feat(ai-credits): role-scoped purchasable credit packages

Adds applicable_roles TEXT[] to ai_credit_packages (empty = visible to
every role, matching today's behavior for the 4 existing packages -
nothing changes for them until an admin opts them into specific
roles). Mirrors pricing_packages' existing role_key convention, as an
array since one AI package can reasonably apply to several roles at
once.

- GET /api/ai-credits (list_packages) now accepts optional auth (via a
  local MaybeAuthUser wrapper, since AuthUser doesn't implement axum's
  optional-extraction trait) and filters out packages not applicable
  to the viewer's roles. Anonymous viewers only see role-unrestricted
  packages.
- POST /api/ai-credits/order (create_order) re-validates role
  eligibility server-side too, not just in the listing - closes off
  a logged-in user buying a package never shown to them.
- Admin CRUD (GET/POST /api/admin/ai-credits/packages,
  PATCH .../{id}) now reads/writes applicable_roles.

Applied to nxtgauge_test and prod; verified column + index created,
existing 4 packages default to empty (all roles).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/payments/src/ai_credits.rs

@@ -11,8 +11,8 @@
 use crate::payu;
 use crate::AppState;
 use axum::{
-    extract::{Path, State},
-    http::StatusCode,
+    extract::{FromRequestParts, Path, State},
+    http::{request::Parts, StatusCode},
     routing::{get, patch, post},
     Json, Router,
 };
@@ -22,6 +22,20 @@ use serde::{Deserialize, Serialize};
 use sqlx::{FromRow, PgPool};
 use uuid::Uuid;
 
+/// AuthUser doesn't implement axum's optional-extraction trait, so a bare
+/// `Option<AuthUser>` handler param won't compile - this wraps it manually.
+/// Used by list_packages, which needs to know the viewer's role when logged
+/// in but must still work for anonymous/logged-out browsing.
+struct MaybeAuthUser(Option<AuthUser>);
+
+impl<S: Send + Sync> FromRequestParts<S> for MaybeAuthUser {
+    type Rejection = std::convert::Infallible;
+
+    async fn from_request_parts(parts: &mut Parts, state: &S) -> Result<Self, Self::Rejection> {
+        Ok(MaybeAuthUser(AuthUser::from_request_parts(parts, state).await.ok()))
+    }
+}
+
 pub fn router() -> Router<AppState> {
     Router::new()
         .route("/", get(list_packages))
@@ -47,6 +61,7 @@ struct AiCreditPackageRow {
     description: Option<String>,
     credits: i32,
     price_inr: i32,
+    applicable_roles: Vec<String>,
 }
 
 #[derive(Serialize)]
@@ -54,14 +69,36 @@ struct ListPackagesResponse {
     packages: Vec<AiCreditPackageRow>,
 }
 
-async fn list_packages(State(state): State<AppState>) -> Result<Json<ListPackagesResponse>, (StatusCode, String)> {
+/// A package with an empty applicable_roles is visible to everyone (the
+/// default, matching pre-role-scoping behavior); otherwise the viewer must
+/// hold at least one of the listed roles. Logged-out/anonymous viewers only
+/// ever see role-unrestricted packages.
+fn package_visible_to(applicable_roles: &[String], viewer_roles: Option<&[String]>) -> bool {
+    if applicable_roles.is_empty() {
+        return true;
+    }
+    viewer_roles
+        .map(|roles| roles.iter().any(|r| applicable_roles.iter().any(|ar| ar.eq_ignore_ascii_case(r))))
+        .unwrap_or(false)
+}
+
+async fn list_packages(
+    MaybeAuthUser(auth): MaybeAuthUser,
+    State(state): State<AppState>,
+) -> Result<Json<ListPackagesResponse>, (StatusCode, String)> {
     let packages = sqlx::query_as::<_, AiCreditPackageRow>(
-        "SELECT id, name, description, credits, price_inr FROM ai_credit_packages WHERE is_active = TRUE ORDER BY price_inr",
+        "SELECT id, name, description, credits, price_inr, applicable_roles FROM ai_credit_packages WHERE is_active = TRUE ORDER BY price_inr",
     )
     .fetch_all(&state.pool)
     .await
     .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("DB error: {e}")))?;
 
+    let viewer_roles = auth.as_ref().map(|a| a.claims.roles.as_slice());
+    let packages = packages
+        .into_iter()
+        .filter(|p| package_visible_to(&p.applicable_roles, viewer_roles))
+        .collect();
+
     Ok(Json(ListPackagesResponse { packages }))
 }
 
@@ -95,6 +132,7 @@ struct AiCreditPackagePriceRow {
     name: String,
     credits: i32,
     price_inr: i32,
+    applicable_roles: Vec<String>,
 }
 
 #[derive(Debug, FromRow)]
@@ -191,7 +229,7 @@ async fn create_order(
         .map_err(|_| (StatusCode::BAD_REQUEST, "Invalid package id".to_string()))?;
 
     let package = sqlx::query_as::<_, AiCreditPackagePriceRow>(
-        "SELECT name, credits, price_inr FROM ai_credit_packages WHERE id = $1 AND is_active = TRUE",
+        "SELECT name, credits, price_inr, applicable_roles FROM ai_credit_packages WHERE id = $1 AND is_active = TRUE",
     )
     .bind(package_id)
     .fetch_optional(&state.pool)
@@ -199,6 +237,12 @@ async fn create_order(
     .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("DB error: {e}")))?
     .ok_or((StatusCode::BAD_REQUEST, "Invalid or inactive AI credit package".to_string()))?;
 
+    // Enforce role scoping server-side too, not just in the listing - a
+    // logged-in user could otherwise buy a package never shown to them.
+    if !package_visible_to(&package.applicable_roles, Some(auth.claims.roles.as_slice())) {
+        return Err((StatusCode::FORBIDDEN, "This package is not available for your role".to_string()));
+    }
+
     let contact = sqlx::query_as::<_, UserContactRow>("SELECT email, full_name, phone FROM users WHERE id = $1")
         .bind(auth.user_id)
         .fetch_optional(&state.pool)
@@ -433,6 +477,7 @@ struct AdminAiCreditPackageRow {
     credits: i32,
     price_inr: i32,
     is_active: bool,
+    applicable_roles: Vec<String>,
     created_at: chrono::DateTime<chrono::Utc>,
     updated_at: chrono::DateTime<chrono::Utc>,
 }
@@ -449,7 +494,7 @@ async fn admin_list_packages(
     require_admin(&auth).map_err(|_| (StatusCode::FORBIDDEN, "Admin access required".to_string()))?;
 
     let packages = sqlx::query_as::<_, AdminAiCreditPackageRow>(
-        "SELECT id, name, description, credits, price_inr, is_active, created_at, updated_at FROM ai_credit_packages ORDER BY price_inr",
+        "SELECT id, name, description, credits, price_inr, is_active, applicable_roles, created_at, updated_at FROM ai_credit_packages ORDER BY price_inr",
     )
     .fetch_all(&state.pool)
     .await
@@ -464,6 +509,8 @@ struct CreatePackageRequest {
     description: Option<String>,
     credits: i32,
     price_inr: i32,
+    #[serde(default)]
+    applicable_roles: Vec<String>,
 }
 
 async fn admin_create_package(
@@ -479,15 +526,16 @@ async fn admin_create_package(
 
     let package = sqlx::query_as::<_, AdminAiCreditPackageRow>(
         r#"
-        INSERT INTO ai_credit_packages (name, description, credits, price_inr)
-        VALUES ($1, $2, $3, $4)
-        RETURNING id, name, description, credits, price_inr, is_active, created_at, updated_at
+        INSERT INTO ai_credit_packages (name, description, credits, price_inr, applicable_roles)
+        VALUES ($1, $2, $3, $4, $5)
+        RETURNING id, name, description, credits, price_inr, is_active, applicable_roles, created_at, updated_at
         "#,
     )
     .bind(&body.name)
     .bind(&body.description)
     .bind(body.credits)
     .bind(body.price_inr)
+    .bind(&body.applicable_roles)
     .fetch_one(&state.pool)
     .await
     .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("DB error: {e}")))?;
@@ -502,6 +550,7 @@ struct UpdatePackageRequest {
     credits: Option<i32>,
     price_inr: Option<i32>,
     is_active: Option<bool>,
+    applicable_roles: Option<Vec<String>>,
 }
 
 async fn admin_update_package(
@@ -524,9 +573,10 @@ async fn admin_update_package(
             credits = COALESCE($3, credits),
             price_inr = COALESCE($4, price_inr),
             is_active = COALESCE($5, is_active),
+            applicable_roles = COALESCE($6, applicable_roles),
             updated_at = NOW()
-        WHERE id = $6
-        RETURNING id, name, description, credits, price_inr, is_active, created_at, updated_at
+        WHERE id = $7
+        RETURNING id, name, description, credits, price_inr, is_active, applicable_roles, created_at, updated_at
         "#,
     )
     .bind(&body.name)
@@ -534,6 +584,7 @@ async fn admin_update_package(
     .bind(body.credits)
     .bind(body.price_inr)
     .bind(body.is_active)
+    .bind(&body.applicable_roles)
     .bind(id)
     .fetch_optional(&state.pool)
     .await

crates/db/migrations/20260814010000_ai_credit_packages_role_scoping.down.sql

@@ -0,0 +1,6 @@
+BEGIN;
+
+DROP INDEX IF EXISTS idx_ai_credit_packages_applicable_roles;
+ALTER TABLE ai_credit_packages DROP COLUMN IF EXISTS applicable_roles;
+
+COMMIT;

crates/db/migrations/20260814010000_ai_credit_packages_role_scoping.up.sql

@@ -0,0 +1,17 @@
+-- Role-scoped AI credit packages, mirroring pricing_packages' existing
+-- role_key convention (though as an array here since one AI package can
+-- reasonably apply to several roles at once, unlike TraceCoin packages
+-- which are one row per role). Empty array = visible/purchasable by every
+-- role (the default, matching today's actual behavior for the 4 existing
+-- packages so nothing changes for them until an admin opts them into
+-- specific roles).
+
+BEGIN;
+
+ALTER TABLE ai_credit_packages
+    ADD COLUMN IF NOT EXISTS applicable_roles TEXT[] NOT NULL DEFAULT '{}';
+
+CREATE INDEX IF NOT EXISTS idx_ai_credit_packages_applicable_roles
+    ON ai_credit_packages USING GIN (applicable_roles);
+
+COMMIT;