diff --git a/agent/src/agent/firefly.py b/agent/src/agent/firefly.py
new file mode 100644
index 0000000..b588b22
--- /dev/null
+++ b/agent/src/agent/firefly.py
@@ -0,0 +1,49 @@
+"""Minimal read-only client for the Firefly III REST API."""
+
+from __future__ import annotations
+
+import httpx
+
+
+class FireflyError(Exception):
+    """Firefly III returned an unexpected response."""
+
+
+class FireflyClient:
+    def __init__(
+        self,
+        base_url: str,
+        token: str,
+        transport: httpx.BaseTransport | None = None,
+    ) -> None:
+        self._http = httpx.Client(
+            base_url=base_url,
+            headers={
+                "Authorization": f"Bearer {token}",
+                "Accept": "application/json",
+            },
+            timeout=30.0,
+            transport=transport,
+        )
+
+    def _get(self, path: str, params: dict | None = None) -> dict:
+        response = self._http.get(path, params=params)
+        if response.status_code != 200:
+            raise FireflyError(
+                f"GET {path} -> {response.status_code}: {response.text[:200]}"
+            )
+        return response.json()
+
+    def about(self) -> dict:
+        return self._get("/api/v1/about")["data"]
+
+    def accounts(self, type: str = "asset") -> list[dict]:
+        results: list[dict] = []
+        page = 1
+        while True:
+            body = self._get("/api/v1/accounts", params={"type": type, "page": page})
+            results.extend(body["data"])
+            pagination = body.get("meta", {}).get("pagination", {})
+            if page >= pagination.get("total_pages", 1):
+                return results
+            page += 1
diff --git a/agent/tests/test_firefly.py b/agent/tests/test_firefly.py
new file mode 100644
index 0000000..efc64d5
--- /dev/null
+++ b/agent/tests/test_firefly.py
@@ -0,0 +1,49 @@
+import httpx
+import pytest
+
+from agent.firefly import FireflyClient, FireflyError
+
+
+def make_client(handler) -> FireflyClient:
+    return FireflyClient(
+        "http://firefly.test", "tok", transport=httpx.MockTransport(handler)
+    )
+
+
+def test_about_sends_bearer_token_and_returns_data():
+    def handler(request: httpx.Request) -> httpx.Response:
+        assert request.headers["Authorization"] == "Bearer tok"
+        assert request.headers["Accept"] == "application/json"
+        assert request.url.path == "/api/v1/about"
+        return httpx.Response(200, json={"data": {"version": "6.1.1"}})
+
+    assert make_client(handler).about() == {"version": "6.1.1"}
+
+
+def test_non_200_raises_firefly_error_with_status():
+    def handler(request: httpx.Request) -> httpx.Response:
+        return httpx.Response(401, json={"message": "Unauthenticated"})
+
+    with pytest.raises(FireflyError, match="401"):
+        make_client(handler).about()
+
+
+def test_accounts_walks_all_pages():
+    def handler(request: httpx.Request) -> httpx.Response:
+        assert request.url.path == "/api/v1/accounts"
+        assert request.url.params["type"] == "asset"
+        page = int(request.url.params.get("page", "1"))
+        data = {
+            1: [{"id": "1", "attributes": {"name": "NFCU Checking"}}],
+            2: [{"id": "2", "attributes": {"name": "Venmo"}}],
+        }[page]
+        return httpx.Response(
+            200,
+            json={
+                "data": data,
+                "meta": {"pagination": {"total_pages": 2, "current_page": page}},
+            },
+        )
+
+    accounts = make_client(handler).accounts()
+    assert [a["attributes"]["name"] for a in accounts] == ["NFCU Checking", "Venmo"]