diff --git a/.changeset/reset-idempotency-key-64-char.md b/.changeset/reset-idempotency-key-64-char.md
new file mode 100644
index 0000000000..b203043a48
--- /dev/null
+++ b/.changeset/reset-idempotency-key-64-char.md
@@ -0,0 +1,5 @@
+---
+"@trigger.dev/core": patch
+---
+
+`idempotencyKeys.reset()` now works when your idempotency key is itself 64 characters long (for example if you use a hash of your own as the key). Previously any 64-character key was assumed to be already hashed, so passing one along with a `scope` silently ignored the scope and the reset never found a matching run. Keys returned by `idempotencyKeys.create()` continue to be reset exactly as before.
diff --git a/packages/core/src/v3/idempotencyKeys.test.ts b/packages/core/src/v3/idempotencyKeys.test.ts
index f511a85f86..7c9a8a9cf2 100644
--- a/packages/core/src/v3/idempotencyKeys.test.ts
+++ b/packages/core/src/v3/idempotencyKeys.test.ts
@@ -1,9 +1,15 @@
-import { describe, it, expect } from "vitest";
+import { createServer, type Server } from "node:http";
+import type { AddressInfo } from "node:net";
+import { afterEach, beforeEach, describe, expect, it } from "vitest";
+import { apiClientManager } from "./apiClientManager-api.js";
 import {
   createIdempotencyKey,
   getIdempotencyKeyOptions,
+  makeIdempotencyKey,
+  resetIdempotencyKey,
   resetIdempotencyKeyCatalog,
 } from "./idempotencyKeys.js";
+import { digestSHA256 } from "./utils/crypto.js";
 
 describe("idempotencyKeys metadata retention", () => {
   it("retains key/scope options for every key created in a run, even beyond 1000", async () => {
@@ -40,3 +46,254 @@ describe("idempotencyKeys metadata retention", () => {
     expect(getIdempotencyKeyOptions(key)).toBeUndefined();
   });
 });
+
+describe("resetIdempotencyKey", () => {
+  const digestShapedKey = "a".repeat(64);
+
+  let server: Server;
+  let resetKeys: string[] = [];
+  /** Keys the server has runs for. `undefined` means "accept every key". */
+  let existingKeys: Set<string> | undefined;
+  /** Per-key failure statuses, applied before the existence check. */
+  let statusByKey: Map<string, number>;
+
+  function notFoundMessage(key: string) {
+    return `No runs found with idempotency key: ${key}`;
+  }
+
+  async function resetAndCaptureKey(
+    ...args: Parameters<typeof resetIdempotencyKey>
+  ): Promise<string> {
+    resetKeys = [];
+    await resetIdempotencyKey(...args);
+    expect(resetKeys).toHaveLength(1);
+    return resetKeys[0]!;
+  }
+
+  beforeEach(async () => {
+    resetIdempotencyKeyCatalog();
+    resetKeys = [];
+    existingKeys = undefined;
+    statusByKey = new Map();
+
+    server = createServer((req, res) => {
+      req.resume();
+      req.on("end", () => {
+        const match = /^\/api\/v1\/idempotencyKeys\/(.+)\/reset$/.exec(req.url ?? "");
+        if (!match) {
+          res.writeHead(404).end();
+          return;
+        }
+
+        const key = decodeURIComponent(match[1]!);
+        resetKeys.push(key);
+
+        const failWith = statusByKey.get(key);
+        if (failWith !== undefined) {
+          res.writeHead(failWith, { "content-type": "application/json" });
+          res.end(JSON.stringify({ error: `request failed for ${key}` }));
+          return;
+        }
+
+        if (existingKeys !== undefined && !existingKeys.has(key)) {
+          res.writeHead(404, { "content-type": "application/json" });
+          res.end(JSON.stringify({ error: notFoundMessage(key) }));
+          return;
+        }
+
+        res.writeHead(200, { "content-type": "application/json" });
+        res.end(JSON.stringify({ id: "run_reset" }));
+      });
+    });
+
+    await new Promise<void>((resolve) => {
+      server.listen(0, "127.0.0.1", () => resolve());
+    });
+
+    apiClientManager.setGlobalAPIClientConfiguration({
+      baseURL: `http://127.0.0.1:${(server.address() as AddressInfo).port}`,
+      accessToken: "tr_test_key",
+    });
+  });
+
+  afterEach(async () => {
+    apiClientManager.disable();
+    resetIdempotencyKeyCatalog();
+    await new Promise<void>((resolve) => server.close(() => resolve()));
+  });
+
+  it("hashes 64-character key material when an explicit scope is passed", async () => {
+    const created = await createIdempotencyKey(digestShapedKey, { scope: "global" });
+
+    // The reset can happen in a different process from the trigger
+    resetIdempotencyKeyCatalog();
+
+    expect(await resetAndCaptureKey("my-task", digestShapedKey, { scope: "global" })).toBe(created);
+  });
+
+  it("hashes 64-character key material for run scope when an explicit scope is passed", async () => {
+    const parentRunId = "run_abc123";
+    const expected = await digestSHA256(`${digestShapedKey}-${parentRunId}`);
+
+    expect(
+      await resetAndCaptureKey("my-task", digestShapedKey, { scope: "run", parentRunId })
+    ).toBe(expected);
+  });
+
+  it("sends a key created with idempotencyKeys.create() unchanged while the catalog knows it", async () => {
+    const created = await createIdempotencyKey("my-key", { scope: "global" });
+    existingKeys = new Set([created]);
+
+    expect(await resetAndCaptureKey("my-task", created)).toBe(created);
+    expect(await resetAndCaptureKey("my-task", created, { scope: "global" })).toBe(created);
+  });
+
+  it("sends a created key unchanged when no scope is passed and the catalog is cold", async () => {
+    const created = await createIdempotencyKey("my-key", { scope: "global" });
+
+    // The reset can happen in a different process from the create
+    resetIdempotencyKeyCatalog();
+    existingKeys = new Set([created]);
+
+    expect(await resetAndCaptureKey("my-task", created)).toBe(created);
+  });
+
+  it("falls back to the verbatim key when a created key is reset with a scope and the catalog is cold", async () => {
+    const created = await createIdempotencyKey("my-key", { scope: "global" });
+
+    resetIdempotencyKeyCatalog();
+    existingKeys = new Set([created]);
+
+    await resetIdempotencyKey("my-task", created, { scope: "global" });
+
+    // The derived hash misses, so the already-hashed key is retried verbatim
+    expect(resetKeys).toEqual([await digestSHA256(created), created]);
+  });
+
+  it("sends a 64-character key unchanged when no scope is passed", async () => {
+    expect(await resetAndCaptureKey("my-task", digestShapedKey)).toBe(digestShapedKey);
+  });
+
+  it("resets 64-character material that trigger stored verbatim when no scope is passed", async () => {
+    // trigger() forwards 64-character material as-is, so that is what the server stored
+    expect(await makeIdempotencyKey(digestShapedKey)).toBe(digestShapedKey);
+    existingKeys = new Set([digestShapedKey]);
+
+    expect(await resetAndCaptureKey("my-task", digestShapedKey)).toBe(digestShapedKey);
+  });
+
+  it("does not fall back when the derived hash for 64-character material matches", async () => {
+    const created = await createIdempotencyKey(digestShapedKey, { scope: "global" });
+
+    resetIdempotencyKeyCatalog();
+    existingKeys = new Set([created]);
+
+    await resetIdempotencyKey("my-task", digestShapedKey, { scope: "global" });
+
+    expect(resetKeys).toEqual([created]);
+  });
+
+  it("falls back to the verbatim key when the derived hash fails with a 503", async () => {
+    // The server answers 503, not 404, when it cannot check the buffer for a miss
+    const created = await createIdempotencyKey("my-key", { scope: "global" });
+
+    resetIdempotencyKeyCatalog();
+    statusByKey.set(await digestSHA256(created), 503);
+    existingKeys = new Set([created]);
+
+    await resetIdempotencyKey(
+      "my-task",
+      created,
+      { scope: "global" },
+      { retry: { maxAttempts: 1 } }
+    );
+
+    expect(resetKeys).toEqual([await digestSHA256(created), created]);
+  });
+
+  it("surfaces the derived key's error when it fails with a 503 and the fallback finds nothing", async () => {
+    const derived = await digestSHA256(digestShapedKey);
+    statusByKey.set(derived, 503);
+    existingKeys = new Set();
+
+    await expect(
+      resetIdempotencyKey(
+        "my-task",
+        digestShapedKey,
+        { scope: "global" },
+        { retry: { maxAttempts: 1 } }
+      )
+    ).rejects.toMatchObject({ status: 503 });
+
+    expect(resetKeys).toEqual([derived, digestShapedKey]);
+  });
+
+  it("surfaces the fallback's error when it fails with something other than a 404", async () => {
+    const derived = await digestSHA256(digestShapedKey);
+    statusByKey.set(derived, 404);
+    statusByKey.set(digestShapedKey, 503);
+
+    await expect(
+      resetIdempotencyKey(
+        "my-task",
+        digestShapedKey,
+        { scope: "global" },
+        { retry: { maxAttempts: 1 } }
+      )
+    ).rejects.toMatchObject({ status: 503 });
+
+    expect(resetKeys).toEqual([derived, digestShapedKey]);
+  });
+
+  it("surfaces the derived key's error when both attempts 404", async () => {
+    const derived = await digestSHA256(digestShapedKey);
+    existingKeys = new Set();
+
+    await expect(
+      resetIdempotencyKey("my-task", digestShapedKey, { scope: "global" })
+    ).rejects.toThrow(notFoundMessage(derived));
+
+    expect(resetKeys).toEqual([derived, digestShapedKey]);
+  });
+
+  it("hashes key material that is not 64 characters", async () => {
+    const created = await createIdempotencyKey("my-key", { scope: "global" });
+    resetIdempotencyKeyCatalog();
+
+    expect(await resetAndCaptureKey("my-task", "my-key", { scope: "global" })).toBe(created);
+  });
+
+  it("sends a 64-character key verbatim when run scope cannot be derived", async () => {
+    const created = await createIdempotencyKey("my-key", { scope: "run" });
+
+    resetIdempotencyKeyCatalog();
+    existingKeys = new Set([created]);
+
+    // No parentRunId and no task context, so the hash is underivable
+    expect(await resetAndCaptureKey("my-task", created, { scope: "run" })).toBe(created);
+  });
+
+  it("sends a 64-character key verbatim when attempt scope cannot be derived", async () => {
+    existingKeys = new Set([digestShapedKey]);
+
+    expect(await resetAndCaptureKey("my-task", digestShapedKey, { scope: "attempt" })).toBe(
+      digestShapedKey
+    );
+  });
+
+  it("still throws for non-64-character material when run scope cannot be derived", async () => {
+    await expect(resetIdempotencyKey("my-task", "my-key", { scope: "run" })).rejects.toThrow(
+      "parentRunId is required for 'run' scope"
+    );
+
+    expect(resetKeys).toEqual([]);
+  });
+
+  it("still throws for non-64-character material when attempt scope cannot be derived", async () => {
+    await expect(
+      resetIdempotencyKey("my-task", "my-key", { scope: "attempt", parentRunId: "run_abc123" })
+    ).rejects.toThrow("parentRunId and attemptNumber are required for 'attempt' scope");
+
+    expect(resetKeys).toEqual([]);
+  });
+});
diff --git a/packages/core/src/v3/idempotencyKeys.ts b/packages/core/src/v3/idempotencyKeys.ts
index 585f38c1c3..643a22ae98 100644
--- a/packages/core/src/v3/idempotencyKeys.ts
+++ b/packages/core/src/v3/idempotencyKeys.ts
@@ -8,6 +8,7 @@ import { taskContext } from "./task-context-api.js";
 import type { IdempotencyKey } from "./types/idempotencyKeys.js";
 import { digestSHA256 } from "./utils/crypto.js";
 import type { ZodFetchOptions } from "./apiClient/core.js";
+import { NotFoundError } from "./apiClient/errors.js";
 
 // Re-export types from catalog for backwards compatibility
 export type {
@@ -234,19 +235,19 @@ export async function resetIdempotencyKey(
 ): Promise<{ id: string }> {
   const client = apiClientManager.clientOrThrow();
 
-  // If the key is already a 64-char hash, use it directly
-  if (typeof idempotencyKey === "string" && idempotencyKey.length === 64) {
-    return client.resetIdempotencyKey(taskIdentifier, idempotencyKey, requestOptions);
-  }
+  // A 64-char key is only assumed pre-hashed if the catalog knows it, or there's no scope to hash with
+  const is64CharKey = typeof idempotencyKey === "string" && idempotencyKey.length === 64;
 
-  // Try to extract options from an IdempotencyKey created with idempotencyKeys.create()
-  const attachedOptions =
-    typeof idempotencyKey === "string" ? getIdempotencyKeyOptions(idempotencyKey) : undefined;
+  if (is64CharKey) {
+    const isCreatedKey = getIdempotencyKeyOptions(idempotencyKey) !== undefined;
 
-  const scope = attachedOptions?.scope ?? options?.scope ?? "run";
-  const keyArray = Array.isArray(idempotencyKey)
-    ? idempotencyKey
-    : [attachedOptions?.key ?? String(idempotencyKey)];
+    if (isCreatedKey || options?.scope === undefined) {
+      return client.resetIdempotencyKey(taskIdentifier, idempotencyKey, requestOptions);
+    }
+  }
+
+  const scope = options?.scope ?? "run";
+  const keyArray = Array.isArray(idempotencyKey) ? idempotencyKey : [idempotencyKey];
 
   // Build scope suffix based on scope type
   let scopeSuffix: string[] = [];
@@ -254,6 +255,10 @@ export async function resetIdempotencyKey(
     case "run": {
       const parentRunId = options?.parentRunId ?? taskContext?.ctx?.run.id;
       if (!parentRunId) {
+        // We can't derive a hash, but a 64-char key may already be one, so try it rather than fail
+        if (is64CharKey) {
+          return client.resetIdempotencyKey(taskIdentifier, idempotencyKey, requestOptions);
+        }
         throw new Error(
           "resetIdempotencyKey: parentRunId is required for 'run' scope when called outside a task context"
         );
@@ -265,6 +270,9 @@ export async function resetIdempotencyKey(
       const parentRunId = options?.parentRunId ?? taskContext?.ctx?.run.id;
       const attemptNumber = options?.attemptNumber ?? taskContext?.ctx?.attempt.number;
       if (!parentRunId || attemptNumber === undefined) {
+        if (is64CharKey) {
+          return client.resetIdempotencyKey(taskIdentifier, idempotencyKey, requestOptions);
+        }
         throw new Error(
           "resetIdempotencyKey: parentRunId and attemptNumber are required for 'attempt' scope when called outside a task context"
         );
@@ -277,5 +285,18 @@ export async function resetIdempotencyKey(
   // Generate the hash using the same algorithm as createIdempotencyKey
   const hash = await generateIdempotencyKey(keyArray.concat(scopeSuffix));
 
-  return client.resetIdempotencyKey(taskIdentifier, hash, requestOptions);
+  if (!is64CharKey) {
+    return client.resetIdempotencyKey(taskIdentifier, hash, requestOptions);
+  }
+
+  // Hashing a 64-char key is a guess, so if it fails at all, still try the key verbatim
+  try {
+    return await client.resetIdempotencyKey(taskIdentifier, hash, requestOptions);
+  } catch (error) {
+    try {
+      return await client.resetIdempotencyKey(taskIdentifier, idempotencyKey, requestOptions);
+    } catch (fallbackError) {
+      throw fallbackError instanceof NotFoundError ? error : fallbackError;
+    }
+  }
 }