diff --git a/packages/api/openapi/components/schemas.yaml b/packages/api/openapi/components/schemas.yaml
index bd6be25..98c2009 100644
--- a/packages/api/openapi/components/schemas.yaml
+++ b/packages/api/openapi/components/schemas.yaml
@@ -352,3 +352,135 @@ Document:
     downloadUrl:
       type: string
       description: Presigned GET URL returned on confirm or get.
+ApprovalPolicy:
+  type: object
+  required: [id, name, priority, active, createdAt, updatedAt]
+  properties:
+    id:
+      type: string
+      format: uuid
+      description: Policy primary key.
+      example: cccccccc-cccc-4ccc-8ccc-cccccccccccc
+    name:
+      type: string
+      description: Policy display name.
+      example: Default approver policy
+    priority:
+      type: integer
+      description: Lower numbers match first.
+      example: 10
+    amountThreshold:
+      type: [string, "null"]
+      description: Minimum invoice amount that matches this policy.
+      example: "0.00"
+    skipBelowAmount:
+      type: [string, "null"]
+      description: Amounts below this skip the approval step.
+      example: "25.00"
+    active:
+      type: boolean
+      description: Whether the policy is considered when matching.
+      example: true
+    createdAt:
+      type: string
+      format: date-time
+      description: Row creation time.
+    updatedAt:
+      type: string
+      format: date-time
+      description: Row update time.
+ApprovalStep:
+  type: object
+  required: [id, invoiceId, stepOrder, approverRole, status, createdAt]
+  properties:
+    id:
+      type: string
+      format: uuid
+      description: Step primary key.
+      example: eeeeeeee-eeee-4eee-8eee-eeeeeeeeeeee
+    invoiceId:
+      type: string
+      format: uuid
+      description: Parent invoice id.
+    policyId:
+      type: [string, "null"]
+      format: uuid
+      description: Policy that created the step.
+    stepOrder:
+      type: integer
+      description: Order within the invoice.
+      example: 1
+    approverRole:
+      type: string
+      enum: [admin, ap_processor, approver, viewer]
+      description: Role allowed to act when no assignee is set.
+      example: approver
+    assigneeUserId:
+      type: [string, "null"]
+      format: uuid
+      description: Optional assigned user.
+    status:
+      type: string
+      enum: [pending, approved, rejected, skipped]
+      description: Step status.
+      example: pending
+    actedByUserId:
+      type: [string, "null"]
+      format: uuid
+      description: User who acted.
+    actedAt:
+      type: [string, "null"]
+      format: date-time
+      description: When the step was acted on.
+    createdAt:
+      type: string
+      format: date-time
+      description: Row creation time.
+InvoiceComment:
+  type: object
+  required: [id, invoiceId, body, createdAt]
+  properties:
+    id:
+      type: string
+      format: uuid
+      description: Comment primary key.
+    invoiceId:
+      type: string
+      format: uuid
+      description: Parent invoice id.
+    authorUserId:
+      type: [string, "null"]
+      format: uuid
+      description: Author user id.
+    body:
+      type: string
+      description: Comment text.
+      example: Looks good.
+    createdAt:
+      type: string
+      format: date-time
+      description: Row creation time.
+ActivityLog:
+  type: object
+  required: [id, invoiceId, message, createdAt]
+  properties:
+    id:
+      type: string
+      format: uuid
+      description: Activity row primary key.
+    invoiceId:
+      type: string
+      format: uuid
+      description: Parent invoice id.
+    actorUserId:
+      type: [string, "null"]
+      format: uuid
+      description: Actor user id.
+    message:
+      type: string
+      description: Activity message.
+      example: Step approved.
+    createdAt:
+      type: string
+      format: date-time
+      description: Row creation time.
diff --git a/packages/api/openapi/openapi.yaml b/packages/api/openapi/openapi.yaml
index f0881a3..4e9d19d 100644
--- a/packages/api/openapi/openapi.yaml
+++ b/packages/api/openapi/openapi.yaml
@@ -19,6 +19,8 @@ tags:
     description: Invoice headers, coding lines, and uniqueness rules.
   - name: Documents
     description: Presigned document upload, confirm, and download against MinIO or S3.
+  - name: Approvals
+    description: Approval policies, step decisions, inbox, comments, and activity.
 paths:
   /api/health:
     $ref: ./paths/health.yaml
@@ -62,6 +64,18 @@ paths:
     $ref: ./paths/documents-id.yaml
   /api/documents/{id}/confirmations:
     $ref: ./paths/documents-id-confirmations.yaml
+  /api/approval-policies:
+    $ref: ./paths/approval-policies.yaml
+  /api/approval-policies/{id}:
+    $ref: ./paths/approval-policies-id.yaml
+  /api/approval-steps/{id}/decisions:
+    $ref: ./paths/approval-steps-id-decisions.yaml
+  /api/inbox:
+    $ref: ./paths/inbox.yaml
+  /api/invoices/{id}/comments:
+    $ref: ./paths/invoices-id-comments.yaml
+  /api/invoices/{id}/activity-logs:
+    $ref: ./paths/invoices-id-activity-logs.yaml
 components:
   securitySchemes:
     cookieAuth:
@@ -89,5 +103,13 @@ components:
       $ref: ./components/schemas.yaml#/InvoiceLine
     Document:
       $ref: ./components/schemas.yaml#/Document
+    ApprovalPolicy:
+      $ref: ./components/schemas.yaml#/ApprovalPolicy
+    ApprovalStep:
+      $ref: ./components/schemas.yaml#/ApprovalStep
+    InvoiceComment:
+      $ref: ./components/schemas.yaml#/InvoiceComment
+    ActivityLog:
+      $ref: ./components/schemas.yaml#/ActivityLog
 security:
   - cookieAuth: []
diff --git a/packages/api/openapi/paths/approval-policies-id.yaml b/packages/api/openapi/paths/approval-policies-id.yaml
new file mode 100644
index 0000000..e0378f8
--- /dev/null
+++ b/packages/api/openapi/paths/approval-policies-id.yaml
@@ -0,0 +1,91 @@
+parameters:
+  - name: id
+    in: path
+    required: true
+    description: Policy primary key.
+    schema:
+      type: string
+      format: uuid
+    example: cccccccc-cccc-4ccc-8ccc-cccccccccccc
+get:
+  tags: [Approvals]
+  summary: Get an approval policy
+  description: Returns one approval policy by id.
+  operationId: get-api-approval-policies-id
+  responses:
+    "200":
+      description: Policy.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/ApprovalPolicy
+    "400":
+      description: Invalid id.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
+    "401":
+      description: Missing session.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
+    "404":
+      description: Policy not found.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
+patch:
+  tags: [Approvals]
+  summary: Update an approval policy
+  description: Admin-only patch. Requires admin:settings.
+  operationId: patch-api-approval-policies-id
+  requestBody:
+    required: true
+    content:
+      application/json:
+        schema:
+          type: object
+          properties:
+            name:
+              type: string
+              example: Default approver policy
+            priority:
+              type: integer
+              example: 10
+            amountThreshold:
+              type: string
+              example: "0.00"
+            skipBelowAmount:
+              type: string
+              example: "25.00"
+            active:
+              type: boolean
+              example: true
+  responses:
+    "200":
+      description: Updated policy.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/ApprovalPolicy
+    "400":
+      description: Validation failed.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
+    "403":
+      description: Caller lacks admin:settings.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
+    "404":
+      description: Policy not found.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
diff --git a/packages/api/openapi/paths/approval-policies.yaml b/packages/api/openapi/paths/approval-policies.yaml
new file mode 100644
index 0000000..bac3711
--- /dev/null
+++ b/packages/api/openapi/paths/approval-policies.yaml
@@ -0,0 +1,71 @@
+get:
+  tags: [Approvals]
+  summary: List approval policies
+  description: Returns every approval policy.
+  operationId: get-api-approval-policies
+  responses:
+    "200":
+      description: Policy list.
+      content:
+        application/json:
+          schema:
+            type: object
+            required: [items]
+            properties:
+              items:
+                type: array
+                items:
+                  $ref: ../components/schemas.yaml#/ApprovalPolicy
+    "401":
+      description: Missing session.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
+post:
+  tags: [Approvals]
+  summary: Create an approval policy
+  description: Admin-only insert. Requires admin:settings.
+  operationId: post-api-approval-policies
+  requestBody:
+    required: true
+    content:
+      application/json:
+        schema:
+          type: object
+          required: [name]
+          properties:
+            name:
+              type: string
+              example: High dollar
+            priority:
+              type: integer
+              example: 1
+            amountThreshold:
+              type: string
+              example: "500.00"
+            skipBelowAmount:
+              type: string
+              example: "25.00"
+            active:
+              type: boolean
+              example: true
+  responses:
+    "201":
+      description: Created policy.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/ApprovalPolicy
+    "400":
+      description: Validation failed.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
+    "403":
+      description: Caller lacks admin:settings.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
diff --git a/packages/api/openapi/paths/approval-steps-id-decisions.yaml b/packages/api/openapi/paths/approval-steps-id-decisions.yaml
new file mode 100644
index 0000000..457a467
--- /dev/null
+++ b/packages/api/openapi/paths/approval-steps-id-decisions.yaml
@@ -0,0 +1,57 @@
+parameters:
+  - name: id
+    in: path
+    required: true
+    description: Approval step primary key.
+    schema:
+      type: string
+      format: uuid
+    example: eeeeeeee-eeee-4eee-8eee-eeeeeeeeeeee
+post:
+  tags: [Approvals]
+  summary: Record an approval decision
+  description: Approves, rejects, or skips a pending step. Requires approve:invoices.
+  operationId: post-api-approval-steps-id-decisions
+  requestBody:
+    required: true
+    content:
+      application/json:
+        schema:
+          type: object
+          required: [action]
+          properties:
+            action:
+              type: string
+              enum: [approve, reject, skip]
+              example: approve
+  responses:
+    "200":
+      description: Updated step.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/ApprovalStep
+    "400":
+      description: Validation failed.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
+    "403":
+      description: Caller lacks approve:invoices.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
+    "404":
+      description: Step not found.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
+    "409":
+      description: Step is not pending.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
diff --git a/packages/api/openapi/paths/inbox.yaml b/packages/api/openapi/paths/inbox.yaml
new file mode 100644
index 0000000..b6ae046
--- /dev/null
+++ b/packages/api/openapi/paths/inbox.yaml
@@ -0,0 +1,24 @@
+get:
+  tags: [Approvals]
+  summary: List the caller approval inbox
+  description: Returns pending steps visible to the caller.
+  operationId: get-api-inbox
+  responses:
+    "200":
+      description: Inbox items.
+      content:
+        application/json:
+          schema:
+            type: object
+            required: [items]
+            properties:
+              items:
+                type: array
+                items:
+                  $ref: ../components/schemas.yaml#/ApprovalStep
+    "401":
+      description: Missing session.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
diff --git a/packages/api/openapi/paths/invoices-id-activity-logs.yaml b/packages/api/openapi/paths/invoices-id-activity-logs.yaml
new file mode 100644
index 0000000..6ddd237
--- /dev/null
+++ b/packages/api/openapi/paths/invoices-id-activity-logs.yaml
@@ -0,0 +1,45 @@
+parameters:
+  - name: id
+    in: path
+    required: true
+    description: Invoice primary key.
+    schema:
+      type: string
+      format: uuid
+    example: 88888888-8888-4888-8888-888888888888
+get:
+  tags: [Approvals]
+  summary: List invoice activity
+  description: Returns activity log rows for one invoice.
+  operationId: get-api-invoices-id-activity-logs
+  responses:
+    "200":
+      description: Activity list.
+      content:
+        application/json:
+          schema:
+            type: object
+            required: [items]
+            properties:
+              items:
+                type: array
+                items:
+                  $ref: ../components/schemas.yaml#/ActivityLog
+    "400":
+      description: Invalid id.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
+    "401":
+      description: Missing session.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
+    "404":
+      description: Invoice not found.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
diff --git a/packages/api/openapi/paths/invoices-id-comments.yaml b/packages/api/openapi/paths/invoices-id-comments.yaml
new file mode 100644
index 0000000..e8d4a36
--- /dev/null
+++ b/packages/api/openapi/paths/invoices-id-comments.yaml
@@ -0,0 +1,80 @@
+parameters:
+  - name: id
+    in: path
+    required: true
+    description: Invoice primary key.
+    schema:
+      type: string
+      format: uuid
+    example: 88888888-8888-4888-8888-888888888888
+get:
+  tags: [Approvals]
+  summary: List invoice comments
+  description: Returns comments on one invoice.
+  operationId: get-api-invoices-id-comments
+  responses:
+    "200":
+      description: Comment list.
+      content:
+        application/json:
+          schema:
+            type: object
+            required: [items]
+            properties:
+              items:
+                type: array
+                items:
+                  $ref: ../components/schemas.yaml#/InvoiceComment
+    "400":
+      description: Invalid id.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
+    "401":
+      description: Missing session.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
+    "404":
+      description: Invoice not found.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
+post:
+  tags: [Approvals]
+  summary: Add an invoice comment
+  description: Appends a comment and an activity row.
+  operationId: post-api-invoices-id-comments
+  requestBody:
+    required: true
+    content:
+      application/json:
+        schema:
+          type: object
+          required: [body]
+          properties:
+            body:
+              type: string
+              example: Looks good.
+  responses:
+    "201":
+      description: Created comment.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/InvoiceComment
+    "400":
+      description: Validation failed.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
+    "404":
+      description: Invoice not found.
+      content:
+        application/json:
+          schema:
+            $ref: ../components/schemas.yaml#/Error
diff --git a/packages/api/src/app.ts b/packages/api/src/app.ts
index 455b8f5..eb647df 100644
--- a/packages/api/src/app.ts
+++ b/packages/api/src/app.ts
@@ -10,6 +10,7 @@ import { createGlAccountRoutes } from "./routes/gl-accounts.js";
 import { createDepartmentRoutes } from "./routes/departments.js";
 import { createUserRoutes } from "./routes/users.js";
 import { createInvoiceRoutes } from "./routes/invoices.js";
+import { createApprovalRoutes } from "./routes/approvals.js";
 import { createDocumentsStore, type DocumentsStore } from "./documents.js";
 import { errorJson } from "./http.js";
 import { cloudFrontOriginAllowed } from "./auth/origin-verify.js";
@@ -52,6 +53,7 @@ export function createApp(env: ApiEnv, handle: Db, deps: AppDeps = {}) {
   api.route("/", createDepartmentRoutes(handle));
   api.route("/", createUserRoutes(handle));
   api.route("/", createInvoiceRoutes(handle, deps.documents ?? createDocumentsStore(env)));
+  api.route("/", createApprovalRoutes(handle));
   app.route("/api", api);
 
   app.notFound((c) => errorJson(c, 404, "NOT_FOUND", "Not found."));
diff --git a/packages/api/src/approvals.ts b/packages/api/src/approvals.ts
new file mode 100644
index 0000000..509b94d
--- /dev/null
+++ b/packages/api/src/approvals.ts
@@ -0,0 +1,74 @@
+import { eq } from "drizzle-orm";
+import type { Db } from "./db/client.js";
+import { activityLog, approvalPolicies, approvalSteps, invoices } from "./db/schema/index.js";
+import { moneyCents, rowsOf } from "./routes/helpers.js";
+
+type InvoiceRow = typeof invoices.$inferSelect;
+type PolicyRow = typeof approvalPolicies.$inferSelect;
+type StepRow = typeof approvalSteps.$inferSelect;
+
+export async function appendActivity(
+  handle: Db,
+  invoiceId: string,
+  actorUserId: string,
+  message: string,
+) {
+  await handle.db.insert(activityLog).values({ invoiceId, actorUserId, message }).returning();
+}
+
+export async function applyMatchingPolicy(
+  handle: Db,
+  invoice: InvoiceRow,
+  actorUserId: string,
+): Promise<InvoiceRow> {
+  await appendActivity(handle, invoice.id, actorUserId, "Invoice created.");
+  const policies = (await rowsOf<PolicyRow>(handle, approvalPolicies))
+    .filter((policy) => policy.active)
+    .sort((a, b) => a.priority - b.priority);
+  const amount = moneyCents(invoice.amount);
+  const matched = policies.find((policy) => {
+    if (policy.amountThreshold == null) return true;
+    return amount >= moneyCents(policy.amountThreshold);
+  });
+  if (!matched) return invoice;
+
+  const skip = matched.skipBelowAmount != null && amount < moneyCents(matched.skipBelowAmount);
+  await handle.db
+    .insert(approvalSteps)
+    .values({
+      invoiceId: invoice.id,
+      policyId: matched.id,
+      stepOrder: 1,
+      approverRole: "approver",
+      status: skip ? "skipped" : "pending",
+      actedByUserId: skip ? actorUserId : null,
+      actedAt: skip ? new Date() : null,
+    })
+    .returning();
+  if (!skip) {
+    await appendActivity(
+      handle,
+      invoice.id,
+      actorUserId,
+      `Approval required by policy ${matched.name}.`,
+    );
+    return invoice;
+  }
+  await appendActivity(
+    handle,
+    invoice.id,
+    actorUserId,
+    `Step skipped because amount is below ${matched.skipBelowAmount}.`,
+  );
+  const [updated] = await handle.db
+    .update(invoices)
+    .set({ id: invoice.id, status: "approved", updatedAt: new Date() })
+    .where(eq(invoices.id, invoice.id))
+    .returning();
+  return updated ?? { ...invoice, status: "approved" };
+}
+
+export async function remainingPending(handle: Db, invoiceId: string): Promise<StepRow[]> {
+  const rows = await rowsOf<StepRow>(handle, approvalSteps);
+  return rows.filter((row) => row.invoiceId === invoiceId && row.status === "pending");
+}
diff --git a/packages/api/src/routes/approvals.test.ts b/packages/api/src/routes/approvals.test.ts
new file mode 100644
index 0000000..4a50cc3
--- /dev/null
+++ b/packages/api/src/routes/approvals.test.ts
@@ -0,0 +1,110 @@
+import { describe, expect, it } from "vitest";
+import { createApp } from "../app.js";
+import { createMemoryDocumentsStore } from "../documents.js";
+import { loadEnv } from "../env.js";
+import type { ErrorEnvelope } from "../http.js";
+import { createFakeDb, SEED } from "../test/fake-db.js";
+
+function expectEnvelope(body: unknown, code: string) {
+  const envelope = body as ErrorEnvelope;
+  expect(envelope.error.code).toBe(code);
+}
+
+function envFor(role: "admin" | "approver" | "viewer") {
+  return loadEnv({
+    NODE_ENV: "test",
+    DEV_AUTH_BYPASS: "true",
+    DEV_AUTH_SUB: SEED.user.cognitoSub,
+    DEV_AUTH_EMAIL: SEED.user.email,
+    DEV_AUTH_NAME: SEED.user.name,
+    DEV_AUTH_ROLE: role,
+  });
+}
+
+const jsonHeaders = {
+  "content-type": "application/json",
+  origin: "http://127.0.0.1:3000",
+};
+
+function app(role: "admin" | "approver" | "viewer" = "admin") {
+  return createApp(envFor(role), createFakeDb(), { documents: createMemoryDocumentsStore() });
+}
+
+describe("approval stubs", () => {
+  it("skips a step when the invoice is below skipBelowAmount", async () => {
+    const api = app();
+    const response = await api.request("/api/invoices", {
+      method: "POST",
+      headers: jsonHeaders,
+      body: JSON.stringify({
+        vendorId: SEED.vendor.id,
+        invoiceNumber: "INV-SKIP",
+        amount: "10.00",
+        dueDate: "2026-10-01",
+      }),
+    });
+    expect(response.status).toBe(201);
+    const invoice = (await response.json()) as { id: string; status: string };
+    expect(invoice.status).toBe("approved");
+    const activity = await api.request(`/api/invoices/${invoice.id}/activity-logs`);
+    expect(activity.status).toBe(200);
+    const log = (await activity.json()) as { items: Array<{ message: string }> };
+    expect(log.items.some((item) => item.message.includes("below"))).toBe(true);
+  });
+
+  it("approves a pending step and writes activity", async () => {
+    const api = app("approver");
+    const response = await api.request(`/api/approval-steps/${SEED.step.id}/decisions`, {
+      method: "POST",
+      headers: jsonHeaders,
+      body: JSON.stringify({ action: "approve" }),
+    });
+    expect(response.status).toBe(200);
+    await expect(response.json()).resolves.toMatchObject({ status: "approved" });
+    const activity = await api.request(`/api/invoices/${SEED.invoice.id}/activity-logs`);
+    const log = (await activity.json()) as { items: Array<{ message: string }> };
+    expect(log.items.some((item) => item.message === "Step approved.")).toBe(true);
+  });
+
+  it("returns 403 when a viewer acts on a step", async () => {
+    const api = app("viewer");
+    const response = await api.request(`/api/approval-steps/${SEED.step.id}/decisions`, {
+      method: "POST",
+      headers: jsonHeaders,
+      body: JSON.stringify({ action: "approve" }),
+    });
+    expect(response.status).toBe(403);
+    expectEnvelope(await response.json(), "FORBIDDEN");
+  });
+
+  it("lists the caller inbox and accepts a comment", async () => {
+    const api = app("admin");
+    const inbox = await api.request("/api/inbox");
+    expect(inbox.status).toBe(200);
+    const listed = (await inbox.json()) as { items: Array<{ id: string }> };
+    expect(listed.items[0]?.id).toBe(SEED.step.id);
+    const comment = await api.request(`/api/invoices/${SEED.invoice.id}/comments`, {
+      method: "POST",
+      headers: jsonHeaders,
+      body: JSON.stringify({ body: "Looks good." }),
+    });
+    expect(comment.status).toBe(201);
+    await expect(comment.json()).resolves.toMatchObject({ body: "Looks good." });
+  });
+
+  it("creates an approval policy as admin", async () => {
+    const api = app("admin");
+    const response = await api.request("/api/approval-policies", {
+      method: "POST",
+      headers: jsonHeaders,
+      body: JSON.stringify({
+        name: "High dollar",
+        priority: 1,
+        amountThreshold: "500.00",
+        skipBelowAmount: "0.00",
+      }),
+    });
+    expect(response.status).toBe(201);
+    await expect(response.json()).resolves.toMatchObject({ name: "High dollar", priority: 1 });
+  });
+});
diff --git a/packages/api/src/routes/approvals.ts b/packages/api/src/routes/approvals.ts
new file mode 100644
index 0000000..c7f55e3
--- /dev/null
+++ b/packages/api/src/routes/approvals.ts
@@ -0,0 +1,285 @@
+import { eq } from "drizzle-orm";
+import { Hono } from "hono";
+import type { Db } from "../db/client.js";
+import {
+  activityLog,
+  approvalPolicies,
+  approvalSteps,
+  invoiceComments,
+  invoices,
+} from "../db/schema/index.js";
+import type { AppBindings } from "../auth/middleware.js";
+import { errorJson } from "../http.js";
+import {
+  asMoney,
+  asString,
+  caller,
+  firstById,
+  iso,
+  isUuid,
+  parseJsonBody,
+  requireCan,
+  rowsOf,
+} from "./helpers.js";
+import { appendActivity, remainingPending } from "../approvals.js";
+import type { UserRole } from "../env.js";
+
+type PolicyRow = typeof approvalPolicies.$inferSelect;
+type StepRow = typeof approvalSteps.$inferSelect;
+type InvoiceRow = typeof invoices.$inferSelect;
+type CommentRow = typeof invoiceComments.$inferSelect;
+type ActivityRow = typeof activityLog.$inferSelect;
+
+const DECISIONS = ["approve", "reject", "skip"] as const;
+type Decision = (typeof DECISIONS)[number];
+
+function isDecision(value: string): value is Decision {
+  return (DECISIONS as readonly string[]).includes(value);
+}
+
+function toPolicy(row: PolicyRow) {
+  return {
+    id: row.id,
+    name: row.name,
+    priority: row.priority,
+    amountThreshold: row.amountThreshold,
+    skipBelowAmount: row.skipBelowAmount,
+    active: row.active,
+    createdAt: iso(row.createdAt),
+    updatedAt: iso(row.updatedAt),
+  };
+}
+
+function toStep(row: StepRow) {
+  return {
+    id: row.id,
+    invoiceId: row.invoiceId,
+    policyId: row.policyId,
+    stepOrder: row.stepOrder,
+    approverRole: row.approverRole,
+    assigneeUserId: row.assigneeUserId,
+    status: row.status,
+    actedByUserId: row.actedByUserId,
+    actedAt: row.actedAt ? iso(row.actedAt) : null,
+    createdAt: iso(row.createdAt),
+  };
+}
+
+function inboxVisible(step: StepRow, user: { id: string; role: UserRole }): boolean {
+  if (step.status !== "pending") return false;
+  if (step.assigneeUserId) return step.assigneeUserId === user.id;
+  return user.role === "admin" || user.role === step.approverRole;
+}
+
+export function createApprovalRoutes(handle: Db) {
+  const routes = new Hono<AppBindings>();
+
+  routes.get("/approval-policies", async (c) => {
+    const denied = requireCan(c, "read:invoices");
+    if (denied) return denied;
+    const rows = await rowsOf<PolicyRow>(handle, approvalPolicies);
+    return c.json({ items: rows.map(toPolicy) });
+  });
+
+  routes.post("/approval-policies", async (c) => {
+    const denied = requireCan(c, "admin:settings");
+    if (denied) return denied;
+    const body = await parseJsonBody(c);
+    const name = asString(body.name).trim();
+    if (!name) return errorJson(c, 400, "VALIDATION_ERROR", "Name is required.");
+    const [row] = await handle.db
+      .insert(approvalPolicies)
+      .values({
+        name,
+        priority: typeof body.priority === "number" ? body.priority : 100,
+        amountThreshold: asMoney(body.amountThreshold),
+        skipBelowAmount: asMoney(body.skipBelowAmount),
+        active: body.active === false ? false : true,
+      })
+      .returning();
+    return c.json(toPolicy(row), 201);
+  });
+
+  routes.get("/approval-policies/:id", async (c) => {
+    const denied = requireCan(c, "read:invoices");
+    if (denied) return denied;
+    const id = c.req.param("id");
+    if (!isUuid(id)) return errorJson(c, 400, "VALIDATION_ERROR", "Invalid policy id.");
+    const row = await firstById<PolicyRow>(handle, approvalPolicies, id);
+    if (!row) return errorJson(c, 404, "NOT_FOUND", "Policy not found.");
+    return c.json(toPolicy(row));
+  });
+
+  routes.patch("/approval-policies/:id", async (c) => {
+    const denied = requireCan(c, "admin:settings");
+    if (denied) return denied;
+    const id = c.req.param("id");
+    if (!isUuid(id)) return errorJson(c, 400, "VALIDATION_ERROR", "Invalid policy id.");
+    const existing = await firstById<PolicyRow>(handle, approvalPolicies, id);
+    if (!existing) return errorJson(c, 404, "NOT_FOUND", "Policy not found.");
+    const body = await parseJsonBody(c);
+    const patch: Partial<typeof approvalPolicies.$inferInsert> & { id: string } = {
+      id,
+      updatedAt: new Date(),
+    };
+    if (body.name !== undefined) {
+      const name = asString(body.name).trim();
+      if (!name) return errorJson(c, 400, "VALIDATION_ERROR", "Name is required.");
+      patch.name = name;
+    }
+    if (typeof body.priority === "number") patch.priority = body.priority;
+    if (body.amountThreshold !== undefined) patch.amountThreshold = asMoney(body.amountThreshold);
+    if (body.skipBelowAmount !== undefined) patch.skipBelowAmount = asMoney(body.skipBelowAmount);
+    if (typeof body.active === "boolean") patch.active = body.active;
+    const [row] = await handle.db
+      .update(approvalPolicies)
+      .set(patch)
+      .where(eq(approvalPolicies.id, id))
+      .returning();
+    return c.json(toPolicy(row));
+  });
+
+  routes.get("/inbox", async (c) => {
+    const denied = requireCan(c, "read:invoices");
+    if (denied) return denied;
+    const user = caller(c);
+    const steps = await rowsOf<StepRow>(handle, approvalSteps);
+    const invoiceRows = await rowsOf<InvoiceRow>(handle, invoices);
+    const items = steps
+      .filter((step) => inboxVisible(step, user))
+      .map((step) => {
+        const invoice = invoiceRows.find((row) => row.id === step.invoiceId);
+        return {
+          ...toStep(step),
+          invoiceNumber: invoice?.invoiceNumber ?? null,
+          amount: invoice?.amount ?? null,
+          vendorId: invoice?.vendorId ?? null,
+        };
+      });
+    return c.json({ items });
+  });
+
+  routes.post("/approval-steps/:id/decisions", async (c) => {
+    const denied = requireCan(c, "approve:invoices");
+    if (denied) return denied;
+    const id = c.req.param("id");
+    if (!isUuid(id)) return errorJson(c, 400, "VALIDATION_ERROR", "Invalid step id.");
+    const step = await firstById<StepRow>(handle, approvalSteps, id);
+    if (!step) return errorJson(c, 404, "NOT_FOUND", "Approval step not found.");
+    if (step.status !== "pending") {
+      return errorJson(c, 409, "CONFLICT", "Step is not pending.");
+    }
+    const body = await parseJsonBody(c);
+    const action = asString(body.action);
+    if (!isDecision(action)) {
+      return errorJson(c, 400, "VALIDATION_ERROR", "action must be approve, reject, or skip.");
+    }
+    const user = caller(c);
+    const nextStatus =
+      action === "approve" ? "approved" : action === "reject" ? "rejected" : "skipped";
+    const [updated] = await handle.db
+      .update(approvalSteps)
+      .set({
+        id,
+        status: nextStatus,
+        actedByUserId: user.id,
+        actedAt: new Date(),
+      })
+      .where(eq(approvalSteps.id, id))
+      .returning();
+    await appendActivity(
+      handle,
+      step.invoiceId,
+      user.id,
+      action === "approve"
+        ? "Step approved."
+        : action === "reject"
+          ? "Step rejected."
+          : "Step skipped.",
+    );
+    let invoiceStatus: InvoiceRow["status"] | undefined;
+    if (action === "reject") invoiceStatus = "rejected";
+    else if ((await remainingPending(handle, step.invoiceId)).length === 0) {
+      invoiceStatus = "approved";
+    }
+    if (invoiceStatus) {
+      await handle.db
+        .update(invoices)
+        .set({ id: step.invoiceId, status: invoiceStatus, updatedAt: new Date() })
+        .where(eq(invoices.id, step.invoiceId))
+        .returning();
+    }
+    return c.json(toStep(updated));
+  });
+
+  routes.get("/invoices/:id/comments", async (c) => {
+    const denied = requireCan(c, "read:invoices");
+    if (denied) return denied;
+    const id = c.req.param("id");
+    if (!isUuid(id)) return errorJson(c, 400, "VALIDATION_ERROR", "Invalid invoice id.");
+    const invoice = await firstById<InvoiceRow>(handle, invoices, id);
+    if (!invoice) return errorJson(c, 404, "NOT_FOUND", "Invoice not found.");
+    const rows = (await rowsOf<CommentRow>(handle, invoiceComments)).filter(
+      (row) => row.invoiceId === id,
+    );
+    return c.json({
+      items: rows.map((row) => ({
+        id: row.id,
+        invoiceId: row.invoiceId,
+        authorUserId: row.authorUserId,
+        body: row.body,
+        createdAt: iso(row.createdAt),
+      })),
+    });
+  });
+
+  routes.post("/invoices/:id/comments", async (c) => {
+    const denied = requireCan(c, "read:invoices");
+    if (denied) return denied;
+    const id = c.req.param("id");
+    if (!isUuid(id)) return errorJson(c, 400, "VALIDATION_ERROR", "Invalid invoice id.");
+    const invoice = await firstById<InvoiceRow>(handle, invoices, id);
+    if (!invoice) return errorJson(c, 404, "NOT_FOUND", "Invoice not found.");
+    const body = asString((await parseJsonBody(c)).body).trim();
+    if (!body) return errorJson(c, 400, "VALIDATION_ERROR", "body is required.");
+    const user = caller(c);
+    const [row] = await handle.db
+      .insert(invoiceComments)
+      .values({ invoiceId: id, authorUserId: user.id, body })
+      .returning();
+    await appendActivity(handle, id, user.id, "Comment added.");
+    return c.json(
+      {
+        id: row.id,
+        invoiceId: row.invoiceId,
+        authorUserId: row.authorUserId,
+        body: row.body,
+        createdAt: iso(row.createdAt),
+      },
+      201,
+    );
+  });
+
+  routes.get("/invoices/:id/activity-logs", async (c) => {
+    const denied = requireCan(c, "read:invoices");
+    if (denied) return denied;
+    const id = c.req.param("id");
+    if (!isUuid(id)) return errorJson(c, 400, "VALIDATION_ERROR", "Invalid invoice id.");
+    const invoice = await firstById<InvoiceRow>(handle, invoices, id);
+    if (!invoice) return errorJson(c, 404, "NOT_FOUND", "Invoice not found.");
+    const rows = (await rowsOf<ActivityRow>(handle, activityLog)).filter(
+      (row) => row.invoiceId === id,
+    );
+    return c.json({
+      items: rows.map((row) => ({
+        id: row.id,
+        invoiceId: row.invoiceId,
+        actorUserId: row.actorUserId,
+        message: row.message,
+        createdAt: iso(row.createdAt),
+      })),
+    });
+  });
+
+  return routes;
+}
diff --git a/packages/api/src/routes/invoices.ts b/packages/api/src/routes/invoices.ts
index 87bf05b..1528ed9 100644
--- a/packages/api/src/routes/invoices.ts
+++ b/packages/api/src/routes/invoices.ts
@@ -5,6 +5,7 @@ import type { DocumentsStore } from "../documents.js";
 import { documents, invoiceLines, invoices, vendors } from "../db/schema/index.js";
 import type { AppBindings } from "../auth/middleware.js";
 import { errorJson } from "../http.js";
+import { applyMatchingPolicy } from "../approvals.js";
 import {
   asMoney,
   asString,
@@ -246,7 +247,8 @@ export function createInvoiceRoutes(handle: Db, store: DocumentsStore) {
         .values({ invoiceId: row.id, ...line })
         .returning();
     }
-    return c.json(toInvoice(row, await linesFor(handle, row.id)), 201);
+    const latest = await applyMatchingPolicy(handle, row, caller(c).id);
+    return c.json(toInvoice(latest, await linesFor(handle, row.id)), 201);
   });
 
   routes.patch("/invoices/:id", async (c) => {
@@ -257,7 +259,7 @@ export function createInvoiceRoutes(handle: Db, store: DocumentsStore) {
     const existing = await firstById<InvoiceRow>(handle, invoices, id);
     if (!existing) return errorJson(c, 404, "NOT_FOUND", "Invoice not found.");
     const body = await parseJsonBody(c);
-    const patch: Partial<typeof invoices.$inferInsert> = { updatedAt: new Date() };
+    const patch: Partial<typeof invoices.$inferInsert> = { id, updatedAt: new Date() };
     if (body.vendorId !== undefined) {
       const vendorId = asString(body.vendorId);
       if (!isUuid(vendorId)) return errorJson(c, 400, "VALIDATION_ERROR", "Invalid vendorId.");
diff --git a/packages/api/src/test/fake-db.ts b/packages/api/src/test/fake-db.ts
index b9d10f4..d18380f 100644
--- a/packages/api/src/test/fake-db.ts
+++ b/packages/api/src/test/fake-db.ts
@@ -68,6 +68,42 @@ export const SEED = {
     uploadedByUserId: "11111111-1111-4111-8111-111111111111",
     createdAt: new Date("2026-01-01T00:00:00.000Z"),
   },
+  policy: {
+    id: "cccccccc-cccc-4ccc-8ccc-cccccccccccc",
+    name: "Default approver policy",
+    priority: 10,
+    amountThreshold: "0.00",
+    skipBelowAmount: "25.00",
+    active: true,
+    createdAt: new Date("2026-01-01T00:00:00.000Z"),
+    updatedAt: new Date("2026-01-01T00:00:00.000Z"),
+  },
+  step: {
+    id: "eeeeeeee-eeee-4eee-8eee-eeeeeeeeeeee",
+    invoiceId: "88888888-8888-4888-8888-888888888888",
+    policyId: "cccccccc-cccc-4ccc-8ccc-cccccccccccc",
+    stepOrder: 1,
+    approverRole: "approver" as UserRole,
+    assigneeUserId: null as string | null,
+    status: "pending" as const,
+    actedByUserId: null as string | null,
+    actedAt: null as Date | null,
+    createdAt: new Date("2026-01-01T00:00:00.000Z"),
+  },
+  comment: {
+    id: "aaaaaaaa-aaaa-4aaa-8aaa-aaaaaaaaaaaa",
+    invoiceId: "88888888-8888-4888-8888-888888888888",
+    authorUserId: "11111111-1111-4111-8111-111111111111",
+    body: "Seed comment on INV-1001.",
+    createdAt: new Date("2026-01-01T00:00:00.000Z"),
+  },
+  activity: {
+    id: "bbbbbbbb-bbbb-4bbb-8bbb-bbbbbbbbbbbb",
+    invoiceId: "88888888-8888-4888-8888-888888888888",
+    actorUserId: "11111111-1111-4111-8111-111111111111",
+    message: "Invoice created from seed.",
+    createdAt: new Date("2026-01-01T00:00:00.000Z"),
+  },
 };
 
 export type Store = {
@@ -78,10 +114,10 @@ export type Store = {
   invoices: Array<typeof SEED.invoice>;
   invoiceLines: Array<typeof SEED.line>;
   documents: Array<typeof SEED.document>;
-  approvalPolicies: Array<Record<string, unknown>>;
-  approvalSteps: Array<Record<string, unknown>>;
-  invoiceComments: Array<Record<string, unknown>>;
-  activityLog: Array<Record<string, unknown>>;
+  approvalPolicies: Array<typeof SEED.policy>;
+  approvalSteps: Array<typeof SEED.step>;
+  invoiceComments: Array<typeof SEED.comment>;
+  activityLog: Array<typeof SEED.activity>;
 };
 
 export function emptyStore(): Store {
@@ -93,10 +129,10 @@ export function emptyStore(): Store {
     invoices: [{ ...SEED.invoice }],
     invoiceLines: [{ ...SEED.line }],
     documents: [{ ...SEED.document }],
-    approvalPolicies: [],
-    approvalSteps: [],
-    invoiceComments: [],
-    activityLog: [],
+    approvalPolicies: [{ ...SEED.policy }],
+    approvalSteps: [{ ...SEED.step }],
+    invoiceComments: [{ ...SEED.comment }],
+    activityLog: [{ ...SEED.activity }],
   };
 }
 
@@ -182,7 +218,8 @@ export function createFakeDb(store: Store = emptyStore()): Db {
         where: vi.fn(() => ({
           returning: vi.fn(async () => {
             const rows = rowsFor(store, table);
-            const current = rows[0];
+            const current =
+              (typeof patch.id === "string" && rows.find((row) => row.id === patch.id)) || rows[0];
             if (!current) return [];
             Object.assign(current, patch);
             return [current];
diff --git a/redocly.yaml b/redocly.yaml
index 6b39d1c..6b2c306 100644
--- a/redocly.yaml
+++ b/redocly.yaml
@@ -72,6 +72,7 @@ rules:
       - callback
       - refresh
       - logout
+      - inbox
   paths-kebab-case: error
   no-invalid-schema-examples: error
   # No schema-properties casing rule: property names mirror the DynamoDB
diff --git a/src/api/types.ts b/src/api/types.ts
index b4e3f46..e5b36b0 100644
--- a/src/api/types.ts
+++ b/src/api/types.ts
@@ -117,4 +117,7 @@ export type ApiPaths = {
   "/api/documents/{id}": {
     get: { response: Document };
   };
+  "/api/inbox": {
+    get: { response: { items: Array<{ id: string; invoiceId: string; status: string }> } };
+  };
 };