Add rev and cache parameters to @client decorator

rev=N: bumped by developer when function logic changes. Becomes part of
the HMAC cache key — old cache entries are unreachable without purge.
Effective rev for a context is max(rev) across all functions in it.

cache=int|False|True: TTL escape hatch for unobservable mutations.
cache=60 emits s-maxage=60. cache=False emits no-store. Default (True)
emits s-maxage=31536000 (forever, purge on mutation).
Effective cache for a context is min(TTL) across functions, with False
taking precedence.

Both parameters flow through: decorator → meta → manifest → cache key
and Cache-Control headers. Implemented in both Python and TypeScript
with 13 Python tests and 4 TypeScript tests.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/mizan-django/src/mizan/client/executor.py

@@ -775,22 +775,51 @@ def context_fetch_view(request: HttpRequest, context_name: str) -> JsonResponse:
 
     params = request.GET.dict()
 
-    # Origin-side cache lookup
+    # Resolve effective rev and cache policy across all functions in this context
     _cache_log = logging.getLogger("mizan.cache")
-    cache = get_cache()
+    groups = get_context_groups()
+    fn_names = groups.get(context_name, [])
+    effective_rev = 0
+    effective_cache: int | bool = True  # True=forever, False=no-store, int=TTL
+    for fn_name in fn_names:
+        fn_cls = get_function(fn_name)
+        if fn_cls:
+            meta = getattr(fn_cls, "_meta", {})
+            fn_rev = meta.get("rev", 0)
+            effective_rev = max(effective_rev, fn_rev)
+            fn_cache = meta.get("cache", True)
+            if fn_cache is False:
+                effective_cache = False
+                break
+            elif isinstance(fn_cache, int):
+                if effective_cache is True:
+                    effective_cache = fn_cache
+                else:
+                    effective_cache = min(effective_cache, fn_cache)
+
+    # Origin-side cache lookup (skip if cache=False)
+    cache_backend = get_cache()
     cache_settings = get_settings()
     user_id = None
     if hasattr(request, "user") and hasattr(request.user, "pk") and request.user.pk:
         user_id = str(request.user.pk)
-    if cache is not None and cache_settings.cache_secret:
+    use_cache = (
+        cache_backend is not None
+        and cache_settings.cache_secret
+        and effective_cache is not False
+    )
+    if use_cache:
         try:
             cached = cache_get(
-                cache_settings.cache_secret, cache, context_name, params,
-                user_id=user_id,
+                cache_settings.cache_secret, cache_backend, context_name, params,
+                user_id=user_id, rev=effective_rev,
             )
             if cached is not None:
                 response = HttpResponse(cached, content_type="application/json")
-                response["Cache-Control"] = "public, max-age=0, s-maxage=31536000"
+                if isinstance(effective_cache, int):
+                    response["Cache-Control"] = f"public, max-age=0, s-maxage={effective_cache}"
+                else:
+                    response["Cache-Control"] = "public, max-age=0, s-maxage=31536000"
                 response["X-Mizan-Cache"] = "HIT"
                 return response
         except Exception:
@@ -815,19 +844,20 @@ def context_fetch_view(request: HttpRequest, context_name: str) -> JsonResponse:
     # Deterministic JSON (sorted keys) for consistent cache keys
     response = JsonResponse(result.data, json_dumps_params={"sort_keys": True})
 
-    # CDN-ready headers
-    # max-age=0: browser always revalidates (gets 304 from CDN if unchanged)
-    # s-maxage=31536000: CDN caches forever; purge is the freshness mechanism
-    # No Vary header — Cloudflare ignores Vary for personalized content.
-    # User-scoped cache keying will use HMAC-based keys instead.
-    response["Cache-Control"] = "public, max-age=0, s-maxage=31536000"
+    # CDN-ready headers based on effective cache policy
+    if effective_cache is False:
+        response["Cache-Control"] = "no-store"
+    elif isinstance(effective_cache, int):
+        response["Cache-Control"] = f"public, max-age=0, s-maxage={effective_cache}"
+    else:
+        response["Cache-Control"] = "public, max-age=0, s-maxage=31536000"
 
-    # Store in origin-side cache
-    if cache is not None and cache_settings.cache_secret:
+    # Store in origin-side cache (skip if cache=False)
+    if use_cache:
         try:
             cache_put(
-                cache_settings.cache_secret, cache, context_name, params,
-                response.content, user_id=user_id,
+                cache_settings.cache_secret, cache_backend, context_name, params,
+                response.content, user_id=user_id, rev=effective_rev,
             )
             response["X-Mizan-Cache"] = "MISS"
         except Exception:

packages/mizan-django/src/mizan/client/function.py

@@ -261,6 +261,8 @@ def client(
     methods: list[str] | None = None,
     websocket: bool = False,
     auth: bool | str | Callable[[Any], bool] | None = None,
+    rev: int = 0,
+    cache: int | bool = True,
 ) -> type[ServerFunction] | Callable[[Callable], type[ServerFunction]]:
     """
     Register a function as a server function.
@@ -336,7 +338,7 @@ def client(
         return _create_server_function(
             fn, context=resolved_context, affects=affects,
             private=private, route=route, methods=methods,
-            websocket=websocket, auth=auth,
+            websocket=websocket, auth=auth, rev=rev, cache=cache,
         )
 
     # Support both @client and @client(...)
@@ -344,7 +346,7 @@ def client(
         return _create_server_function(
             fn, context=resolved_context, affects=affects,
             private=private, route=route, methods=methods,
-            websocket=websocket, auth=auth,
+            websocket=websocket, auth=auth, rev=rev, cache=cache,
         )
     return decorator
 
@@ -387,6 +389,8 @@ def _create_server_function(
     methods: list[str] | None = None,
     websocket: bool = False,
     auth: bool | str | None = None,
+    rev: int = 0,
+    cache: int | bool = True,
 ) -> type[ServerFunction]:
     """Internal helper that creates a ServerFunction from a decorated function."""
     from pydantic import create_model
@@ -523,6 +527,15 @@ def _create_server_function(
         else:
             meta["auth"] = auth
 
+    # Revision: bumped by developer when function logic changes.
+    # Part of the HMAC cache key — old entries become unreachable orphans.
+    if rev != 0:
+        meta["rev"] = rev
+
+    # Cache policy: True=forever (default), False=no-store, int=TTL seconds
+    if cache is not True:
+        meta["cache"] = cache
+
     if meta:
         FunctionWrapper._meta = {**FunctionWrapper._meta, **meta}
 

packages/mizan-django/src/mizan/export/__init__.py

@@ -428,6 +428,12 @@ def generate_edge_manifest(
                 fn_entry["methods"] = meta.get("methods", ["GET"])
                 page_routes.append(fn_route)
 
+            # Cache protocol metadata
+            if "rev" in meta:
+                fn_entry["rev"] = meta["rev"]
+            if "cache" in meta:
+                fn_entry["cache"] = meta["cache"]
+
             functions_meta.append(fn_entry)
 
         sorted_params = sorted(param_names)

packages/mizan-django/src/mizan/tests/test_core.py

@@ -3028,3 +3028,227 @@ class CacheIntegrationTests(TestCase):
         # User 6 should still be cached
         r6 = self._fetch_context("user_id=6")
         self.assertEqual(r6.get("X-Mizan-Cache"), "HIT")
+
+
+# ── Rev and cache parameter tests ──────────────────────────────────────────
+
+
+class RevParameterTests(TestCase):
+    """Tests for the @client(rev=N) parameter."""
+
+    def setUp(self):
+        clear_registry()
+
+    def tearDown(self):
+        clear_registry()
+
+    def test_rev_stored_in_meta(self):
+        """@client(rev=2) stores rev in function metadata."""
+        Ctx = ReactContext("data")
+
+        @client(context=Ctx, rev=2)
+        def my_fn(request: HttpRequest) -> dict:
+            return {}
+
+        register(my_fn, "my_fn")
+        meta = getattr(get_function("my_fn"), "_meta", {})
+        self.assertEqual(meta["rev"], 2)
+
+    def test_rev_default_not_in_meta(self):
+        """@client with default rev=0 does not store rev in meta."""
+        Ctx = ReactContext("data")
+
+        @client(context=Ctx)
+        def my_fn(request: HttpRequest) -> dict:
+            return {}
+
+        register(my_fn, "my_fn")
+        meta = getattr(get_function("my_fn"), "_meta", {})
+        self.assertNotIn("rev", meta)
+
+    def test_rev_changes_cache_key(self):
+        """Different rev values produce different HMAC cache keys."""
+        from mizan.cache.keys import derive_cache_key
+
+        key_v0 = derive_cache_key("secret", "ctx", {"id": "1"}, rev=0)
+        key_v1 = derive_cache_key("secret", "ctx", {"id": "1"}, rev=1)
+        self.assertNotEqual(key_v0, key_v1)
+
+    def test_rev_in_manifest(self):
+        """Manifest includes rev on functions that set it."""
+        from mizan.export import generate_edge_manifest
+
+        Ctx = ReactContext("data")
+
+        @client(context=Ctx, rev=3)
+        def versioned_fn(request: HttpRequest, item_id: int) -> dict:
+            return {}
+
+        register(versioned_fn, "versioned_fn")
+        manifest = generate_edge_manifest()
+        fn_entry = manifest["contexts"]["data"]["functions"][0]
+        self.assertEqual(fn_entry["rev"], 3)
+
+    def test_rev_not_in_manifest_when_default(self):
+        """Manifest omits rev when it's the default (0)."""
+        from mizan.export import generate_edge_manifest
+
+        Ctx = ReactContext("data")
+
+        @client(context=Ctx)
+        def default_fn(request: HttpRequest) -> dict:
+            return {}
+
+        register(default_fn, "default_fn")
+        manifest = generate_edge_manifest()
+        fn_entry = manifest["contexts"]["data"]["functions"][0]
+        self.assertNotIn("rev", fn_entry)
+
+
+class CacheParameterTests(TestCase):
+    """Tests for the @client(cache=...) parameter."""
+
+    def setUp(self):
+        clear_registry()
+
+    def tearDown(self):
+        clear_registry()
+
+    def test_cache_int_stored_in_meta(self):
+        """@client(cache=60) stores cache TTL in meta."""
+        Ctx = ReactContext("data")
+
+        @client(context=Ctx, cache=60)
+        def my_fn(request: HttpRequest) -> dict:
+            return {}
+
+        register(my_fn, "my_fn")
+        meta = getattr(get_function("my_fn"), "_meta", {})
+        self.assertEqual(meta["cache"], 60)
+
+    def test_cache_false_stored_in_meta(self):
+        """@client(cache=False) stores False in meta."""
+        Ctx = ReactContext("data")
+
+        @client(context=Ctx, cache=False)
+        def my_fn(request: HttpRequest) -> dict:
+            return {}
+
+        register(my_fn, "my_fn")
+        meta = getattr(get_function("my_fn"), "_meta", {})
+        self.assertIs(meta["cache"], False)
+
+    def test_cache_default_not_in_meta(self):
+        """Default cache=True is not stored in meta."""
+        Ctx = ReactContext("data")
+
+        @client(context=Ctx)
+        def my_fn(request: HttpRequest) -> dict:
+            return {}
+
+        register(my_fn, "my_fn")
+        meta = getattr(get_function("my_fn"), "_meta", {})
+        self.assertNotIn("cache", meta)
+
+    def test_cache_in_manifest(self):
+        """Manifest includes cache TTL on functions that set it."""
+        from mizan.export import generate_edge_manifest
+
+        Ctx = ReactContext("data")
+
+        @client(context=Ctx, cache=120)
+        def ttl_fn(request: HttpRequest) -> dict:
+            return {}
+
+        register(ttl_fn, "ttl_fn")
+        manifest = generate_edge_manifest()
+        fn_entry = manifest["contexts"]["data"]["functions"][0]
+        self.assertEqual(fn_entry["cache"], 120)
+
+
+class CachePolicyIntegrationTests(TestCase):
+    """Tests for effective cache policy resolution in context_fetch_view."""
+
+    def setUp(self):
+        clear_registry()
+
+    def tearDown(self):
+        clear_registry()
+
+    def test_cache_int_sets_smaxage(self):
+        """Context with cache=60 emits s-maxage=60."""
+        Ctx = ReactContext("trending")
+
+        @client(context=Ctx, cache=60)
+        def trending(request: HttpRequest) -> dict:
+            return {"items": []}
+
+        register(trending, "trending")
+        response = self.client.get("/api/mizan/ctx/trending/")
+        self.assertIn("s-maxage=60", response["Cache-Control"])
+        self.assertNotIn("31536000", response["Cache-Control"])
+
+    def test_cache_false_sets_nostore(self):
+        """Context with cache=False emits no-store."""
+        Ctx = ReactContext("random")
+
+        @client(context=Ctx, cache=False)
+        def random_fn(request: HttpRequest) -> dict:
+            return {"value": 42}
+
+        register(random_fn, "random_fn")
+        response = self.client.get("/api/mizan/ctx/random/")
+        self.assertEqual(response["Cache-Control"], "no-store")
+
+    def test_effective_cache_is_minimum(self):
+        """Context with mixed TTLs uses the minimum."""
+        Ctx = ReactContext("mixed")
+
+        @client(context=Ctx, cache=300)
+        def slow_fn(request: HttpRequest) -> dict:
+            return {"slow": True}
+
+        @client(context=Ctx, cache=60)
+        def fast_fn(request: HttpRequest) -> dict:
+            return {"fast": True}
+
+        register(slow_fn, "slow_fn")
+        register(fast_fn, "fast_fn")
+        response = self.client.get("/api/mizan/ctx/mixed/")
+        self.assertIn("s-maxage=60", response["Cache-Control"])
+
+    def test_effective_rev_is_maximum(self):
+        """Context with mixed revs uses the maximum for cache key."""
+        from mizan.cache.keys import derive_cache_key
+        from mizan.cache import set_cache, reset_cache
+        from mizan.cache.backend import MemoryCache
+        from mizan.setup.settings import clear_settings_cache
+        from django.test import override_settings
+
+        Ctx = ReactContext("versioned")
+
+        @client(context=Ctx, rev=0)
+        def old_fn(request: HttpRequest, item_id: int) -> dict:
+            return {"old": True}
+
+        @client(context=Ctx, rev=2)
+        def new_fn(request: HttpRequest, item_id: int) -> dict:
+            return {"new": True}
+
+        register(old_fn, "old_fn")
+        register(new_fn, "new_fn")
+
+        mem_cache = MemoryCache()
+        set_cache(mem_cache)
+
+        with override_settings(MIZAN_CACHE_SECRET="test", MIZAN_CACHE_REDIS_URL="dummy"):
+            clear_settings_cache()
+            r1 = self.client.get("/api/mizan/ctx/versioned/?item_id=1")
+            self.assertEqual(r1.status_code, 200)
+
+            # The cache key should use rev=2 (max)
+            expected_key = derive_cache_key("test", "versioned", {"item_id": "1"}, rev=2)
+            self.assertIn(expected_key, mem_cache._store)
+
+        reset_cache()
+        clear_settings_cache()

packages/mizan-ts/src/decorator.ts

@@ -102,6 +102,8 @@ export function client(optionsOrFn: ClientOptions | ClientOptions, fn?: Function
             route: options.route,
             methods: options.methods,
             auth: options.auth,
+            rev: options.rev,
+            cache: options.cache,
         }
 
         register(entry)
@@ -132,6 +134,8 @@ export function client(optionsOrFn: ClientOptions | ClientOptions, fn?: Function
             route: options.route,
             methods: options.methods,
             auth: options.auth,
+            rev: options.rev,
+            cache: options.cache,
         }
 
         register(entry)

packages/mizan-ts/src/dispatch.ts

@@ -67,12 +67,34 @@ export async function handleContextFetch(
         }
     }
 
+    // Resolve effective cache policy (minimum TTL across all functions)
+    let effectiveCache: number | boolean = true
+    for (const fnName of fnNames) {
+        const entry = getFunction(fnName)
+        if (!entry) continue
+        if (entry.cache === false) { effectiveCache = false; break }
+        if (typeof entry.cache === 'number') {
+            effectiveCache = effectiveCache === true
+                ? entry.cache
+                : Math.min(effectiveCache as number, entry.cache)
+        }
+    }
+
+    let cacheControl: string
+    if (effectiveCache === false) {
+        cacheControl = 'no-store'
+    } else if (typeof effectiveCache === 'number') {
+        cacheControl = `public, max-age=0, s-maxage=${effectiveCache}`
+    } else {
+        cacheControl = 'public, max-age=0, s-maxage=31536000'
+    }
+
     return {
         status: 200,
         body: results,
         headers: {
             'Content-Type': 'application/json',
-            'Cache-Control': 'public, max-age=0, s-maxage=31536000',
+            'Cache-Control': cacheControl,
         },
     }
 }

packages/mizan-ts/src/manifest.ts

@@ -35,6 +35,8 @@ export function generateManifest(baseUrl = '/api/mizan'): EdgeManifest {
                 fnEntry.methods = entry.methods || ['GET']
                 pageRoutes.push(entry.route)
             }
+            if (entry.rev !== undefined && entry.rev !== 0) fnEntry.rev = entry.rev
+            if (entry.cache !== undefined && entry.cache !== true) fnEntry.cache = entry.cache
             functions.push(fnEntry)
         }
 

packages/mizan-ts/src/types.ts

@@ -17,6 +17,8 @@ export interface ClientOptions {
     route?: string
     methods?: string[]
     auth?: boolean
+    rev?: number
+    cache?: number | false
 }
 
 export interface ParamDef {
@@ -36,6 +38,8 @@ export interface RegistryEntry {
     route?: string
     methods?: string[]
     auth?: boolean
+    rev?: number
+    cache?: number | false
 }
 
 export interface ManifestContext {

packages/mizan-ts/tests/edge-compat.test.ts

@@ -228,4 +228,50 @@ describe('Manifest', () => {
         expect(m.mutations.stripeWebhook.route).toBe('/webhooks/stripe/')
         expect(m.mutations.stripeWebhook.methods).toEqual(['POST'])
     })
+
+    test('rev appears in manifest', () => {
+        clearRegistry()
+        const Ctx = new ReactContext('data')
+        client({ context: Ctx, rev: 3 }, async function versionedFn(itemId: number) {
+            return { value: itemId }
+        })
+
+        const m = generateManifest()
+        const fn = m.contexts.data.functions[0]
+        expect(fn.rev).toBe(3)
+    })
+
+    test('cache TTL appears in manifest', () => {
+        clearRegistry()
+        const Ctx = new ReactContext('trending')
+        client({ context: Ctx, cache: 60 }, async function trendingFn() {
+            return { items: [] }
+        })
+
+        const m = generateManifest()
+        const fn = m.contexts.trending.functions[0]
+        expect(fn.cache).toBe(60)
+    })
+
+    test('cache=60 sets s-maxage=60', async () => {
+        clearRegistry()
+        const Ctx = new ReactContext('live')
+        client({ context: Ctx, cache: 60 }, async function liveFn() {
+            return { score: 42 }
+        })
+
+        const r = await handleContextFetch('live', {})
+        expect(r.headers['Cache-Control']).toBe('public, max-age=0, s-maxage=60')
+    })
+
+    test('cache=false sets no-store', async () => {
+        clearRegistry()
+        const Ctx = new ReactContext('random')
+        client({ context: Ctx, cache: false }, async function randomFn() {
+            return { value: Math.random() }
+        })
+
+        const r = await handleContextFetch('random', {})
+        expect(r.headers['Cache-Control']).toBe('no-store')
+    })
 })