Harness foundation: INTENT, ADR-001, architecture, prototype adoption

- INTENT.md: three-layer model (blueprint/instance/harness), single
  shared runtime, never-become boundaries
- ADR-001 (accepted): DEC-2026-002 resolution — one harness repo for
  all projects; instances are declarative state in consuming repos
- docs/architecture.md: components, contracts (manifest, tool
  profiles, completion events, credential lanes), deployment shape
- agent_harness/: executor-worker prototype adopted and renamed
  (6/6 tests green); HARNESS-WP-0001 initial workplan (7 tasks)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

agent_harness/adapter.py

@@ -0,0 +1,83 @@
+"""Agentic Claude Code adapter.
+
+llm-connect's ClaudeCodeAdapter is a text-generation adapter (`claude
+--print`, no working directory, no tool grants). An executor run needs an
+*agentic* session: file edits and git commits inside the target repo, under
+a hard tool allow-list. This adapter subclasses it, keeping the llm-connect
+LLMAdapter interface so a hosted adapter can be swapped in later, and adds:
+
+- cwd pinned to the target repo
+- --permission-mode acceptEdits
+- an allow-list identical in spirit to binky-control/scripts/rhythm-session.sh:
+  read/edit tools plus local git add/commit/status/log/diff — no push, no
+  network, no arbitrary shell.
+"""
+
+from __future__ import annotations
+
+import subprocess
+from pathlib import Path
+
+from llm_connect.claude_code import ClaudeCodeAdapter
+from llm_connect.exceptions import LLMSubprocessError, LLMTimeoutError
+from llm_connect.models import LLMResponse, RunConfig
+
+ALLOWED_TOOLS = (
+    "Read,Write,Edit,Glob,Grep,"
+    "Bash(git add:*),Bash(git commit:*),Bash(git status),"
+    "Bash(git log:*),Bash(git diff:*),Bash(date:*),Bash(ls:*)"
+)
+
+
+class AgenticClaudeCodeAdapter(ClaudeCodeAdapter):
+    def __init__(self, workdir: Path, **kwargs):
+        super().__init__(**kwargs)
+        self._workdir = workdir
+
+    def _build_command(self, config: RunConfig) -> list[str]:
+        cmd = [
+            self._cli_path,
+            "--print",
+            "--permission-mode",
+            "acceptEdits",
+            "--allowedTools",
+            ALLOWED_TOOLS,
+        ]
+        if self._model:
+            cmd.extend(["--model", self._model])
+        return cmd
+
+    def execute_prompt(self, prompt: str, config: RunConfig) -> LLMResponse:
+        self._preflight_budget(config)
+        cmd = self._build_command(config)
+        timeout = config.timeout_seconds or self._config.timeout_seconds
+        try:
+            result = subprocess.run(
+                cmd,
+                input=prompt,
+                capture_output=True,
+                text=True,
+                timeout=timeout,
+                cwd=self._workdir,
+            )
+        except subprocess.TimeoutExpired as exc:
+            raise LLMTimeoutError(
+                f"claude CLI timed out after {timeout}s", cause=exc
+            ) from exc
+        if result.returncode != 0:
+            raise LLMSubprocessError(
+                f"claude CLI exited with code {result.returncode}",
+                return_code=result.returncode,
+                stderr=result.stderr,
+            )
+        return LLMResponse(
+            content=result.stdout,
+            model=self._model or "claude-code-cli",
+            usage={},
+            finish_reason="stop",
+            metadata={
+                "provider": "claude-code-agentic",
+                "cli_path": self._cli_path,
+                "workdir": str(self._workdir),
+            },
+        )