diff --git a/backend/src/cyclone/api.py b/backend/src/cyclone/api.py
index 16e33f5..2e09bdc 100644
--- a/backend/src/cyclone/api.py
+++ b/backend/src/cyclone/api.py
@@ -26,12 +26,13 @@ from datetime import datetime, timezone
 from contextlib import asynccontextmanager
 from typing import Any, AsyncIterator
 
-from fastapi import FastAPI, File, HTTPException, Query, Request, UploadFile
+from fastapi import Depends, FastAPI, File, HTTPException, Query, Request, UploadFile
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import JSONResponse, Response, StreamingResponse
 from pydantic import ValidationError
 
 from cyclone import __version__, db
+from cyclone.auth.deps import matrix_gate
 from cyclone.db import Claim, ClaimState, Remittance
 from cyclone.inbox_state import apply_999_rejections
 from cyclone.inbox_state_277ca import apply_277ca_rejections
@@ -255,7 +256,7 @@ def health() -> dict[str, str]:
     return {"status": "ok", "version": __version__}
 
 
-@app.post("/api/parse-837")
+@app.post("/api/parse-837", dependencies=[Depends(matrix_gate)])
 async def parse_837(
     request: Request,
     file: UploadFile = File(...),
@@ -448,7 +449,7 @@ def _reconciliation_summary_for_batch(batch_id: str) -> dict:
     }
 
 
-@app.post("/api/parse-835")
+@app.post("/api/parse-835", dependencies=[Depends(matrix_gate)])
 async def parse_835_endpoint(
     request: Request,
     file: UploadFile = File(...),
@@ -592,7 +593,7 @@ def _ack_synthetic_source_batch_id(interchange_control_number: str) -> str:
     return f"999-{(interchange_control_number or '').strip() or '000000001'}"
 
 
-@app.post("/api/parse-999")
+@app.post("/api/parse-999", dependencies=[Depends(matrix_gate)])
 async def parse_999_endpoint(
     request: Request,
     file: UploadFile = File(...),
@@ -718,7 +719,7 @@ def _ta1_synthetic_source_batch_id(interchange_control_number: str) -> str:
     return f"TA1-{(interchange_control_number or '').strip() or '000000001'}"
 
 
-@app.post("/api/parse-ta1")
+@app.post("/api/parse-ta1", dependencies=[Depends(matrix_gate)])
 async def parse_ta1_endpoint(
     file: UploadFile = File(...),
 ) -> Any:
@@ -797,7 +798,7 @@ async def parse_ta1_endpoint(
     })
 
 
-@app.get("/api/ta1-acks")
+@app.get("/api/ta1-acks", dependencies=[Depends(matrix_gate)])
 def list_ta1_acks_endpoint(
     limit: int = Query(100, ge=1, le=1000),
 ) -> Any:
@@ -815,7 +816,7 @@ def list_ta1_acks_endpoint(
     }
 
 
-@app.get("/api/ta1-acks/{ack_id}")
+@app.get("/api/ta1-acks/{ack_id}", dependencies=[Depends(matrix_gate)])
 def get_ta1_ack_endpoint(ack_id: int) -> dict:
     """Return one persisted TA1 ACK row with its parsed detail."""
     row = store.get_ta1_ack(ack_id)
@@ -861,7 +862,7 @@ def _277ca_synthetic_source_batch_id(interchange_control_number: str) -> str:
     return f"277CA-{(interchange_control_number or '').strip() or '000000001'}"
 
 
-@app.post("/api/parse-277ca")
+@app.post("/api/parse-277ca", dependencies=[Depends(matrix_gate)])
 async def parse_277ca_endpoint(
     request: Request,
     file: UploadFile = File(...),
@@ -980,7 +981,7 @@ async def parse_277ca_endpoint(
     })
 
 
-@app.get("/api/277ca-acks")
+@app.get("/api/277ca-acks", dependencies=[Depends(matrix_gate)])
 def list_277ca_acks_endpoint(
     limit: int = Query(100, ge=1, le=1000),
 ) -> Any:
@@ -990,7 +991,7 @@ def list_277ca_acks_endpoint(
     return {"total": len(rows), "items": items}
 
 
-@app.get("/api/277ca-acks/{ack_id}")
+@app.get("/api/277ca-acks/{ack_id}", dependencies=[Depends(matrix_gate)])
 def get_277ca_ack_endpoint(ack_id: int) -> dict:
     """Return one persisted 277CA ACK row with its parsed detail."""
     row = store.get_277ca_ack(ack_id)
@@ -1054,7 +1055,7 @@ def _serialize_ta1_from_row(row: db.Ta1Ack) -> str:
 # --------------------------------------------------------------------------- #
 
 
-@app.get("/api/inbox/lanes")
+@app.get("/api/inbox/lanes", dependencies=[Depends(matrix_gate)])
 def inbox_lanes():
     """Return all Inbox lanes in one call."""
     dismissed_pairs = getattr(app.state, "dismissed_pairs", set())
@@ -1072,7 +1073,7 @@ def inbox_lanes():
     }
 
 
-@app.post("/api/inbox/candidates/{remit_id}/match")
+@app.post("/api/inbox/candidates/{remit_id}/match", dependencies=[Depends(matrix_gate)])
 def inbox_match_candidate(remit_id: str, body: dict):
     """Manually link a remit to a claim."""
     claim_id = body.get("claim_id")
@@ -1101,7 +1102,7 @@ def inbox_match_candidate(remit_id: str, body: dict):
     return {"ok": True, "claim_id": claim_id, "remit_id": remit_id}
 
 
-@app.post("/api/inbox/candidates/dismiss")
+@app.post("/api/inbox/candidates/dismiss", dependencies=[Depends(matrix_gate)])
 def inbox_dismiss_candidates(body: dict):
     """Add candidate pairs to the session-scoped dismissed set."""
     pairs = body.get("pairs") or []
@@ -1115,7 +1116,7 @@ def inbox_dismiss_candidates(body: dict):
     return {"ok": True, "dismissed_count": len(pairs)}
 
 
-@app.post("/api/inbox/rejected/resubmit")
+@app.post("/api/inbox/rejected/resubmit", dependencies=[Depends(matrix_gate)])
 def inbox_resubmit_rejected(
     request: Request,
     body: dict,
@@ -1209,7 +1210,7 @@ def inbox_resubmit_rejected(
     )
 
 
-@app.get("/api/inbox/export.csv")
+@app.get("/api/inbox/export.csv", dependencies=[Depends(matrix_gate)])
 def inbox_export_csv(lane: str):
     """Stream a CSV for a single lane."""
     if lane not in {"rejected", "candidates", "unmatched", "done_today"}:
@@ -1262,7 +1263,7 @@ def _batch_summary_claim_count(rec: BatchRecord) -> int:
     return 0
 
 
-@app.get("/api/batches")
+@app.get("/api/batches", dependencies=[Depends(matrix_gate)])
 def list_batches(
     request: Request,
     limit: int = Query(100, ge=1, le=1000),
@@ -1296,7 +1297,7 @@ def list_batches(
     }
 
 
-@app.get("/api/batches/{batch_id}")
+@app.get("/api/batches/{batch_id}", dependencies=[Depends(matrix_gate)])
 def get_batch(batch_id: str) -> Any:
     rec = store.get(batch_id)
     if rec is None:
@@ -1307,7 +1308,7 @@ def get_batch(batch_id: str) -> Any:
     return json.loads(rec.result.model_dump_json())
 
 
-@app.get("/api/claims")
+@app.get("/api/claims", dependencies=[Depends(matrix_gate)])
 def list_claims(
     request: Request,
     batch_id: str | None = Query(None),
@@ -1418,7 +1419,7 @@ async def _tail_events(
         bus.unsubscribe(queue, kinds)
 
 
-@app.get("/api/claims/stream")
+@app.get("/api/claims/stream", dependencies=[Depends(matrix_gate)])
 async def claims_stream(
     request: Request,
     status: str | None = Query(None),
@@ -1465,7 +1466,7 @@ async def claims_stream(
     return StreamingResponse(gen(), media_type="application/x-ndjson")
 
 
-@app.get("/api/claims/{claim_id}")
+@app.get("/api/claims/{claim_id}", dependencies=[Depends(matrix_gate)])
 def get_claim_detail_endpoint(claim_id: str) -> dict:
     """Return one claim with full drawer context (SP4).
 
@@ -1490,7 +1491,7 @@ def get_claim_detail_endpoint(claim_id: str) -> dict:
     return body
 
 
-@app.get("/api/claims/{claim_id}/serialize-837")
+@app.get("/api/claims/{claim_id}/serialize-837", dependencies=[Depends(matrix_gate)])
 def serialize_claim_as_837(claim_id: str):
     """Return the claim as a regenerated X12 837P file (SP8).
 
@@ -1542,7 +1543,7 @@ def serialize_claim_as_837(claim_id: str):
     )
 
 
-@app.get("/api/claims/{claim_id}/line-reconciliation")
+@app.get("/api/claims/{claim_id}/line-reconciliation", dependencies=[Depends(matrix_gate)])
 def get_claim_line_reconciliation(claim_id: str) -> dict:
     """Per-line reconciliation view for the ClaimDrawer tab.
 
@@ -1739,7 +1740,7 @@ def _svc_to_dict(svc) -> dict:
     }
 
 
-@app.get("/api/reconciliation/unmatched")
+@app.get("/api/reconciliation/unmatched", dependencies=[Depends(matrix_gate)])
 def get_reconciliation_unmatched() -> dict:
     """Return unmatched Claims (left) and unmatched Remittances (right).
 
@@ -1756,7 +1757,7 @@ def get_reconciliation_unmatched() -> dict:
 # --------------------------------------------------------------------------- #
 
 
-@app.get("/api/batch-diff")
+@app.get("/api/batch-diff", dependencies=[Depends(matrix_gate)])
 def get_batch_diff(
     a: str | None = Query(None),
     b: str | None = Query(None),
@@ -1803,7 +1804,7 @@ def get_batch_diff(
     return diff_batches_to_wire(a_rec, b_rec)
 
 
-@app.post("/api/reconciliation/match")
+@app.post("/api/reconciliation/match", dependencies=[Depends(matrix_gate)])
 def post_reconciliation_match(body: dict) -> dict:
     """Manually pair a Claim with a Remittance (operator override).
 
@@ -1848,7 +1849,7 @@ def post_reconciliation_match(body: dict) -> dict:
         )
 
 
-@app.post("/api/reconciliation/unmatch")
+@app.post("/api/reconciliation/unmatch", dependencies=[Depends(matrix_gate)])
 def post_reconciliation_unmatch(body: dict) -> dict:
     """Remove the current match for a Claim; reset Claim to submitted.
 
@@ -1880,7 +1881,7 @@ def post_reconciliation_unmatch(body: dict) -> dict:
         )
 
 
-@app.get("/api/remittances")
+@app.get("/api/remittances", dependencies=[Depends(matrix_gate)])
 def list_remittances(
     request: Request,
     batch_id: str | None = Query(None),
@@ -1919,7 +1920,7 @@ def list_remittances(
     }
 
 
-@app.get("/api/remittances/stream")
+@app.get("/api/remittances/stream", dependencies=[Depends(matrix_gate)])
 async def remittances_stream(
     request: Request,
     payer: str | None = Query(None),
@@ -1958,7 +1959,7 @@ async def remittances_stream(
     return StreamingResponse(gen(), media_type="application/x-ndjson")
 
 
-@app.get("/api/remittances/{remittance_id}")
+@app.get("/api/remittances/{remittance_id}", dependencies=[Depends(matrix_gate)])
 def get_remittance(remittance_id: str) -> dict:
     """Return one remittance with its labeled CAS ``adjustments`` array.
 
@@ -1975,7 +1976,7 @@ def get_remittance(remittance_id: str) -> dict:
     return body
 
 
-@app.get("/api/providers")
+@app.get("/api/providers", dependencies=[Depends(matrix_gate)])
 def list_providers(
     request: Request,
     npi: str | None = Query(None),
@@ -2005,7 +2006,7 @@ def list_providers(
     }
 
 
-@app.get("/api/activity")
+@app.get("/api/activity", dependencies=[Depends(matrix_gate)])
 def list_activity(
     request: Request,
     kind: str | None = Query(None),
@@ -2037,7 +2038,7 @@ def list_activity(
 # --------------------------------------------------------------------------- #
 
 
-@app.get("/api/dashboard/summary")
+@app.get("/api/dashboard/summary", dependencies=[Depends(matrix_gate)])
 def dashboard_summary(
     months: int = Query(6, ge=1, le=24),
     top_providers: int = Query(4, ge=1, le=20),
@@ -2061,7 +2062,7 @@ def dashboard_summary(
     )
 
 
-@app.get("/api/activity/stream")
+@app.get("/api/activity/stream", dependencies=[Depends(matrix_gate)])
 async def activity_stream(
     request: Request,
     kind: str | None = Query(None),
@@ -2125,7 +2126,7 @@ def _ack_to_ui(row) -> dict:
     }
 
 
-@app.get("/api/acks")
+@app.get("/api/acks", dependencies=[Depends(matrix_gate)])
 def list_acks_endpoint(
     request: Request,
     limit: int = Query(100, ge=1, le=1000),
@@ -2149,7 +2150,7 @@ def list_acks_endpoint(
     }
 
 
-@app.get("/api/acks/{ack_id}")
+@app.get("/api/acks/{ack_id}", dependencies=[Depends(matrix_gate)])
 def get_ack_endpoint(ack_id: int) -> dict:
     """Return one persisted ACK row with its parsed detail.
 
@@ -2289,7 +2290,7 @@ def _validate_eligibility_request(body: dict) -> tuple[ParseResult270, str]:
     return result, service_type_code
 
 
-@app.post("/api/eligibility/request")
+@app.post("/api/eligibility/request", dependencies=[Depends(matrix_gate)])
 def post_eligibility_request(body: dict) -> Any:
     """Build a 270 eligibility inquiry from a small JSON body.
 
@@ -2315,7 +2316,7 @@ def post_eligibility_request(body: dict) -> Any:
     }
 
 
-@app.post("/api/eligibility/parse-271")
+@app.post("/api/eligibility/parse-271", dependencies=[Depends(matrix_gate)])
 async def post_eligibility_parse_271(
     file: UploadFile = File(...),
 ) -> Any:
@@ -2375,7 +2376,7 @@ async def post_eligibility_parse_271(
 # ---------------------------------------------------------------------------
 
 
-@app.get("/api/clearhouse")
+@app.get("/api/clearhouse", dependencies=[Depends(matrix_gate)])
 def get_clearhouse():
     """Return the singleton clearhouse config (dzinesco's identity, SFTP block, filename block)."""
     ch = store.get_clearhouse()
@@ -2384,7 +2385,7 @@ def get_clearhouse():
     return json.loads(ch.model_dump_json())
 
 
-@app.post("/api/clearhouse/submit")
+@app.post("/api/clearhouse/submit", dependencies=[Depends(matrix_gate)])
 def submit_to_clearhouse(body: dict):
     """Submit a batch of claims to the clearhouse (SFTP). SP9: stub.
 
@@ -2484,7 +2485,7 @@ def _serialize_claim_from_raw(claim_row, raw: dict) -> str:
     )
 
 
-@app.get("/api/config/providers")
+@app.get("/api/config/providers", dependencies=[Depends(matrix_gate)])
 def list_configured_providers(is_active: bool | None = Query(default=True)):
     """List the configured provider rows (3 NPIs for SP9)."""
     return [json.loads(p.model_dump_json()) for p in store.list_providers(is_active=is_active)]
@@ -2495,7 +2496,7 @@ def list_configured_providers(is_active: bool | None = Query(default=True)):
 # --------------------------------------------------------------------------- #
 
 
-@app.get("/api/admin/audit-log")
+@app.get("/api/admin/audit-log", dependencies=[Depends(matrix_gate)])
 def list_audit_log_endpoint(
     entity_type: str | None = Query(default=None),
     entity_id: str | None = Query(default=None),
@@ -2537,7 +2538,7 @@ def list_audit_log_endpoint(
         }
 
 
-@app.get("/api/admin/audit-log/verify")
+@app.get("/api/admin/audit-log/verify", dependencies=[Depends(matrix_gate)])
 def verify_audit_log_endpoint() -> Any:
     """Walk the audit-log chain and verify every row's hash.
 
@@ -2556,7 +2557,7 @@ def verify_audit_log_endpoint() -> Any:
     }
 
 
-@app.get("/api/config/providers/{npi}")
+@app.get("/api/config/providers/{npi}", dependencies=[Depends(matrix_gate)])
 def get_configured_provider(npi: str):
     p = store.get_provider(npi)
     if p is None:
@@ -2564,12 +2565,12 @@ def get_configured_provider(npi: str):
     return json.loads(p.model_dump_json())
 
 
-@app.get("/api/config/payers")
+@app.get("/api/config/payers", dependencies=[Depends(matrix_gate)])
 def list_configured_payers(is_active: bool | None = Query(default=True)):
     return [json.loads(p.model_dump_json()) for p in store.list_payers(is_active=is_active)]
 
 
-@app.get("/api/config/payers/{payer_id}/configs")
+@app.get("/api/config/payers/{payer_id}/configs", dependencies=[Depends(matrix_gate)])
 def list_payer_configs(payer_id: str):
     """List all (transaction_type, config_json) blocks for a payer."""
     from cyclone import payers as payer_loader
@@ -2586,7 +2587,7 @@ def list_payer_configs(payer_id: str):
     return configs
 
 
-@app.post("/api/admin/reload-config")
+@app.post("/api/admin/reload-config", dependencies=[Depends(matrix_gate)])
 def reload_config():
     """Re-read ``config/payers.yaml`` and revalidate. Returns counts."""
     from cyclone import payers as payer_loader
diff --git a/backend/src/cyclone/auth/deps.py b/backend/src/cyclone/auth/deps.py
index 4660381..67f78ce 100644
--- a/backend/src/cyclone/auth/deps.py
+++ b/backend/src/cyclone/auth/deps.py
@@ -102,3 +102,40 @@ def require_role(*allowed: Role):
             )
         return user
     return _dep
+
+
+async def matrix_gate(
+    request: Request,
+    user: dict = Depends(get_current_user),
+) -> dict:
+    """App-wide gate: requires auth, then enforces the PERMISSIONS matrix.
+
+    Behavior:
+    * AUTH_DISABLED short-circuits (synthetic admin, no role check).
+    * No session cookie → 401 from get_current_user.
+    * Endpoint not in the matrix → 403 (fail-closed).
+    * User role not allowed for (method, path) → 403.
+    * Empty allowed-roles set (e.g. /api/healthz) → public, no role check.
+
+    Used as the single ``dependencies=[Depends(matrix_gate)]`` on every
+    authenticated route in ``cyclone.api``. Centralizing the gate here
+    means the matrix is the source of truth — no need to wire per-route
+    ``require_role(...)`` calls.
+    """
+    if AUTH_DISABLED:
+        return user
+    method = request.method
+    path = request.url.path
+    roles = allowed_roles(method, path)
+    if roles is None:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail="forbidden",
+        )
+    user_role = user.get("role")
+    if user_role not in {r.value for r in roles}:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail="forbidden",
+        )
+    return user
diff --git a/backend/tests/conftest.py b/backend/tests/conftest.py
index 0ee2b75..148a69c 100644
--- a/backend/tests/conftest.py
+++ b/backend/tests/conftest.py
@@ -10,26 +10,51 @@ requires the engine to be initialized before any DB access, whereas the
 old in-memory store did not. Adding the init here keeps existing test
 modules (test_api.py, test_api_835.py, test_api_gets.py,
 test_api_parse_persists.py) working unchanged.
+
+Auth posture: ``CYCLONE_AUTH_DISABLED`` defaults to ``"1"`` here so the
+existing test suite (700+ tests that don't log in) continues to pass
+unmodified. Tests in ``test_auth_*`` modules explicitly re-enable auth
+so they exercise the real ``get_current_user`` / ``matrix_gate`` paths.
 """
 
 from __future__ import annotations
 
+import os
+
+# Must be set before ``cyclone.api`` is imported so ``get_current_user``
+# / ``matrix_gate`` see the env var. The module-level ``AUTH_DISABLED``
+# flag in ``cyclone.auth.deps`` is flipped per-test below.
+os.environ.setdefault("CYCLONE_AUTH_DISABLED", "1")
+
 import pytest
 
 
 @pytest.fixture(autouse=True)
-def _auto_init_db(tmp_path, monkeypatch):
+def _auto_init_db(tmp_path, monkeypatch, request):
     """Point CYCLONE_DB_URL at a per-test SQLite file and init the schema.
 
     Also wires a fresh ``EventBus`` onto ``app.state`` because ``TestClient``
     does not invoke the FastAPI lifespan handler unless used as a context
     manager. The bus is reset between tests so subscribers don't leak.
+
+    Auth posture is set per-test from the test module's name: legacy
+    tests (any module not starting with ``test_auth``) run with
+    ``AUTH_DISABLED=True`` so they hit the API without logging in;
+    ``test_auth_*`` modules run with ``AUTH_DISABLED=False`` so they
+    exercise the real ``get_current_user`` / ``matrix_gate`` paths.
     """
     monkeypatch.setenv("CYCLONE_DB_URL", f"sqlite:///{tmp_path}/test.db")
     from cyclone import db
     from cyclone.api import app
+    from cyclone.auth import deps as _auth_deps
     from cyclone.pubsub import EventBus
 
+    test_module = request.node.module.__name__
+    if test_module.startswith("test_auth"):
+        _auth_deps.AUTH_DISABLED = False
+    else:
+        _auth_deps.AUTH_DISABLED = True
+
     db._reset_for_tests()
     db.init_db()
     app.state.event_bus = EventBus()
diff --git a/backend/tests/test_existing_endpoints_require_auth.py b/backend/tests/test_existing_endpoints_require_auth.py
new file mode 100644
index 0000000..cadd03d
--- /dev/null
+++ b/backend/tests/test_existing_endpoints_require_auth.py
@@ -0,0 +1,70 @@
+"""Spot-check that existing endpoints now require auth (when AUTH_DISABLED is not set).
+
+The conftest in ``tests/conftest.py`` flips ``AUTH_DISABLED=True`` for
+every test module that does NOT start with ``test_auth`` — this module
+deliberately is NOT named ``test_auth_*`` so it inherits the default
+disabled posture... wait, that's the opposite of what we want.
+
+This module is named ``test_existing_endpoints_require_auth`` so the
+conftest will treat it as a legacy test and set ``AUTH_DISABLED=True``,
+bypassing the auth check entirely. To actually verify the gate, this
+test's ``client`` fixture flips ``AUTH_DISABLED`` to ``False``
+*just for this test*, then restores it afterwards. This way the
+rest of the suite still sees the disabled posture and existing
+tests keep passing.
+"""
+
+from __future__ import annotations
+
+import pytest
+from fastapi.testclient import TestClient
+from sqlalchemy import delete
+
+from cyclone.api import app
+from cyclone.auth import deps as _auth_deps
+from cyclone.auth.deps import AUTH_DISABLED
+from cyclone.db import Session as DbSession
+from cyclone.db import SessionLocal, User
+
+
+@pytest.fixture(autouse=True)
+def _clear():
+    with SessionLocal()() as db:
+        db.execute(delete(DbSession))
+        db.execute(delete(User))
+        db.commit()
+    yield
+    with SessionLocal()() as db:
+        db.execute(delete(DbSession))
+        db.execute(delete(User))
+        db.commit()
+
+
+@pytest.fixture
+def client():
+    # Force AUTH_DISABLED=False for these tests so the dep actually checks the cookie.
+    original = AUTH_DISABLED
+    _auth_deps.AUTH_DISABLED = False
+    try:
+        yield TestClient(app)
+    finally:
+        _auth_deps.AUTH_DISABLED = original
+
+
+@pytest.mark.parametrize("method,path", [
+    ("GET", "/api/claims"),
+    ("GET", "/api/remittances"),
+    ("GET", "/api/providers"),
+    ("GET", "/api/batches"),
+    ("GET", "/api/dashboard/summary"),
+    ("GET", "/api/activity"),
+])
+def test_existing_get_endpoints_require_auth(client, method, path):
+    resp = client.request(method, path)
+    assert resp.status_code == 401, f"{method} {path} returned {resp.status_code}"
+
+
+def test_health_is_public(client):
+    """``/api/health`` is the public healthcheck and must remain reachable."""
+    resp = client.get("/api/health")
+    assert resp.status_code != 401, f"/api/health returned {resp.status_code}"