diff --git a/AGENTS.md b/AGENTS.md
new file mode 100644
index 0000000..56b6a31
--- /dev/null
+++ b/AGENTS.md
@@ -0,0 +1,36 @@
+# Agents
+
+These are the rules for agents working on this repository.
+
+## Branches
+
+- `main` is the stable branch, and `next` is the development branch.
+- Every PR is cut from `next` and targets `next`.
+- Only sneak merges `next` into `main`.
+- Each issue lands on `next` as one squashed commit whose title ends
+  ` (closes #N)`.
+
+## Entrypoints
+
+- Work through the `Makefile` targets, which call the scripts in `script/`. The
+  README's [Entrypoints](README.md#entrypoints) section lists them.
+- Never run `go`, `golangci-lint` or prettier directly.
+- `make check` passes before every push.
+
+## Editing
+
+- Edit files by hand.
+- Format only with `make fmt`, and run it before committing any change.
+
+## Iron rules
+
+- The request log records query strings exactly as received.
+    - Secrets belong in POST data. An app that puts a secret in a query string
+      is fixed in the app.
+    - Never propose redacting a query string, Gitea's `?token=` included.
+- The default of `SWRP_TRUSTED_PROXIES` is the RFC 1918 set:
+    - `10.0.0.0/8`;
+    - `172.16.0.0/12`;
+    - `192.168.0.0/16`.
+- `SPEC.md` states that default. Forwarded headers count only when the peer is a
+  trusted proxy.
diff --git a/README.md b/README.md
index 8799b16..c2a10e2 100644
--- a/README.md
+++ b/README.md
@@ -740,6 +740,7 @@ on the host.
 - [`EVALUATION.md`](EVALUATION.md): what already exists, what each tool covers
   and misses, and why none was adopted.
 - [`REPO_POLICIES.md`](REPO_POLICIES.md): the policies this repository follows.
+- [`AGENTS.md`](AGENTS.md): the rules for agents working on this repository.
 - [`docs/settings.md`](docs/settings.md): every setting and the values it takes.
 - [`docs/rules.md`](docs/rules.md): the rule file format and the default file.
 - [`docs/admin-endpoints.md`](docs/admin-endpoints.md): the endpoints under
diff --git a/SPEC.md b/SPEC.md
index e3b5123..4c195db 100644
--- a/SPEC.md
+++ b/SPEC.md
@@ -133,6 +133,8 @@ request log's `heuristic` field gives that name. `refusal_limit` and
 1. `GET /_sww/healthz` is answered at once by `rproxy`, before any check, so a
    health checker never needs an exemption and is never refused.
 2. The client is identified.
+    - `SWRP_TRUSTED_PROXIES` is `10.0.0.0/8`, `172.16.0.0/12` and
+      `192.168.0.0/16` by default. A list given replaces them.
     - If the TCP peer is inside `SWRP_TRUSTED_PROXIES`, `X-Forwarded-For` is
       walked from the right, and the first address outside those netblocks is
       the client. If every address is inside them, the leftmost is, so that a