diff --git a/TICKETS.md b/TICKETS.md
index 4726b064..2444a7de 100644
--- a/TICKETS.md
+++ b/TICKETS.md
@@ -172,11 +172,11 @@ External multimodule OSS validation of meta-build axioms (structure over configu
 type-owned plugins, attrs-only call sites, closed matrix). **Not** another in-repo sample.
 
 Open coding: **F-115** (`in_progress`, **`priority: now`**, **cron may continue**). **F-094** Portal remains `blocked` (human).
-4h workers: pick F-115 phase C remainder (**F27 library flavors** / Phase D) while gated; if no ticket has `priority: now` / `cron may continue`, respond `[SILENT]` (audit 2026-07-29 gate — interactive “Go ahead” alone is not enough).
+4h workers: pick F-115 **Phase D** case study (or residual dogfood polish) while gated; if no ticket has `priority: now` / `cron may continue`, respond `[SILENT]` (audit 2026-07-29 gate — interactive “Go ahead” alone is not enough).
 
 | ID | Status | Title | Notes |
 |----|--------|-------|-------|
-| F-115 | in_progress · **priority: now** · **cron may continue** | Dogfood Now in Android under Forma | Primary OSS target [`android/nowinandroid`](https://github.com/android/nowinandroid). Design: [`docs/DOGFOOD-NIA.md`](docs/DOGFOOD-NIA.md). **Phase A+B+C through analytics+notifications done:** Hilt/Room/Firebase/Proto DS + features + WM + flavors + designsystem + core:ui + network + **`core:analytics`** + **`core:notifications`{res,util}** (F31). Findings F16–F31. **Next phase C:** F27 library flavors / Phase D case study. No `androidLibrary`. |
+| F-115 | in_progress · **priority: now** · **cron may continue** | Dogfood Now in Android under Forma | Primary OSS target [`android/nowinandroid`](https://github.com/android/nowinandroid). Design: [`docs/DOGFOOD-NIA.md`](docs/DOGFOOD-NIA.md). **Phase A+B+C done through F27 library flavors:** Hilt/Room/Firebase/Proto DS + features + WM + binary flavors + designsystem + core:ui + network + analytics/notifications + **library `productFlavors` + `.forProductFlavor` deps** (F27). Findings F16–F31 (F27 closed). **Next:** Phase D case study. No `androidLibrary`. |
 
 ## Backlog (lower priority / historical GitHub)
 
diff --git a/docs/CALL-SITE-SURFACE.md b/docs/CALL-SITE-SURFACE.md
index db27e96b..9c010985 100644
--- a/docs/CALL-SITE-SURFACE.md
+++ b/docs/CALL-SITE-SURFACE.md
@@ -149,16 +149,19 @@ default).
 
 **Not in scope:** Play App Signing backend integration, library AAR signing APIs.
 
-## Product flavors (F-115 / NiA F7)
+## Product flavors (F-115 / NiA F7 + F27)
 
 | Concern | Owner | Notes |
 |---------|--------|--------|
-| Flavor dimensions + product flavors | **`androidBinary` call site only** (`productFlavors: List<FormaProductFlavor>`) | Wired to AGP `ApplicationExtension.flavorDimensions` + `productFlavors` |
+| Flavor model | **`FormaProductFlavor`** (one global way) | Same data class for binary + library; libraries ignore APK-only fields (`applicationIdSuffix` / `versionNameSuffix`) |
+| Binary flavor dimensions | **`androidBinary(productFlavors=…)`** | Wired to AGP `ApplicationExtension.flavorDimensions` + `productFlavors` |
+| Library flavor dimensions | **`androidUtil` / `impl` / `androidApp` / `composeWidget` (+ thin Hilt wrappers)** (F27) | Wired via `AndroidLibraryFeatureConfiguration` → `LibraryExtension.applyProductFlavors`; registers `src/<flavor>/kotlin`. Intermediate consumers of flavored libraries must declare the **same** dimension list (AGP variant matching). |
 | Build types | **`BuildConfiguration`** (unchanged) | Flavors are **not** stuffed into build-type map |
-| Library / `impl` / `androidApp` flavor API | **None (v1)** | Unflavored libraries resolve against flavored APKs; multi-module `demoImplementation` is a documented gap |
+| Flavor-scoped external deps | **`NamedDependency.forProductFlavor` / `PlatformDependency.forProductFlavor`** | Maps onto AGP `{flavor}Implementation` via `ConfigurationType.CustomConfiguration`; preserves transitive + feature-flag gates |
 | Raw `android { productFlavors { … } }` | **Rejected as happy path** | Escape hatch only |
+| Free-form config name strings at call sites | **Rejected** | Prefer `.forProductFlavor("prod")` over hand-written `"prodImplementation"` |
 
-**Call-site shape (NiA `demo` / `prod`):**
+**Binary call-site shape (NiA `demo` / `prod`):**
 
 ```kotlin
 import tools.forma.android.utils.FormaProductFlavor
@@ -183,11 +186,40 @@ androidBinary(
 // Tasks: assembleDemoDebug / assembleProdDebug (not bare assembleDebug)
 ```
 
-**Empty list (default)** keeps a single unflavored APK so existing samples stay
+**Library + flavor-scoped deps (NiA analytics / notifications):**
+
+```kotlin
+import tools.forma.android.utils.FormaProductFlavor
+
+val contentTypeFlavors = listOf(
+    FormaProductFlavor(name = "demo", dimension = "contentType"),
+    FormaProductFlavor(name = "prod", dimension = "contentType"),
+)
+
+androidUtil(
+    packageName = "com.example.analytics",
+    productFlavors = contentTypeFlavors,
+    dependencies = transitiveDeps(
+        "androidx.compose.runtime:runtime:…",
+    ) +
+        transitivePlatform("com.google.firebase:firebase-bom:33.16.0")
+            .forProductFlavor("prod") +
+        transitiveDeps("com.google.firebase:firebase-analytics")
+            .forProductFlavor("prod"),
+)
+// Sources: src/main/kotlin + src/demo/kotlin + src/prod/kotlin
+// prodImplementation(firebase-bom platform) + prodImplementation(firebase-analytics)
+```
+
+**Empty list (default)** keeps unflavored targets so existing samples stay
 `assembleDebug`. Optional attrs on [FormaProductFlavor]: `versionNameSuffix`,
 `matchingFallbacks`, `manifestPlaceholders`, `buildConfigFields` (BuildConfig
 fields apply only when project-global `buildFeatures.buildConfig` is already on).
 
+Other library DSLs (`impl`, `uiLibrary`, …) can gain `productFlavors` later by
+forwarding into `AndroidLibraryFeatureConfiguration` — **androidUtil** is the
+dogfood path for F27; do not invent per-module raw AGP blocks.
+
 ## AGP BuildFeatures (F-091 / GH #88)
 
 AGP `BuildFeatures` flags are **project-global by default** (all **off**), with
diff --git a/docs/DOGFOOD-NIA.md b/docs/DOGFOOD-NIA.md
index 1d28f544..4fac2641 100644
--- a/docs/DOGFOOD-NIA.md
+++ b/docs/DOGFOOD-NIA.md
@@ -1,6 +1,6 @@
 # Dogfood: Now in Android → Forma (F-115)
 
-**Status:** `in_progress` — phase C through **analytics + notifications** green (F27 library flavors next)  
+**Status:** `in_progress` — phase C through **library product flavors (F27)** green; **Phase D** case study next  
 **Upstream:** [android/nowinandroid](https://github.com/android/nowinandroid) (Apache-2.0)  
 **Pinned checkout (local):** `/Users/claw/work/nowinandroid` @ `7d45eae` (main tip when cloned 2026-07-29)  
 **Dogfood fork:** `/Users/claw/work/nowinandroid-forma`  
@@ -157,8 +157,8 @@ These are the **value** of dogfooding — expected friction, not blockers to ign
 ### F7 — Product flavors `demo` / `prod`
 
 - Affects source sets and dependency variants (`prodImplementation` FCM on sync).
-- **Resolved (binary v1, 2026-07-31):** `FormaProductFlavor` + `androidBinary(productFlavors=…)` — binary-only; `BuildConfiguration` stays build-types. NiA spike: `demo`/`prod` on `contentType`; `assembleDemoDebug` / `assembleProdDebug`.
-- **Still gap (F27):** library-level productFlavors + `demoImplementation`/`prodImplementation` edges (e.g. sync FCM) — not in v1; unflavored libraries resolve against flavored APK.
+- **Resolved (binary v1, 2026-07-31):** `FormaProductFlavor` + `androidBinary(productFlavors=…)` — binary; `BuildConfiguration` stays build-types. NiA spike: `demo`/`prod` on `contentType`; `assembleDemoDebug` / `assembleProdDebug`.
+- **Resolved (library F27, 2026-08-01):** same `FormaProductFlavor` on `androidUtil` / library feature config + `LibraryExtension.applyProductFlavors` + `src/<flavor>/kotlin`; flavor-scoped deps via `.forProductFlavor("prod")` → `prodImplementation`.
 
 ## Phased execution plan
 
@@ -352,7 +352,7 @@ Workspace: same **`forma-spike`** external tree.
 | Spike binary | `hiltFirebaseBinary(productFlavors = demo+prod contentType)`; demo `applicationIdSuffix = ".demo"` |
 | Tasks | `:binary:assembleDemoDebug` + `:binary:assembleProdDebug` (bare `assembleDebug` gone once flavored) |
 | **F7** | closed for APK root |
-| **F27** | multi-module library flavors / variant deps (e.g. sync FCM) — not in v1; unflavored libraries resolve against flavored APK. |
+| **F27** | closed in library flavors section below |
 | Verify | `forma-spike` assembleDemoDebug + assembleProdDebug green after `publish-local 0.1.3-NIA` |
 
 **Still open in phase C (pre-designsystem):** full designsystem / core.ui port.
@@ -405,16 +405,33 @@ Workspace: same **`forma-spike`** external tree.
 |------|--------|
 | Module | `core-analytics-android-util` — `AnalyticsHelper` / `AnalyticsEvent` / Stub + NoOp + `LocalAnalyticsHelper` |
 | Type | plain **`hiltAndroidUtil`** + Compose **runtime** library stack for CompositionLocal (**F18** sibling; `compose=false` target — F11) |
-| Bind | **StubAnalyticsHelper** for **all** product flavors (F27 prod `FirebaseAnalyticsHelper` + flavor source sets deferred) |
+| Bind (pre-F27) | **StubAnalyticsHelper** for all flavors until library flavors section |
 | Module | `core-notifications-res` **`androidRes`** + `core-notifications-android-util` **`hiltAndroidUtil`** |
 | **F31 / F23** | Tray strings + vector icon on **res** module (unique namespace `…notifications.res`); util imports `R as NotificationsR` — androidUtil still no `res/` |
-| Bind | **SystemTrayNotifier** for all flavors (validates res split + data edge; demo NoOp deferred with F27) |
+| Bind (pre-F27) | **SystemTrayNotifier** for all flavors until library flavors section |
 | Data | UserData toggles → analytics events; News `sync()` → notifier for new followed-topic items after onboard |
 | UI | `core-ui` → analytics; NewsFeed logs `news_resource_opened`; root `CompositionLocalProvider` + `TrackScreenViewEvent` |
 | Verify | `forma-spike` `:binary:assembleDemoDebug` + `:binary:assembleProdDebug` → **BUILD SUCCESSFUL** (645 tasks); APKs ~22 MB |
 | Version | `0.16.0-nia-forma-analytics-notifications` |
 
-**Still open in phase C:** F27 library flavors / prod Firebase analytics + demo NoOp notifier source sets; optional case-study Phase D.
+### Phase C — Library product flavors (F27) ✅ (2026-08-01)
+
+| Step | Result |
+|------|--------|
+| Engine | `AndroidLibraryFeatureConfiguration.productFlavors` + `LibraryExtension.applyProductFlavors(plan)` (no-op empty; `src/<flavor>/kotlin`; APK-only fields ignored) |
+| Model | Same **`FormaProductFlavor`** as binary — one global way; KDoc no longer binary-only |
+| DSL | `androidUtil` / `androidUtilTarget(productFlavors=…)` + thin `hiltAndroidUtil` forward |
+| Flavor-scoped deps | `NamedDependency.forProductFlavor` / `PlatformDependency.forProductFlavor` → `CustomConfiguration("${flavor}Implementation")`; preserves transitive + feature flags |
+| Unit tests | `FormaProductFlavorTest` library plan reuse; `DepsModelAndPluginHappyPathTest` flavor config mapping |
+| Spike analytics | `hiltAndroidUtil(productFlavors=demo+prod)`; Hilt modules in `src/demo` (Stub) / `src/prod` (Firebase + `FirebaseAnalyticsHelper`); `prod` BOM + analytics via `.forProductFlavor("prod")` |
+| Spike notifications | same flavors; `src/demo` NoOpNotifier bind / `src/prod` SystemTrayNotifier bind; main keeps implementations |
+| Spike sync | optional `prodImplementation` FCM via `.forProductFlavor("prod")` (deps-only; no new FCM source) |
+| Docs | `CALL-SITE-SURFACE.md` library flavors + flavor-scoped deps |
+| Verify | `plugins` `:android:test` + `:deps:test`; `publish-local 0.1.3-NIA`; spike `:binary:assembleDemoDebug` + `:binary:assembleProdDebug` |
+| Version | `0.17.0-nia-forma-library-flavors` |
+| **F27** | **closed** |
+
+**Still open:** Phase D case-study write-up (optional remaining Retrofit/prod network out of scope).
 
 ### Phase D — Case study write-up
 
@@ -453,7 +470,7 @@ Workspace: same **`forma-spike`** external tree.
 | F24 | 2026-07-31 | `deps()` overload mix | Cannot pass `.ksp` NamedDependency and `target()` FormaTarget in one `deps(...)` call (distinct overloads). Compose `transitiveDeps + deps(ksp) + deps(target)`. |
 | F25 | 2026-07-31 | Protobuf needs type-owned apply on JVM library | NiA `datastore-proto` is pure JVM + `com.google.protobuf`. Engine needed `libraryTarget` (like `androidUtilTarget`) so Path B `protobufLibrary` can pass derived type. Call sites stay attrs-only. |
 | F26 | 2026-07-31 | Proto lite supers on consumers | `UserPreferences` / enums extend protobuf lite; androidUtil consumer must `transitiveDeps(protobuf-kotlin-lite)` even when proto module already depends on it (project dep does not re-export non-api runtime the same way as NiA `api(libs.protobuf…)`). |
-| F27 | 2026-07-31 | Library product flavors / variant deps | Binary-only `FormaProductFlavor` closes F7 for APK. NiA also flavors libraries + `prodImplementation(FCM)` on sync + **analytics demo/prod binds** + **notifications demo NoOp / prod tray**. Spike binds Stub analytics + SystemTray notifier for **all** flavors until library flavor attrs exist. Future: optional library flavor attrs or type-owned missingDimensionStrategy — do **not** put free-form `android { productFlavors }` on every module. |
+| F27 | 2026-07-31 | Library product flavors / variant deps | **Closed 2026-08-01:** same `FormaProductFlavor` on `androidUtil` + `LibraryExtension.applyProductFlavors` + `src/<flavor>/kotlin`; flavor-scoped deps via `.forProductFlavor` → `prodImplementation`. Spike analytics demo Stub / prod Firebase; notifications demo NoOp / prod SystemTray; optional sync FCM prod dep. No raw `android { productFlavors }` at call sites. |
 
 ## Local reference commands
 
diff --git a/docs/PROGRESS.md b/docs/PROGRESS.md
index 9de4a758..c0f80e59 100644
--- a/docs/PROGRESS.md
+++ b/docs/PROGRESS.md
@@ -2,6 +2,30 @@
 
 Newest entries first.
 
+## 2026-08-01 — F-115: NiA dogfood library product flavors (F27)
+
+- **Ticket:** F-115 still `in_progress` · `priority: now` · `cron may continue` (Phase D case study next)
+- **Skills/modes:** Grok Build CLI `--mode full` (design/plan + implement + check) model `grok-4.5`; Hermes finish path (publish-local + spike verify + PROGRESS/PR)
+- **Engine (`plugins/`):**
+  - `LibraryExtension.applyProductFlavors` + `AndroidLibraryFeatureConfiguration.productFlavors` + flavor `src/<name>/kotlin` dirs
+  - DSL attr `productFlavors` on `androidUtil` / `androidUtilTarget` / `impl` / `androidApp` / `composeWidget` (empty default)
+  - `NamedDependency.forProductFlavor` / `PlatformDependency.forProductFlavor` → AGP `prodImplementation` via `CustomConfiguration` (no free-form config strings)
+  - Unit tests: `:android:test` + `:deps:test` **BUILD SUCCESSFUL**
+- **Publish:** `bash scripts/publish-local.sh 0.1.3-NIA` → mavenLocal
+- **External spike** `/Users/claw/work/nowinandroid-forma/forma-spike`:
+  - `niaContentTypeFlavors` shared list in forma-defs; forward on hilt wrappers
+  - analytics: demo Stub / prod FirebaseAnalyticsHelper + flavor-scoped BOM+analytics
+  - notifications: demo NoOp / prod SystemTray binds via flavor source sets
+  - intermediate consumers (data/domain/ui/features/root/sync) share library flavors for AGP variant match
+  - binary `0.17.0-nia-forma-library-flavors`
+- **Verify (real host):**
+  - `forma-spike` `./gradlew :binary:assembleDemoDebug :binary:assembleProdDebug` → **BUILD SUCCESSFUL** (945 tasks)
+  - APKs: `binary-demo-debug.apk` ~22 MB, `binary-prod-debug.apk` ~22 MB
+- **Docs:** CALL-SITE-SURFACE flavors F7+F27; DOGFOOD-NIA F27 closed; TICKETS F-115 Phase D next
+- **Commits/PRs:** this branch → PR base `v2`
+- **Blockers:** none product; F-094 Portal still human-blocked
+- **Next:** Phase D case study write-up (before/after LOC, config notes)
+
 ## 2026-08-01 — F-115: NiA dogfood core:analytics + core:notifications
 
 - **Ticket:** F-115 still `in_progress` · `priority: now` · `cron may continue` (F27 library flavors / Phase D next)
diff --git a/plugins/android/src/main/java/androidApp.kt b/plugins/android/src/main/java/androidApp.kt
index 30225a3a..5bce727c 100644
--- a/plugins/android/src/main/java/androidApp.kt
+++ b/plugins/android/src/main/java/androidApp.kt
@@ -7,6 +7,7 @@ import tools.forma.android.feature.kotlinAndroidFeatureDefinition
 import tools.forma.android.target.AndroidTargetRegistry
 import tools.forma.android.target.AndroidTargetTypes
 import tools.forma.android.utils.BuildConfiguration
+import tools.forma.android.utils.FormaProductFlavor
 import tools.forma.android.validation.disallowResources
 import tools.forma.android.visibility.Public
 import tools.forma.android.visibility.Visibility
@@ -43,6 +44,8 @@ fun Project.androidApp(
     manifestPlaceholders: Map<String, Any> = emptyMap(),
     /** Enable Jetpack Compose; defaults to project-wide `compose` setting. */
     compose: Boolean = Forma.settings.compose,
+    /** Library product flavors (F-115 / NiA F27); empty = unflavored. */
+    productFlavors: List<FormaProductFlavor> = emptyList(),
 ) {
 
     disallowResources()
@@ -58,6 +61,7 @@ fun Project.androidApp(
         manifestPlaceholders,
         selfValidator = selfV,
         compose = compose,
+        productFlavors = productFlavors,
     )
     applyFeatures(
         androidLibraryFeatureDefinition(libraryFeatureConfiguration),
diff --git a/plugins/android/src/main/java/androidUtil.kt b/plugins/android/src/main/java/androidUtil.kt
index 2b414be1..e9d6be76 100644
--- a/plugins/android/src/main/java/androidUtil.kt
+++ b/plugins/android/src/main/java/androidUtil.kt
@@ -1,4 +1,5 @@
 import tools.forma.android.target.AndroidTargetTypes
+import tools.forma.android.utils.FormaProductFlavor
 import tools.forma.owners.NoOwner
 import tools.forma.owners.Owner
 import tools.forma.android.visibility.Public
@@ -31,6 +32,12 @@ fun Project.androidUtil(
     testDependencies: FormaDependency = emptyDependency(),
     /** Enable Jetpack Compose; defaults to project-wide `compose` setting. */
     compose: Boolean = Forma.settings.compose,
+    /**
+     * Library product flavors (F-115 / NiA F27). Same [FormaProductFlavor] model as
+     * `androidBinary`; empty = unflavored. Pair with `NamedDependency.forProductFlavor` /
+     * `PlatformDependency.forProductFlavor` for AGP `prodImplementation` edges.
+     */
+    productFlavors: List<FormaProductFlavor> = emptyList(),
 ) {
     androidUtilTarget(
         type = AndroidTargetTypes.androidUtil,
@@ -40,5 +47,6 @@ fun Project.androidUtil(
         dependencies = dependencies,
         testDependencies = testDependencies,
         compose = compose,
+        productFlavors = productFlavors,
     )
 }
diff --git a/plugins/android/src/main/java/androidUtilTarget.kt b/plugins/android/src/main/java/androidUtilTarget.kt
index 4d35c3b5..ec98cbf4 100644
--- a/plugins/android/src/main/java/androidUtilTarget.kt
+++ b/plugins/android/src/main/java/androidUtilTarget.kt
@@ -4,6 +4,7 @@ import tools.forma.android.feature.applyFeatures
 import tools.forma.android.feature.kotlinAndroidFeatureDefinition
 import tools.forma.android.feature.processorConfigurationFeatures
 import tools.forma.android.target.AndroidTargetRegistry
+import tools.forma.android.utils.FormaProductFlavor
 import tools.forma.android.validation.disallowResources
 import tools.forma.android.visibility.Public
 import tools.forma.android.visibility.Visibility
@@ -25,6 +26,9 @@ import tools.forma.validation.validate
  * (e.g. dogfood `roomAndroidUtil`) so plugin identity stays on the type while the
  * AGP/util wiring is shared. Call sites of derived DSLs remain attributes-only —
  * never pass plugin ids here.
+ *
+ * [productFlavors] (F-115 / NiA F27): optional library product flavors using the
+ * same [FormaProductFlavor] model as `androidBinary`. Empty = unflavored.
  */
 fun Project.androidUtilTarget(
     type: TargetType,
@@ -35,6 +39,7 @@ fun Project.androidUtilTarget(
     testDependencies: FormaDependency = emptyDependency(),
     /** Enable Jetpack Compose; defaults to project-wide `compose` setting. */
     compose: Boolean = Forma.settings.compose,
+    productFlavors: List<FormaProductFlavor> = emptyList(),
 ) {
     disallowResources()
 
@@ -44,6 +49,7 @@ fun Project.androidUtilTarget(
     val androidFeatureConfig = AndroidLibraryFeatureConfiguration(
         packageName = packageName,
         compose = compose,
+        productFlavors = productFlavors,
     )
 
     applyFeatures(
diff --git a/plugins/android/src/main/java/composeWidget.kt b/plugins/android/src/main/java/composeWidget.kt
index 1a279528..a10a68fe 100644
--- a/plugins/android/src/main/java/composeWidget.kt
+++ b/plugins/android/src/main/java/composeWidget.kt
@@ -5,6 +5,7 @@ import tools.forma.android.feature.applyFeatures
 import tools.forma.android.feature.kotlinAndroidFeatureDefinition
 import tools.forma.android.target.AndroidTargetRegistry
 import tools.forma.android.target.AndroidTargetTypes
+import tools.forma.android.utils.FormaProductFlavor
 import tools.forma.android.visibility.Public
 import tools.forma.android.visibility.Visibility
 import tools.forma.deps.core.FormaDependency
@@ -32,7 +33,9 @@ fun Project.composeWidget(
     androidTestDependencies: FormaDependency = emptyDependency(),
     testInstrumentationRunner: String = androidJunitRunner,
     consumerMinificationFiles: Set<String> = emptySet(),
-    manifestPlaceholders: Map<String, Any> = emptyMap()
+    manifestPlaceholders: Map<String, Any> = emptyMap(),
+    /** Library product flavors (F-115 / NiA F27); empty = unflavored. */
+    productFlavors: List<FormaProductFlavor> = emptyList(),
 ) {
     val selfV = AndroidTargetRegistry.selfValidator(AndroidTargetTypes.composeWidget).asValidator()
     selfV.validate(target)
@@ -44,6 +47,7 @@ fun Project.composeWidget(
         consumerMinificationFiles = consumerMinificationFiles,
         manifestPlaceholders = manifestPlaceholders,
         compose = true,
+        productFlavors = productFlavors,
         selfValidator = selfV
     )
 
diff --git a/plugins/android/src/main/java/impl.kt b/plugins/android/src/main/java/impl.kt
index 922cc911..abe368dd 100644
--- a/plugins/android/src/main/java/impl.kt
+++ b/plugins/android/src/main/java/impl.kt
@@ -7,6 +7,7 @@ import tools.forma.android.feature.kotlinAndroidFeatureDefinition
 import tools.forma.android.target.AndroidTargetRegistry
 import tools.forma.android.target.AndroidTargetTypes
 import tools.forma.android.utils.BuildConfiguration
+import tools.forma.android.utils.FormaProductFlavor
 import tools.forma.deps.core.FormaDependency
 import tools.forma.deps.core.applyDependencies
 import tools.forma.deps.core.applyTargetPlugins
@@ -29,6 +30,8 @@ import tools.forma.validation.validate
  *   use the dedicated `viewBinding` target type instead (always on).
  * @param compose enable Jetpack Compose for this target; defaults to project-wide
  *   [androidProjectConfiguration] `compose` flag.
+ * @param productFlavors optional library product flavors (F-115 / NiA F27); empty = unflavored.
+ *   Required when this impl depends on flavored libraries (matching AGP dimensions).
  */
 fun Project.impl(
     packageName: String,
@@ -45,7 +48,8 @@ fun Project.impl(
     testInstrumentationRunner: String = androidJunitRunner,
     buildConfiguration: BuildConfiguration = BuildConfiguration(),
     consumerMinificationFiles: Set<String> = emptySet(),
-    manifestPlaceholders: Map<String, Any> = emptyMap()
+    manifestPlaceholders: Map<String, Any> = emptyMap(),
+    productFlavors: List<FormaProductFlavor> = emptyList(),
 ) {
 
     val selfV = AndroidTargetRegistry.selfValidator(AndroidTargetTypes.impl).asValidator()
@@ -59,7 +63,8 @@ fun Project.impl(
         manifestPlaceholders,
         selfValidator = selfV,
         viewBinding = viewBinding,
-        compose = compose
+        compose = compose,
+        productFlavors = productFlavors,
     )
     applyFeatures(
         androidLibraryFeatureDefinition(libraryFeatureConfiguration),
diff --git a/plugins/android/src/main/java/tools/forma/android/feature/AndroidBinary.kt b/plugins/android/src/main/java/tools/forma/android/feature/AndroidBinary.kt
index af0073e4..ae9c9dda 100644
--- a/plugins/android/src/main/java/tools/forma/android/feature/AndroidBinary.kt
+++ b/plugins/android/src/main/java/tools/forma/android/feature/AndroidBinary.kt
@@ -24,8 +24,9 @@ import tools.forma.validation.validator
  * [signingConfigs] / [buildTypeSigning] are **per-binary** (F-097 / GH #51) —
  * APK signing identity lives only on the composition root, not on library shells.
  *
- * [productFlavors] are **per-binary** (F-115 / NiA F7) — flavor dimensions live
- * on the APK root only in v1; [BuildConfiguration] stays build-types only.
+ * [productFlavors] on the APK root (F-115 / NiA F7). Libraries that need matching
+ * dimensions use the same [FormaProductFlavor] list on `androidUtil` (F27);
+ * [BuildConfiguration] stays build-types only.
  */
 data class AndroidBinaryFeatureConfiguration(
     val packageName: String,
diff --git a/plugins/android/src/main/java/tools/forma/android/feature/AndroidLibrary.kt b/plugins/android/src/main/java/tools/forma/android/feature/AndroidLibrary.kt
index 9f5e8ba8..b3105fde 100644
--- a/plugins/android/src/main/java/tools/forma/android/feature/AndroidLibrary.kt
+++ b/plugins/android/src/main/java/tools/forma/android/feature/AndroidLibrary.kt
@@ -4,8 +4,10 @@ import androidJunitRunner
 import com.android.build.api.dsl.LibraryExtension
 import tools.forma.android.target.LibraryTargetTemplate
 import tools.forma.android.utils.BuildConfiguration
+import tools.forma.android.utils.FormaProductFlavor
 import tools.forma.android.utils.applyCoreLibraryDesugaring
 import tools.forma.android.utils.applyFrom
+import tools.forma.android.utils.applyProductFlavors
 import tools.forma.validation.Validator
 import tools.forma.validation.validator
 
@@ -18,6 +20,12 @@ class AndroidLibraryFeatureConfiguration(
     val viewBinding: Boolean = false,
     /** Enable Jetpack Compose for this Android library target. */
     val compose: Boolean = false,
+    /**
+     * Product flavors for this library (optional; F-115 / NiA F27).
+     * Empty = unflavored (default). Same [FormaProductFlavor] model as `androidBinary`;
+     * APK-only fields are ignored on library apply.
+     */
+    val productFlavors: List<FormaProductFlavor> = emptyList(),
     val selfValidator: Validator = validator(LibraryTargetTemplate)
 )
 
@@ -49,6 +57,9 @@ fun androidLibraryFeatureDefinition(
             sourceSets.getByName("androidTest").java.srcDir("src/androidTest/kotlin")
 
             buildTypes.applyFrom(feature.buildConfiguration)
+            // Product flavors after build types (empty = unflavored library).
+            // Also registers src/<flavor>/kotlin on each flavor source set.
+            applyProductFlavors(feature.productFlavors)
             compileOptions.applyFrom(formaConfiguration)
             applyCoreLibraryDesugaring(project, formaConfiguration)
 
diff --git a/plugins/android/src/main/java/tools/forma/android/utils/FormaProductFlavor.kt b/plugins/android/src/main/java/tools/forma/android/utils/FormaProductFlavor.kt
index 18ce00d2..72150cf2 100644
--- a/plugins/android/src/main/java/tools/forma/android/utils/FormaProductFlavor.kt
+++ b/plugins/android/src/main/java/tools/forma/android/utils/FormaProductFlavor.kt
@@ -2,24 +2,31 @@ package tools.forma.android.utils
 
 import com.android.build.api.dsl.ApplicationExtension
 import com.android.build.api.dsl.ApplicationProductFlavor
+import com.android.build.api.dsl.LibraryExtension
 import com.android.build.api.dsl.ProductFlavor
 
 /**
- * Typed product-flavor identity for `androidBinary` (F-115 / NiA F7 dogfood).
+ * Typed product-flavor identity for Forma Android targets (F-115 / NiA F7 + F27).
  *
- * **Binary-only (v1):** product flavors are composition-root config — same placement
- * rationale as [FormaSigningConfig] (F-097) and versionCode/Name (F-092). They are
- * **not** stuffed into [BuildConfiguration] (build-types only) and are **not** a
- * library/impl shopping API.
+ * **Same model for binary and library:** [FormaProductFlavor] is the one global way
+ * to declare flavor dimensions. Composition-root APKs use it on `androidBinary`;
+ * library targets that go through [tools.forma.android.feature.androidLibraryFeatureDefinition]
+ * (e.g. `androidUtil`) accept the same list.
  *
- * Multi-module flavor dimensions (library `productFlavors` + `demoImplementation`
- * edges) stay out of v1: AGP accepts unflavored library deps against a flavored
- * application. Document gaps rather than invent dual happy paths.
+ * Libraries **ignore** APK-only fields ([applicationIdSuffix], [versionNameSuffix]) —
+ * [applyFormaProductFlavor] only writes those onto [ApplicationProductFlavor].
+ * [BuildConfiguration] stays build-types only (flavors are not stuffed into it).
+ *
+ * Empty list (default) = unflavored target so existing samples stay unchanged.
+ * Flavor-scoped external deps use `NamedDependency.forProductFlavor` /
+ * `PlatformDependency.forProductFlavor` → AGP `prodImplementation` etc.
+ * (see `docs/CALL-SITE-SURFACE.md`).
  *
  * @param name flavor name (`demo`, `prod`, …)
  * @param dimension flavor dimension name (`contentType`, …)
- * @param applicationIdSuffix optional APK id suffix (e.g. `".demo"`); null = none
- * @param versionNameSuffix optional versionName suffix; null = none
+ * @param applicationIdSuffix optional APK id suffix (e.g. `".demo"`); null = none;
+ *   ignored on library targets
+ * @param versionNameSuffix optional versionName suffix; null = none; ignored on libraries
  * @param matchingFallbacks optional AGP matchingFallbacks for this flavor
  * @param manifestPlaceholders extra placeholders merged onto this flavor
  * @param buildConfigFields optional BuildConfig field map (name → value expression)
@@ -55,8 +62,7 @@ data class BuildConfigField(
 /**
  * Pure plan for AGP apply: ordered unique dimensions + flavors.
  *
- * @throws IllegalArgumentException on blank names, duplicate flavor names, or
- *   empty non-null lists that would create a half-configured dimension set
+ * @throws IllegalArgumentException on blank names or duplicate flavor names
  */
 fun resolveProductFlavorPlan(
     flavors: List<FormaProductFlavor>,
@@ -67,7 +73,7 @@ fun resolveProductFlavorPlan(
     flavors.forEach { flavor ->
         require(flavor.name !in names) {
             "Duplicate product flavor name '${flavor.name}' " +
-                "(each name may appear once on androidBinary)"
+                "(each name may appear once per target)"
         }
         names += flavor.name
         dimensions += flavor.dimension
@@ -104,6 +110,27 @@ fun ApplicationExtension.applyProductFlavors(plan: ProductFlavorPlan) {
     }
 }
 
+/**
+ * Applies [ProductFlavorPlan] onto AGP [LibraryExtension] flavor containers and
+ * registers `src/<flavor>/kotlin` on each flavor source set.
+ *
+ * No-op when the plan is empty (default library call sites). Does **not** require
+ * [ApplicationProductFlavor] fields — APK-only attrs are skipped by
+ * [applyFormaProductFlavor].
+ */
+fun LibraryExtension.applyProductFlavors(plan: ProductFlavorPlan) {
+    if (plan.flavors.isEmpty()) return
+    flavorDimensions.clear()
+    flavorDimensions.addAll(plan.dimensions)
+    plan.flavors.forEach { forma ->
+        val existing = productFlavors.findByName(forma.name)
+        val flavor = existing ?: productFlavors.create(forma.name)
+        applyFormaProductFlavor(flavor, forma)
+        // Kotlin sources under src/<flavor>/kotlin (parity with main/test wiring).
+        sourceSets.maybeCreate(forma.name).java.srcDir("src/${forma.name}/kotlin")
+    }
+}
+
 /** Writes one [FormaProductFlavor] onto an AGP [ProductFlavor] / application flavor. */
 fun applyFormaProductFlavor(target: ProductFlavor, forma: FormaProductFlavor) {
     target.dimension = forma.dimension
@@ -129,3 +156,11 @@ fun applyFormaProductFlavor(target: ProductFlavor, forma: FormaProductFlavor) {
 fun ApplicationExtension.applyProductFlavors(flavors: List<FormaProductFlavor>) {
     applyProductFlavors(resolveProductFlavorPlan(flavors))
 }
+
+/**
+ * Convenience: resolve + apply in one step for library feature definition.
+ * Empty [flavors] is a no-op (keeps unflavored libraries working).
+ */
+fun LibraryExtension.applyProductFlavors(flavors: List<FormaProductFlavor>) {
+    applyProductFlavors(resolveProductFlavorPlan(flavors))
+}
diff --git a/plugins/android/src/test/kotlin/tools/forma/android/utils/FormaProductFlavorTest.kt b/plugins/android/src/test/kotlin/tools/forma/android/utils/FormaProductFlavorTest.kt
index 1e44c99e..e15d7ee7 100644
--- a/plugins/android/src/test/kotlin/tools/forma/android/utils/FormaProductFlavorTest.kt
+++ b/plugins/android/src/test/kotlin/tools/forma/android/utils/FormaProductFlavorTest.kt
@@ -6,8 +6,8 @@ import kotlin.test.assertFailsWith
 import kotlin.test.assertTrue
 
 /**
- * Pure unit coverage for binary product-flavor model (F-115 / NiA F7).
- * No Gradle Project / AGP containers.
+ * Pure unit coverage for product-flavor model (F-115 / NiA F7 + F27 library reuse).
+ * No Gradle Project / AGP containers — plan resolution is shared by binary and library.
  */
 class FormaProductFlavorTest {
 
@@ -109,4 +109,20 @@ class FormaProductFlavorTest {
             plan.flavors[0].buildConfigFields["NIA_CONTENT_TYPE"],
         )
     }
+
+    @Test
+    fun `library plan reuses same resolve as binary — APK-only fields stay on model`() {
+        // Libraries pass the same FormaProductFlavor list; applyFormaProductFlavor
+        // skips applicationIdSuffix on non-ApplicationProductFlavor. Plan is identical.
+        val libraryCallSite = listOf(
+            FormaProductFlavor(name = "demo", dimension = "contentType", applicationIdSuffix = ".demo"),
+            FormaProductFlavor(name = "prod", dimension = "contentType"),
+        )
+        val plan = resolveProductFlavorPlan(libraryCallSite)
+        assertEquals(ProductFlavorPlan.EMPTY, resolveProductFlavorPlan(emptyList()))
+        assertEquals(listOf("contentType"), plan.dimensions)
+        assertEquals(listOf("demo", "prod"), plan.flavors.map { it.name })
+        // Model still carries APK suffix (binary may share the list); library apply ignores it.
+        assertEquals(".demo", plan.flavors[0].applicationIdSuffix)
+    }
 }
diff --git a/plugins/deps/src/main/java/dependencies.kt b/plugins/deps/src/main/java/dependencies.kt
index fdec8620..072f4c9c 100644
--- a/plugins/deps/src/main/java/dependencies.kt
+++ b/plugins/deps/src/main/java/dependencies.kt
@@ -24,6 +24,7 @@ import tools.forma.deps.core.TargetDependency
 import tools.forma.deps.core.TargetSpec
 import tools.forma.deps.core.USE_FEATURE_STUBS_FLAG
 import tools.forma.deps.core.featureImplementationPair
+import tools.forma.deps.core.productFlavorImplementation
 import tools.forma.target.FormaTarget
 
 /**
@@ -233,6 +234,52 @@ fun NamedDependency.whenFlag(flag: String, enabled: Boolean = true): NamedDepend
         }
     )
 
+/**
+ * Map every name spec onto AGP `{flavor}Implementation` (F-115 / NiA F27).
+ *
+ * Preserves [NameSpec.transitive] and feature-flag gating. Compose with [plus]:
+ *
+ * ```kotlin
+ * dependencies = deps(target(":core:model:library")) +
+ *     transitiveDeps("com.google.firebase:firebase-analytics").forProductFlavor("prod") +
+ *     transitivePlatform("com.google.firebase:firebase-bom:33.16.0").forProductFlavor("prod")
+ * ```
+ *
+ * Requires matching [tools.forma.android.utils.FormaProductFlavor] on the library target
+ * so AGP creates the configuration. Do **not** scatter free-form config name strings.
+ */
+fun NamedDependency.forProductFlavor(flavor: String): NamedDependency {
+    val config = productFlavorImplementation(flavor)
+    return NamedDependency(
+        names.map { spec ->
+            NameSpec(
+                name = spec.name,
+                config = config,
+                transitive = spec.transitive,
+                featureFlag = spec.featureFlag,
+                featureFlagExpected = spec.featureFlagExpected,
+            )
+        }
+    )
+}
+
+/**
+ * Map every platform (BOM) spec onto AGP `{flavor}Implementation` (F-115 / NiA F27).
+ * Preserves [PlatformSpec.transitive]. See [NamedDependency.forProductFlavor].
+ */
+fun PlatformDependency.forProductFlavor(flavor: String): PlatformDependency {
+    val config = productFlavorImplementation(flavor)
+    return PlatformDependency(
+        names.map { spec ->
+            PlatformSpec(
+                name = spec.name,
+                config = config,
+                transitive = spec.transitive,
+            )
+        }
+    )
+}
+
 /**
  * Gate every target spec in this [TargetDependency] on project-global feature flag [flag]
  * (F-104 / GH #43). Same apply-time resolution as [NamedDependency.whenFlag].
diff --git a/plugins/deps/src/main/java/tools.forma/deps/core/ConfigurationType.kt b/plugins/deps/src/main/java/tools.forma/deps/core/ConfigurationType.kt
index e39063bb..273794bd 100644
--- a/plugins/deps/src/main/java/tools.forma/deps/core/ConfigurationType.kt
+++ b/plugins/deps/src/main/java/tools.forma/deps/core/ConfigurationType.kt
@@ -30,6 +30,22 @@ object Ksp : ConfigurationType {
 
 @JvmInline value class CustomConfiguration(override val name: String) : ConfigurationType
 
+/**
+ * AGP product-flavor implementation configuration name (`prodImplementation`, …).
+ *
+ * Pure helper for F-115 / NiA F27 flavor-scoped external deps. Prefer
+ * [NamedDependency.forProductFlavor] / [PlatformDependency.forProductFlavor] at
+ * call sites rather than free-form configuration strings.
+ *
+ * @throws IllegalArgumentException when [flavor] is blank
+ */
+fun productFlavorImplementation(flavor: String): CustomConfiguration {
+    require(flavor.isNotBlank()) {
+        "product flavor name for configuration must not be blank"
+    }
+    return CustomConfiguration("${flavor}Implementation")
+}
+
 sealed class DepSpec(val config: ConfigurationType)
 
 /**
diff --git a/plugins/deps/src/test/kotlin/tools/forma/deps/core/DepsModelAndPluginHappyPathTest.kt b/plugins/deps/src/test/kotlin/tools/forma/deps/core/DepsModelAndPluginHappyPathTest.kt
index 77a68bb5..88f971c3 100644
--- a/plugins/deps/src/test/kotlin/tools/forma/deps/core/DepsModelAndPluginHappyPathTest.kt
+++ b/plugins/deps/src/test/kotlin/tools/forma/deps/core/DepsModelAndPluginHappyPathTest.kt
@@ -6,12 +6,14 @@ import kotlin.test.assertEquals
 import kotlin.test.assertSame
 import kotlin.test.assertTrue
 import dep
+import forProductFlavor
 import ksp
 import plus
 import tools.forma.core.target.targetType
 import transitiveDep
 import transitiveDeps
 import tools.forma.deps.core.CompileOnly
+import tools.forma.deps.core.CustomConfiguration
 import tools.forma.deps.core.EmptyDependency
 import tools.forma.deps.core.FileDependency
 import tools.forma.deps.core.FileSpec
@@ -24,6 +26,7 @@ import tools.forma.deps.core.PlatformDependency
 import tools.forma.deps.core.PlatformSpec
 import tools.forma.deps.core.TargetPluginRegistry
 import tools.forma.deps.core.deriveTargetType
+import tools.forma.deps.core.productFlavorImplementation
 import tools.forma.deps.core.registerTargetPlugin
 import tools.forma.deps.core.targetPlugin
 import tools.forma.deps.core.DefaultTargetPluginRegistry
@@ -92,6 +95,71 @@ class DepsModelAndPluginHappyPathTest {
         assertTrue(mixed.dependency.any { it is NameSpec })
     }
 
+    @Test
+    fun `productFlavorImplementation maps to AGP flavor Implementation config`() {
+        assertEquals("prodImplementation", productFlavorImplementation("prod").name)
+        assertEquals("demoImplementation", productFlavorImplementation("demo").name)
+        assertFailsWithBlankFlavor()
+    }
+
+    private fun assertFailsWithBlankFlavor() {
+        try {
+            productFlavorImplementation(" ")
+            throw AssertionError("expected blank flavor to fail")
+        } catch (e: IllegalArgumentException) {
+            assertTrue(e.message!!.contains("blank"))
+        }
+    }
+
+    @Test
+    fun `NamedDependency forProductFlavor remaps config and preserves transitive + flags`() {
+        val flagged =
+            NamedDependency(
+                listOf(
+                    NameSpec(
+                        name = "com.google.firebase:firebase-analytics",
+                        config = Implementation,
+                        transitive = true,
+                        featureFlag = "useFirebase",
+                        featureFlagExpected = true,
+                    ),
+                ),
+            ).forProductFlavor("prod")
+        val spec = flagged.names.single()
+        assertEquals("com.google.firebase:firebase-analytics", spec.name)
+        assertEquals(CustomConfiguration("prodImplementation"), spec.config)
+        assertEquals("prodImplementation", spec.config.name)
+        assertTrue(spec.transitive)
+        assertEquals("useFirebase", spec.featureFlag)
+        assertEquals(true, spec.featureFlagExpected)
+    }
+
+    @Test
+    fun `PlatformDependency forProductFlavor remaps BOM config and preserves transitive`() {
+        val bom =
+            PlatformDependency(
+                listOf(PlatformSpec("com.google.firebase:firebase-bom:33.16.0", Implementation, transitive = true)),
+            ).forProductFlavor("prod")
+        val spec = bom.names.single()
+        assertEquals("com.google.firebase:firebase-bom:33.16.0", spec.name)
+        assertEquals(CustomConfiguration("prodImplementation"), spec.config)
+        assertTrue(spec.transitive)
+    }
+
+    @Test
+    fun `forProductFlavor composes with plus for NiA prod stack`() {
+        val stack =
+            transitiveDeps("com.google.firebase:firebase-analytics").forProductFlavor("prod") +
+                PlatformDependency(
+                    listOf(PlatformSpec("com.google.firebase:firebase-bom:33.16.0", Implementation)),
+                ).forProductFlavor("prod")
+        assertEquals(1, stack.names.size)
+        assertEquals(1, stack.platforms.size)
+        assertEquals("prodImplementation", stack.names.single().config.name)
+        assertEquals("prodImplementation", stack.platforms.single().config.name)
+        assertTrue(stack.names.single().transitive)
+    }
+
     @Test
     fun `dependency model constructors preserve specs`() {
         val name = NameSpec("g:a:1", Implementation, transitive = true)