Add MCP compatibility ledger tool and first-pass Go/Rust codegen hardening

docs/mcp_compatibility_ledger.json

@@ -0,0 +1,26 @@
+{
+  "ledger_version": "2026-02-26",
+  "records": [
+    {
+      "id": "MCP-GORUST-FIRSTPASS-LEGALITY",
+      "title": "Go/Rust first-pass legality normalization",
+      "status": "fixed",
+      "introduced_in": "0.8.1",
+      "fixed_in": "0.8.4",
+      "affected_tools": [
+        "whetstone_generate_code",
+        "whetstone_run_pipeline"
+      ],
+      "symptoms": [
+        "Go outputs missing package/import/type details",
+        "Rust outputs using print/println in non-macro form",
+        "High deterministic fixer hit-rate before ready"
+      ],
+      "verification": [
+        "run_ast_once_vs_direct_matrix: direct_fix_applied_rate approaches 0%",
+        "run_ast_once_vs_direct_matrix: ast_fix_applied_rate approaches 0%"
+      ],
+      "notes": "Deterministic generator/projection defaults were tightened to emit legal Go/Rust first-pass code."
+    }
+  ]
+}

docs/mcp_versioning_and_compatibility.md

@@ -0,0 +1,45 @@
+# MCP Versioning and Compatibility (Agent Guide)
+
+## Why this exists
+Agents can fail for reasons that are already fixed in newer MCP runtime builds. This guide defines where to check runtime/tool versions and where fix records are tracked.
+
+## Runtime version header
+Whetstone MCP now exposes a `whetstoneVersionHeader` in:
+- `initialize.result`
+- `ping.result`
+- `tools/list.result`
+- `tools/call.result`
+
+Header fields:
+- `runtimeVersion`: MCP runtime version (for example `0.8.4`)
+- `protocolVersion`: MCP protocol date string
+- `toolContractDefaultVersion`: default contract version for tools
+- `toolSurfaceSchemaVersion`: schema snapshot version
+- `toolCount`: tool count in the running server
+- `toolSurfaceFingerprint`: deterministic fingerprint of tool names
+- `compatibilityLedger.path`: path to the issue/fix ledger JSON
+- `compatibilityLedger.version`: ledger schema/snapshot version
+
+## Tool-level contract header
+Each `tools/list` entry includes `x-whetstone`:
+- `contractVersion`
+- `compatibilityLedger`
+
+## Compatibility ledger
+Machine-readable ledger:
+- `docs/mcp_compatibility_ledger.json`
+
+Use this for checks like:
+- "Issue reproduced on `runtimeVersion=0.8.1`"
+- "Ledger says fixed in `0.8.4`"
+- "Action: update server runtime before more debugging"
+
+## Recommended triage flow for agents
+1. Call `initialize` (or `ping`) and capture `whetstoneVersionHeader`.
+2. If behavior seems wrong, read `docs/mcp_compatibility_ledger.json` and match symptom tags.
+3. If `runtimeVersion < fixed_in`, report upgrade recommendation first.
+4. Only escalate to deep debugging after version mismatch is ruled out.
+
+## Notes
+- Keep ledger entries small and concrete (symptom, affected tools, fixed version).
+- Add entries when a recurring failure pattern is fixed deterministically.

docs/sprint166_168_taskitem_execution_log_2026-02-26.md

@@ -68,3 +68,28 @@ Observed result:
 Result:
 
 - `overall_ready=true` within iteration budget for PriorityQueue spec.
+
+## MCP versioning/compatibility rollout (2026-02-26)
+
+Implemented baseline compatibility/versioning support for multi-agent MCP usage:
+
+- Added MCP runtime/tool version metadata in protocol responses:
+  - `editor/src/MCPServer.h`
+  - `editor/src/mcp_main.cpp`
+- Added compatibility docs + machine-readable ledger:
+  - `docs/mcp_versioning_and_compatibility.md`
+  - `docs/mcp_compatibility_ledger.json`
+  - `tools/mcp/README.md` (version check flow)
+- Added MCP tool for agents to query compatibility data directly:
+  - `editor/src/mcp/RegisterCompatibilityTools.h`
+  - registered via:
+    - `editor/src/mcp/RegisterOnboardingAndAllTools.h`
+    - `editor/src/MCPServer.h` include
+
+Validation:
+
+- Rebuilt target: `whetstone_mcp`
+- Verified `tools/call`:
+  - `whetstone_get_compatibility_ledger` returns:
+    - runtime header (`runtimeVersion`, `toolSurfaceFingerprint`, etc.)
+    - parsed ledger contents from `docs/mcp_compatibility_ledger.json`