Close Milestone 4 with adapter adoption evidence

docs/COMPATIBILITY.md

@@ -31,16 +31,31 @@ model, index, rendering, application, and MCP factory names imported from these
 remain supported:
 
 - `docforge.adapter_contract`
+- `docforge.adapter_sdk`
+- `docforge.adapter_launcher`
 - `docforge.application`
+- `docforge.client_config`
 - `docforge.index`
 - `docforge.mcp_server`
 - `docforge.models`
 - `docforge.policy`
 - `docforge.render_contract`
+- `docforge.reference_config`
+- `docforge.reference_mcp`
 
 Names beginning with an underscore are implementation details. New public names may be added
 without breaking this contract.
 
+The repository Python, JavaScript/TypeScript, and C++ adapters are supported reference
+implementations. Their documented configuration, evidence limits, and unsupported-fact reports are
+compatibility surfaces; their internal parser helpers are not adapter-authoring imports.
+
+Milestone 4 adds three version-1 schemas without changing existing descriptor or result schemas:
+
+- `schemas/adapter-launcher.schema.json`
+- `schemas/adapter-client-configuration.schema.json`
+- `schemas/reference-adapter.schema.json`
+
 ## CLI and MCP surfaces
 
 Existing `docforge` command names and arguments remain supported. Existing `docforge-mcp` tool
@@ -233,6 +248,11 @@ Milestone 3 adds `ManualRenderPlanV1`, `GraphViewPlanV1`, projection package and
 and projection policy version 2. These are additive submodule and schema contracts. They do not
 change the legacy task-context, adapter, changeset, or effective-policy contracts described above.
 
+Milestone 4 adds `docforge.adapter_sdk`, the fixed reference configuration and read-only MCP
+binding, immutable adapter launchers, and generated adapter client fragments. A legacy adapter with
+only `load_projection()` remains first-class and need not adopt incremental extraction, Logic, a
+reference configuration, or launcher metadata.
+
 ## Safety boundary
 
 DocForge remains bound to one explicit project root. It rejects absolute paths, root escapes, and
@@ -245,8 +265,9 @@ publication, or project switching.
 Milestone 0 records rather than redesigns these areas:
 
 - Generic warm reads still repeat whole-project discovery, parsing, and validation.
-- Tree-sitter and the JavaScript and C++ grammars remain mandatory installation dependencies even
-  when their runtime modules are unused.
+- The base wheel intentionally omits Tree-sitter. JavaScript, TypeScript, and C++ syntax evidence
+  requires the matching `docforge[javascript]`, `docforge[typescript]`, or `docforge[cpp]` extra.
+  Python reference evidence uses the standard library and remains available in the base wheel.
 - Several version strings and defaults remain duplicated.
 - One individually oversized context entry is represented as explicit bounded omission evidence;
   callers use targeted retrieval for that node.