId;
       });
     expect(weakenedAfterFirst).toHaveLength(1);
 
@@ -176,10 +173,7 @@ describe('releaseExpiredQuotaClaims idempotency', () => {
           handoff_observation_id?: number;
           reason?: string;
         };
-        return (
-          meta.reason === 'quota_pending_expired' &&
-          meta.handoff_observation_id === handoffId
-        );
+        return meta.reason === 'quota_pending_expired' && meta.handoff_observation_id === handoffId;
       });
     expect(weakenedAfterSecond).toHaveLength(1);
   });
diff --git a/packages/hooks/src/handlers/pre-tool-use.ts b/packages/hooks/src/handlers/pre-tool-use.ts
index 24b84b4e..9159b9d4 100644
--- a/packages/hooks/src/handlers/pre-tool-use.ts
+++ b/packages/hooks/src/handlers/pre-tool-use.ts
@@ -22,7 +22,6 @@ import { extractTouchedFiles, pathExtractionWarningsForToolUse } from './post-to
 
 const CLAIM_WARNING_DEBOUNCE_MS = 60_000;
 const CLAIM_BEFORE_EDIT_FALLBACK_SESSION_ID = 'colony-pre-tool-use-diagnostics';
-const ALL_TASKS_LIMIT = 1_000_000;
 const PROTECTED_BRANCHES = new Set(['main', 'dev', 'master', 'trunk']);
 const claimWarningDebounceByStore = new WeakMap<MemoryStore, Map<string, number>>();
 
@@ -433,7 +432,7 @@ function protectedLiveClaimConflict(
     const repoRoot = candidate?.repo_root ?? scope.repo_root;
     if (!repoRoot) return null;
     const normalizedRepoRoot = resolve(repoRoot);
-    const tasks = store.storage.listTasks(ALL_TASKS_LIMIT);
+    const tasks = store.storage.listProtectedBranchTasksByRepo(repoRoot);
     const conflicts: ClaimConflictInfo[] = [];
 
     for (const task of tasks) {
diff --git a/packages/storage/src/storage.ts b/packages/storage/src/storage.ts
index aad10a3e..5186bc8e 100644
--- a/packages/storage/src/storage.ts
+++ b/packages/storage/src/storage.ts
@@ -1566,6 +1566,22 @@ export class Storage {
       .all(limit) as TaskRow[];
   }
 
+  /**
+   * Tasks rooted at `repoRoot` whose `branch` is one of `PROTECTED_BRANCH_NAMES`.
+   * Backed by the existing `UNIQUE(repo_root, branch)` index on `tasks`.
+   * Used by the PreToolUse hook to detect protected-branch claim conflicts
+   * without scanning the full task table on every editor tool call.
+   */
+  listProtectedBranchTasksByRepo(repoRoot: string): TaskRow[] {
+    const names = Array.from(PROTECTED_BRANCH_NAMES);
+    const placeholders = names.map(() => '?').join(', ');
+    return this.db
+      .prepare(
+        `SELECT * FROM tasks WHERE repo_root = ? AND branch IN (${placeholders}) ORDER BY updated_at DESC`,
+      )
+      .all(repoRoot, ...names) as TaskRow[];
+  }
+
   touchTask(id: number, ts = Date.now()): void {
     this.db.prepare('UPDATE tasks SET updated_at = ? WHERE id = ?').run(ts, id);
   }
diff --git a/packages/storage/test/tasks.test.ts b/packages/storage/test/tasks.test.ts
index 9699bb1e..52e324d4 100644
--- a/packages/storage/test/tasks.test.ts
+++ b/packages/storage/test/tasks.test.ts
@@ -466,6 +466,46 @@ describe('tasks', () => {
 
     expect(storage.getClaim(task.id, 'src/x.ts')).toMatchObject({ state: 'weak_expired' });
   });
+
+  it('listProtectedBranchTasksByRepo returns only tasks on protected branches at the given repo', () => {
+    seedSessions('s-a');
+    const targetMain = storage.findOrCreateTask({
+      title: 'main lane',
+      repo_root: '/repo-a',
+      branch: 'main',
+      created_by: 's-a',
+    });
+    const targetDev = storage.findOrCreateTask({
+      title: 'dev lane',
+      repo_root: '/repo-a',
+      branch: 'dev',
+      created_by: 's-a',
+    });
+    storage.findOrCreateTask({
+      title: 'agent lane same repo',
+      repo_root: '/repo-a',
+      branch: 'agent/claude/feature',
+      created_by: 's-a',
+    });
+    storage.findOrCreateTask({
+      title: 'main lane different repo',
+      repo_root: '/repo-b',
+      branch: 'main',
+      created_by: 's-a',
+    });
+    for (let i = 0; i < 25; i++) {
+      storage.findOrCreateTask({
+        title: `noise ${i}`,
+        repo_root: '/repo-a',
+        branch: `agent/claude/noise-${i}`,
+        created_by: 's-a',
+      });
+    }
+
+    const rows = storage.listProtectedBranchTasksByRepo('/repo-a');
+    const ids = rows.map((row) => row.id).sort((a, b) => a - b);
+    expect(ids).toEqual([targetMain.id, targetDev.id].sort((a, b) => a - b));
+  });
 });
 
 function rewriteTaskClaimsAsOldSchema(dbPath: string): void {