diff --git a/README.md b/README.md
index f083fb49d..788b8d2ab 100644
--- a/README.md
+++ b/README.md
@@ -75,6 +75,8 @@ export class App {
 
 [Upgrading from AngularFire 20? See the v21 upgrade guide.](docs/version-21-upgrade.md)
 
+[Upgrading from AngularFire 21? See the v22 upgrade guide.](docs/version-22-upgrade.md)
+
 ### Sample app
 
 The [`sample`](sample) folder contains a kitchen sink application that demonstrates use of the "modular" API, in a zoneless server-rendered application, with all the bells and whistles.
diff --git a/docs/version-22-upgrade.md b/docs/version-22-upgrade.md
new file mode 100644
index 000000000..159a1673c
--- /dev/null
+++ b/docs/version-22-upgrade.md
@@ -0,0 +1,58 @@
+# Upgrading to the AngularFire 22 canary
+
+AngularFire 22 targets **Angular 22** and the **Firebase JS SDK v12**. Most of the upgrade is handled for you by `ng update`.
+
+## Run the update
+
+AngularFire 22 is published under the `canary` tag, a build of every merge to `main`, until a release candidate is published under `next`. From an app on Angular 21 and AngularFire 21, run:
+
+```bash
+ng update @angular/core@22 @angular/cli@22 @angular/fire@canary
+```
+
+Include `@angular/fire@canary` in the same command as Angular. On its own, `ng update @angular/core@22 @angular/cli@22` refuses to run while AngularFire 21 is installed, because AngularFire 21 only accepts Angular 21.
+
+The AngularFire update runs a migration that:
+
+- **Adds** `firebase` **to your** `package.json` **if it is missing**, as `"firebase": "^12.18.0"`, and reinstalls. See the next section for why.
+- **Aligns an existing** `firebase` **entry to** `^12.18.0` when it requests a version outside that range.
+
+## Your app now owns the Firebase SDK
+
+Through AngularFire 21, `@angular/fire` listed `firebase` under `dependencies`, so npm could install a second copy of the SDK under `node_modules/` whenever your app asked for a different version. The two copies reject each other's objects at runtime, with errors such as `Expected type '_Query', but it was: a custom _CollectionReference object` or `toDate is not a function`.
+
+AngularFire 22 lists `firebase` under `peerDependencies` instead. So your app should declare `firebase` in its `package.json` (on Yarn it must, since Yarn installs no peer dependencies). This gives you exactly one copy of `firebase`, and an incompatible version is refused at install time instead of failing at runtime.
+
+`ng update @angular/fire@canary` updates an older `firebase` entry in your `package.json` to `^12.18.0` when it requests a version outside that range. If your app doesn't list `firebase` in `package.json` the migration adds `"firebase": "^12.18.0"` and reinstalls. Verify with `npm ls firebase`, which should show exactly one copy.
+
+### If you install with `npm install` instead of `ng update`
+
+Add the dependency yourself:
+
+```bash
+npm install @angular/fire@canary firebase@^12.18.0
+```
+
+npm 7 and later install a missing peer dependency automatically, so `npm install @angular/fire@canary` alone also works, but it does not write `firebase` into your `package.json`. Declare it so that a later install cannot change which version you get.
+
+### If npm stops with `ERESOLVE`
+
+An app that requests a `firebase` version outside the range AngularFire 22 supports now fails to install with an `ERESOLVE` error. Update your `firebase` entry to a version inside the range given in the error message, then install again:
+
+```bash
+npm install firebase@^12.18.0
+```
+
+Do not use `--force` or `--legacy-peer-deps` to get past this message. Both install the older SDK next to AngularFire 22 and the runtime errors described above come back. If your project has `legacy-peer-deps=true` in its `.npmrc`, remove it before upgrading.
+
+### Yarn
+
+Yarn doesn't install peer dependencies. Add `firebase` to your own `package.json` as shown above, or run `ng update @angular/fire@canary`, which adds it.
+
+An older version installs anyway with a warning (`has incorrect peer dependency "firebase@^12.18.0"` on Yarn 1, `YN0060: INCOMPATIBLE_PEER_DEPENDENCY` on Yarn 2+), so treat that warning as an upgrade step you still have to do.
+
+### pnpm
+
+pnpm 8 and later install a missing `firebase` automatically. An older version installs anyway with a warning (`unmet peer firebase@^12.18.0: found 11.x` on pnpm 9 and 10, `Issues with peer dependencies found. Run "pnpm peers check" to list them.` on pnpm 11 and 12), and pnpm prints that warning only once, when it first resolves the tree, never on a later install from the committed lockfile.
+
+Set `strict-peer-dependencies=true` in `.npmrc` to make pnpm refuse the mismatch outright.
diff --git a/src/ng-package.json b/src/ng-package.json
index 0eb72fb12..9e2805084 100644
--- a/src/ng-package.json
+++ b/src/ng-package.json
@@ -7,6 +7,6 @@
   "allowedNonPeerDependencies": [
     "@angular-devkit/architect", "@angular-devkit/core",
     "@angular-devkit/schematics", "@schematics/angular",
-    "jsonc-parser", "firebase", "rxfire"
+    "jsonc-parser", "rxfire"
   ]
 }
diff --git a/src/package.json b/src/package.json
index 9f2537957..4f141d993 100644
--- a/src/package.json
+++ b/src/package.json
@@ -31,6 +31,7 @@
     "@angular/common": "^22.0.0",
     "@angular/core": "^22.0.0",
     "@angular/platform-browser": "^22.0.0",
+    "firebase": "^12.18.0",
     "rxjs": "~7.8.0",
     "firebase-tools": "^14.0.0 || ^15.0.0",
     "typescript": ">=6.0 <6.1"
@@ -40,7 +41,6 @@
     "typescript": { "optional": true }
   },
   "dependencies": {
-    "firebase": "^12.18.0",
     "rxfire": "^6.2.0",
     "@angular-devkit/architect": ">= 0.2200.0 < 0.2300.0",
     "@angular-devkit/core": "^22.0.0",
diff --git a/src/schematics/common.jasmine.ts b/src/schematics/common.jasmine.ts
index c9209cb71..2a55eaa64 100644
--- a/src/schematics/common.jasmine.ts
+++ b/src/schematics/common.jasmine.ts
@@ -214,9 +214,9 @@ describe('alignFirebaseVersion', () => {
     expect(sectionIn(tree, 'devDependencies').firebase).toBe(firebaseVersionRange);
   });
 
-  it('matches the firebase range the library actually ships with', () => {
+  it('matches the firebase range the library declares as its peer dependency', () => {
     const libraryManifest = JSON.parse(readFileSync('src/package.json', 'utf8'));
-    expect(libraryManifest.dependencies.firebase).toBe(firebaseVersionRange);
+    expect(libraryManifest.peerDependencies.firebase).toBe(firebaseVersionRange);
   });
 
   it('is a no-op when run a second time', () => {
diff --git a/src/schematics/common.ts b/src/schematics/common.ts
index 4630bcfe9..6df7c8bb1 100644
--- a/src/schematics/common.ts
+++ b/src/schematics/common.ts
@@ -72,22 +72,20 @@ export const addDependencies = (
   overwriteIfExists(host, 'package.json', stringifyFormatted(packageJson));
 };
 
-/* Must stay identical to `dependencies.firebase` in `src/package.json`: if the two drift, the
- * alignment below can pin workspaces outside the range the library actually installs against,
- * re-creating duplicate-SDK trees. */
+/* Must stay identical to `peerDependencies.firebase` in `src/package.json`: if the two drift, the
+ * alignment below writes a range the peer dependency then rejects. */
 export const firebaseVersionRange = '^12.18.0';
 
 /**
  * Aligns the workspace's `firebase` entry with the range `@angular/fire` requires.
  *
- * `@angular/fire` bundles its own `firebase` dependency, so a workspace pinned to an older
- * major never conflicts at install time; npm silently nests a second SDK copy under
- * `@angular/fire`, and the two copies reject each other's objects at runtime (#3684, #3681,
- * #3682). Rewriting the workspace's range before the install runs is the only point where
- * that class of breakage can be headed off.
+ * `firebase` is a peer dependency of `@angular/fire`. Depending on the package manager and its
+ * settings, a workspace range outside it is refused at install time or installs a `firebase`
+ * the library was not built against, and a workspace that never declared `firebase` gets no
+ * entry written. Rewriting the entry before the install runs heads both off.
  *
  * Returns whether `package.json` was modified, so callers can skip scheduling an install
- * when nothing changed (`ng update` re-runs the v21 migration on rc-to-stable updates).
+ * when nothing changed (`ng update` re-runs a migration on rc-to-stable updates).
  */
 export const alignFirebaseVersion = (
   host: Tree,
@@ -119,8 +117,8 @@ export const alignFirebaseVersion = (
     } catch (_) {
       context.logger.warn(
         `⚠️ The firebase version in your package.json (${declaredFirebaseVersion}) is not a semver ` +
-        `range, so it was left as-is; make sure it resolves inside ${firebaseVersionRange}, the ` +
-        'range @angular/fire requires; a version outside it can leave the install with two copies of the firebase SDK.'
+        `range, so it was left as-is. Make sure it resolves inside ${firebaseVersionRange}, the ` +
+        'range @angular/fire requires. A version outside it either fails to install or installs a firebase that @angular/fire was not built against.'
       );
       continue;
     }
@@ -128,8 +126,8 @@ export const alignFirebaseVersion = (
     packageJson[section].firebase = firebaseVersionRange;
     context.logger.info(
       `Updated the firebase version in your package.json from ${declaredFirebaseVersion} to ` +
-      `${firebaseVersionRange}, the range @angular/fire requires; a workspace range outside it ` +
-      'can leave the install with a second copy of the firebase SDK, which fails at runtime.'
+      `${firebaseVersionRange}, the range @angular/fire requires. A range outside it either fails ` +
+      'to install or installs a firebase that @angular/fire was not built against.'
     );
     changed = true;
   }
diff --git a/src/schematics/migration.json b/src/schematics/migration.json
index 2a2b926b0..4b99835c5 100644
--- a/src/schematics/migration.json
+++ b/src/schematics/migration.json
@@ -8,8 +8,13 @@
         },
         "migration-v21": {
             "version": "21.0.0",
-            "description": "Align the workspace's firebase dependency with the range @angular/fire 21 requires, and rewrite Vertex AI imports to Firebase AI Logic (getVertexAI callers keep the same backend, and a call that passed no location moves from us-central1 to global)",
+            "description": "Align the workspace's firebase dependency with the range @angular/fire requires, and rewrite Vertex AI imports to Firebase AI Logic (getVertexAI callers keep the same backend, and a call that passed no location moves from us-central1 to global)",
             "factory": "./update/v21#ngUpdate"
+        },
+        "migration-v22": {
+            "version": "22.0.0",
+            "description": "Add firebase to the workspace's package.json when it is missing, now that @angular/fire lists it as a peer dependency, and align an existing entry with the range @angular/fire requires",
+            "factory": "./update/v22#ngUpdate"
         }
     }
 }
\ No newline at end of file
diff --git a/src/schematics/tsconfig.json b/src/schematics/tsconfig.json
index 5c2536e7d..ca9d80392 100644
--- a/src/schematics/tsconfig.json
+++ b/src/schematics/tsconfig.json
@@ -29,5 +29,6 @@
         "setup/index.ts",
         "update/v7/index.ts",
         "update/v21/index.ts",
+        "update/v22/index.ts",
     ]
 }
\ No newline at end of file
diff --git a/src/schematics/update/v22/index.jasmine.ts b/src/schematics/update/v22/index.jasmine.ts
new file mode 100644
index 000000000..60a171eab
--- /dev/null
+++ b/src/schematics/update/v22/index.jasmine.ts
@@ -0,0 +1,59 @@
+import { logging } from '@angular-devkit/core';
+import { HostTree, SchematicContext } from '@angular-devkit/schematics';
+import { firebaseVersionRange } from '../../common.js';
+import { ngUpdate } from './index.js';
+import 'jasmine';
+
+const contextWithTaskSpy = () => {
+  const addTask = jasmine.createSpy('addTask');
+  const context = {
+    logger: new logging.Logger('test'),
+    addTask,
+  } as unknown as SchematicContext;
+  return { context, addTask };
+};
+
+const treeWithDependencies = (dependencies: Record<string, string>) => {
+  const tree = new HostTree();
+  tree.create('package.json', JSON.stringify({ name: 'test-app', dependencies }, null, 2));
+  return tree;
+};
+
+const dependenciesIn = (tree: HostTree) => JSON.parse(tree.readText('package.json')).dependencies;
+
+describe('migration-v22 ngUpdate', () => {
+
+  it('adds firebase when the workspace never declared it and schedules an install', () => {
+    const { context, addTask } = contextWithTaskSpy();
+    const tree = treeWithDependencies({ '@angular/fire': '^22.0.0' });
+    ngUpdate()(tree, context);
+    expect(dependenciesIn(tree).firebase).toBe(firebaseVersionRange);
+    expect(addTask).toHaveBeenCalledTimes(1);
+  });
+
+  it('aligns a firebase range outside the peer range and schedules an install', () => {
+    const { context, addTask } = contextWithTaskSpy();
+    const tree = treeWithDependencies({ firebase: '^11.0.0' });
+    ngUpdate()(tree, context);
+    expect(dependenciesIn(tree).firebase).toBe(firebaseVersionRange);
+    expect(addTask).toHaveBeenCalledTimes(1);
+  });
+
+  it('schedules nothing when the workspace is already aligned', () => {
+    const { context, addTask } = contextWithTaskSpy();
+    const tree = treeWithDependencies({ firebase: firebaseVersionRange });
+    ngUpdate()(tree, context);
+    expect(dependenciesIn(tree).firebase).toBe(firebaseVersionRange);
+    expect(addTask).not.toHaveBeenCalled();
+  });
+
+  it('is a no-op on the second run', () => {
+    const { context, addTask } = contextWithTaskSpy();
+    const tree = treeWithDependencies({});
+    ngUpdate()(tree, context);
+    ngUpdate()(tree, context);
+    expect(dependenciesIn(tree).firebase).toBe(firebaseVersionRange);
+    expect(addTask).toHaveBeenCalledTimes(1);
+  });
+
+});
diff --git a/src/schematics/update/v22/index.ts b/src/schematics/update/v22/index.ts
new file mode 100644
index 000000000..0b0dd4b3a
--- /dev/null
+++ b/src/schematics/update/v22/index.ts
@@ -0,0 +1,14 @@
+import { Rule, SchematicContext, Tree } from '@angular-devkit/schematics';
+import { NodePackageInstallTask } from '@angular-devkit/schematics/tasks/index.js';
+import { alignFirebaseVersion } from '../../common.js';
+
+/* `ng update` runs this migration again on every prerelease step of the same release (rc.0 to
+ * rc.1, rc.1 to 22.0.0), so it must change nothing when the workspace is already aligned. */
+export const ngUpdate = (): Rule => (host: Tree, context: SchematicContext) => {
+  /* `ng update` updates a `firebase` entry the workspace already has, but adds none to a workspace
+   * that has no `firebase` entry at all. Under a peer dependency that workspace needs one. */
+  if (alignFirebaseVersion(host, context)) {
+    context.addTask(new NodePackageInstallTask());
+  }
+  return host;
+};
diff --git a/tools/build.ts b/tools/build.ts
index c512f867e..01ceeea36 100644
--- a/tools/build.ts
+++ b/tools/build.ts
@@ -383,6 +383,7 @@ const schematicEntryPoints = [
   ['setup', 'index'],
   ['update', 'v7', 'index'],
   ['update', 'v21', 'index'],
+  ['update', 'v22', 'index'],
 ];
 
 const externalPackages = [