Milestones and review in the new loop (M2.1, PR C)

A work item starts from a fresh workspace: fetch, set aside (never
discard) leftover changes, branches and unpushed commits, a clean default
branch, and a branch of its own (D3, #62). start_milestone cuts the
milestone's branch; finish_milestone commits only the work, pushes and
opens a PR that closes the issue, under an intent, adopting an open PR and
treating a closed one as the operator's answer (D4). Between runs the
loop watches each item's PR: operator comments and inline review notes
(#69) reach the item, a merge or close hands back to the driver. A review
fix is checked after it's pushed and goes out as a new PR if the PR merged
first (D5). At boot an interrupted publish is settled against Gitea (L8).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPQ14L3LikyefCMFBqEbKE

nisse-dev/src/nisse_dev/loop/tools.py

@@ -5,11 +5,11 @@ the item then waits on the operator."""
 from typing import Any
 
 
-def _tool(name: str, description: str, **params: str) -> dict[str, Any]:
+def _tool(tool: str, description: str, /, **params: str) -> dict[str, Any]:
     return {
         "type": "function",
         "function": {
-            "name": name,
+            "name": tool,
             "description": description,
             "parameters": {
                 "type": "object",
@@ -42,7 +42,22 @@ CLOSE_ITEM = _tool(
     summary="What was done, verified, and left open.",
 )
 
-WAITING = frozenset({"restate", "ask_human", "close_item"})
+START_MILESTONE = _tool(
+    "start_milestone",
+    "Start a milestone before changing code: the harness cuts its branch. "
+    "Never create or switch branches yourself.",
+    name="A short name for the milestone.",
+)
+FINISH_MILESTONE = _tool(
+    "finish_milestone",
+    "The milestone's work is done and its tests pass: the harness commits "
+    "the work, pushes it and opens a PR, or, after review comments, pushes "
+    "your fix to the PR. Ends your turn; you continue when the PR is "
+    "reviewed or merged.",
+    summary="What the milestone did and how it was verified, for the PR.",
+)
+
+WAITING = frozenset({"restate", "ask_human", "close_item", "finish_milestone"})
 
 
 def names(tools: list[dict[str, Any]]) -> set[str]: