diff --git a/GOVERNANCE.md b/GOVERNANCE.md
new file mode 100644
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@@ -0,0 +1,56 @@
+# Governance
+
+How decisions about this specification are made, by whom, and what happens
+when that has to change. Complements [VERSIONING.md](VERSIONING.md) (what a
+change breaks) and [CONTRIBUTING.md](CONTRIBUTING.md) (how to propose one).
+
+## Roles
+
+- **Maintainer** — currently one: [1o1 Co. Ltd.](https://1o1.co.jp/). The
+  maintainer merges changes, cuts tags, and owns the `dplaax.dev` namespace
+  publish root (`site/`).
+- **Contributors** — anyone, through public Issues and pull requests. All
+  discussion is public; there is no private decision channel.
+
+## Change classes and required procedure
+
+| Class | Examples | Procedure |
+| --- | --- | --- |
+| Editorial | prose clarification, typo, link | PR; maintainer merge |
+| Additive | new rule (`status: todo`/`draft`), new vectors | Issue describing the norm, then a PR carrying the rule and its vectors; maintainer merge |
+| Semantic | changing what an existing rule id asserts | Public proposal issue stating the compatibility impact per [VERSIONING.md](VERSIONING.md); explicit maintainer approval recorded on the issue |
+| Namespace | anything under the published `site/` paths | Frozen once shipped — a semantic change requires a NEW path (`/v2`, a new grant name), never mutation of an existing one |
+
+## Rule promotion: draft → stable
+
+A rule is promoted from `draft` to `stable` when its conformance vectors are
+passed by **two independent implementations**. Until a second implementation
+exists, rules stay `draft` — deliberately: the promotion criterion doubles as
+a standing invitation for that second implementation. (`todo → draft`
+promotion freezes the rule id — see the README's id discipline.)
+
+## Decision method
+
+Single-maintainer discretion, exercised in public: proposals, objections, and
+the decision itself are recorded on the issue that carries them. Before a
+second maintainer from another organization lands, this document will be
+revised to a consensus model with explicit escalation rules — single-company
+authority is not the intended end state.
+
+## Succession and forks
+
+- If the maintainer is unresponsive for **six months** to a good-faith
+  contact attempt (a public issue plus the contact routes published by the
+  maintainer), any party may fork and continue under the Apache-2.0 terms.
+  Nothing in this project impedes a fork.
+- Already-issued credentials do not depend on this repository's fate for
+  verification: the JSON-LD contexts are sha256-pinned and embedded in
+  evidence bundles, so offline verification survives the namespace. The
+  continuity plan for live resolution of `dplaax.dev` is tracked as its own
+  workstream.
+
+## IPR
+
+Inbound = outbound: contributions are accepted under the repository's
+Apache-2.0 license, which carries an express patent grant. A DCO sign-off
+requirement may be added later; it is not required today.
diff --git a/README.md b/README.md
index 45c7776..5918de4 100644
--- a/README.md
+++ b/README.md
@@ -9,9 +9,11 @@ the resulting chain can be independently verified by third parties
 > **Status: v0.1 (draft).** All rules are in `draft` state and will continue to
 > evolve based on implementation feedback (→ [VERSIONING.md](VERSIONING.md)).
 > **Public review and contributions are welcome** —
-> see [CONTRIBUTING.md](CONTRIBUTING.md). Governance will be formalized
-> incrementally as the contributor base grows (current state: maintainer
-> discretion; discussions are public in Issues).
+> see [CONTRIBUTING.md](CONTRIBUTING.md). Governance — who decides, change
+> classes, draft→stable promotion, succession — is documented in
+> [GOVERNANCE.md](GOVERNANCE.md). Known implementation:
+> [provin-line/oss](https://github.com/provin-line/oss) (v0.3.0 tracks spec
+> v0.1 draft; vendors and CI-gates this repo's `vectors/`).
 
 The normative spec for dPLaaX. **The source of truth for all normative content
 is exactly the following three artifacts**; prose is non-normative.