diff --git a/AGENTS.md b/AGENTS.md
index 33de5fb..82b4b6b 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -56,8 +56,20 @@ docs/TECHNICAL-DESIGN.md
 docs/BACKUPS.md                # backup, verification and restore runbook
 docs/DEPLOYMENT.md             # deploy, rollback and operations
 docs/HANDOFF.md                # next task prompt and backlog
+docs/adr/                      # one file per irreversible decision
 ```
 
+## Documentation Policy
+
+Docs capture decisions and current state, never session narration.
+
+- **Allowed:** this file, `README`, `docs/TECHNICAL-DESIGN.md`, `docs/adr/NNN-*.md` (one decision:
+  context, options, decision, consequences), the runbooks (`BACKUPS`, `DEPLOYMENT`) and
+  `docs/HANDOFF.md`.
+- **Forbidden:** phase reports, progress logs, "what I did" narration and per-session summaries.
+  When a change needs a durable record, update the design doc or add an ADR — do not create a
+  report file. This applies to AI output too.
+
 ## Commands
 
 | Task | Command |
diff --git a/docs/adr/README.md b/docs/adr/README.md
new file mode 100644
index 0000000..cd85033
--- /dev/null
+++ b/docs/adr/README.md
@@ -0,0 +1,9 @@
+# Architecture Decision Records
+
+One file per irreversible or costly decision: `NNN-title.md` with **Context**, **Options**,
+**Decision** and **Consequences**. Written by the human, in a few paragraphs — not generated as a
+report.
+
+Use an ADR when a choice is hard to reverse or future-you needs the *why* (money as `long`, money
+in exact pesos, ownership enforced twice, history indestructible). For everyday changes, update the
+relevant [spec](../specs/) and the code instead.