fix(boundaries): allow feature-to-feature imports of public exports

turbo.json's boundary config already allows `feature -> feature`, and
the cross-feature event system depends on it — a consumer must import
the publisher's event contract from `@repo/<publisher>`. But the ESLint
boundaries config, ADR-010, and AGENTS.md still declared
`feature -> [core, tooling]`, contradicting turbo.json and the shipped
code (marketing-pages imports @repo/auth).

Align all three to turbo.json: a feature may import another feature's
published public exports. Internals stay sealed by the `exports` map,
and cross-feature behaviour still flows through IEventBus.

AGENTS.md

@@ -64,7 +64,7 @@ See `docs/guides/runbook.md` for the full workflow.
 | app              | app, core, core-composition, feature, tooling |
 | core-composition | core, core-composition, feature, tooling      |
 | core             | core, core-composition, tooling               |
-| feature          | core, tooling                                 |
+| feature          | core, feature, tooling                        |
 | tooling          | tooling                                       |
 
 ### Composition exceptions
@@ -81,7 +81,7 @@ No other cross-package boundary deviations are permitted.
 2. **`exports` maps** — feature packages expose `.`, `./ui`, `./cms`, `./api`, `./di/bind-production`, `./di/bind-dev-seed` only; no deep source paths exist.
 3. **ESLint `eslint-plugin-boundaries`** (lint-time) — configured in `packages/core-eslint/`:
    - Enforces the five-tag rules at linting
-   - Feature packages may import from `core` and tooling only.
+   - Feature packages may import from `core`, tooling, and other features' public exports (the `@repo/<feature>` contract barrel — e.g. an event contract a consumer subscribes to). They must not reach another feature's internals (the `exports` map seals those) or call its use cases directly — cross-feature behaviour flows through `IEventBus`.
    - `core-shared`, `core-ui` may not import any feature.
    - `core-api` restricted to `@repo/<feature>/api` imports.
    - `core-cms` restricted to `@repo/<feature>/cms` imports.

docs/decisions/adr-010-turbo-boundaries.md

@@ -38,6 +38,7 @@ ADR-006 mentioned three tags. This ADR refines the model to five, distinguishing
 - **tooling** — `packages/core-eslint`, `core-typescript`
 
 Why `core-trpc` is `core-composition`:
+
 - `core-trpc` imports `@repo/core-api` (the tRPC app router)
 - `core-api` imports feature routers from `@repo/<feature>/api`
 - Therefore, `core-trpc` transitively depends on features through the `AppRouter` type
@@ -51,17 +52,40 @@ Why `core-trpc` is `core-composition`:
    {
      "boundaries": {
        "tags": {
-         "app": { "dependencies": { "allow": ["app", "core", "core-composition", "feature", "tooling"] } },
+         "app": {
-         "core-composition": { "dependencies": { "allow": ["core", "core-composition", "feature", "tooling"] } },
+           "dependencies": {
-         "core": { "dependencies": { "allow": ["core", "core-composition", "tooling"] } },
+             "allow": ["app", "core", "core-composition", "feature", "tooling"]
-         "feature": { "dependencies": { "allow": ["core", "tooling"] } },
+           }
+         },
+         "core-composition": {
+           "dependencies": {
+             "allow": ["core", "core-composition", "feature", "tooling"]
+           }
+         },
+         "core": {
+           "dependencies": { "allow": ["core", "core-composition", "tooling"] }
+         },
+         "feature": {
+           "dependencies": { "allow": ["core", "feature", "tooling"] }
+         },
          "tooling": { "dependencies": { "allow": ["tooling"] } }
        }
      }
    }
    ```
 
+> **Amendment (2026-05-21) — feature → feature.** The `feature` tag's allow-list
+> includes `feature`. A feature package may depend on another feature's
+> _published public exports_ — the `@repo/<feature>` contract barrel (types,
+> schemas, errors, event contracts). This is required by the cross-feature
+> event system (ADR-015): a consumer must import the publisher's event
+> contract. Two guardrails remain: each feature's `exports` map seals its
+> internals (only `.`, `./ui`, `./api`, `./cms`, `./di/bind-*` are reachable),
+> and cross-feature _behaviour_ still flows through `IEventBus` — a feature
+> never imports and invokes another feature's use cases directly.
+
 2. **Per-package `turbo.json`** declares the package's tag:
+
    ```json
    // packages/blog/turbo.json
    { "extends": ["../../../turbo.json"], "tasks": { /* ... */ } }
@@ -76,11 +100,12 @@ Why `core-trpc` is `core-composition`:
 Both ESLint and Turborepo enforce the same five-tag rules, but for different reasons:
 
 | Layer                             | Runs             | Sees                                                    | Exempts via                        |
-|---|---|---|---|
+| --------------------------------- | ---------------- | ------------------------------------------------------- | ---------------------------------- |
 | ESLint `eslint-plugin-boundaries` | lint-time        | Direct imports per file                                 | `// @boundaries-ignore` comments   |
 | Turborepo `boundaries`            | build-graph time | Entire workspace dependency graph including transitives | None (graph-based, not per-import) |
 
 **Why both?**
+
 - **ESLint** provides fine-grained control (file-level exemptions) and immediate feedback during development
 - **Turborepo** catches transitive issues (e.g., feature reach through composition packages) and missing declarations
 

packages/core-eslint/base.js

@@ -96,7 +96,7 @@ export default [
               from: "app",
               allow: ["app", "core", "core-composition", "feature", "tooling"],
             },
-            { from: "feature", allow: ["core", "tooling"] },
+            { from: "feature", allow: ["core", "feature", "tooling"] },
             { from: "core", allow: ["core", "tooling"] },
             { from: "core-composition", allow: ["core", "feature", "tooling"] },
             { from: "tooling", allow: ["tooling"] },