New projects from conversation (M2.5, PR B)

- propose_project(name, purpose, decisions) in a conversation goes up for
  a go-ahead (checked: a slug, not an existing project, no trailing
  question).
- On go, the provisioning checklist (D1): a repository with a README,
  protection on its default branch, the agent as a collaborator, a build
  VM, a deploy key, and the project entry as YAML with <...> to fill in.
- On "done", the agent reads its configuration again and adds the new
  project live (build_loop_agent(load=...); only additions), then checks
  what was provided (D4, verified, not assumed): permissions and
  protection as it sees them, then on a throwaway branch with an empty
  commit, a branch push must succeed and a push to the default branch and
  merging its own PR must be refused. The check's PR is closed and its
  branch deleted. Failures are said per item; nothing starts.
- Checked: the tracking issue (the distilled decisions, carrying the new
  item's ID), and the project's item, agreed and labelled `design`, whose
  first milestone is ARCHITECTURE.md and the build plan. A conversation
  waiting on provisioning doesn't close as idle.
- The walk replays exactly from its seed (item IDs too), and event IDs
  stay unique across simulated restarts, as a server's are.
- The test config holds output to 8192 tokens, under the test key's
  per-request cost cap.

Tests: new-project unit tests (checklist and its YAML parse as config, done
before the entry, what isn't set up, a checked project's record and first
PR, an existing name), protection enforced by a hook on the fake forge,
the walk proposing projects and saying done, and an e2e new project in a
repository the test operator provisions from the agent's checklist.

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

nisse-dev/tests/test_loop_milestones.py

@@ -14,7 +14,7 @@ from nisse_dev.cancel import Cancel
 from nisse_dev.canonical import ToolCall
 from nisse_dev.execution import SSHHost
 from nisse_dev.git import GitRepo
-from nisse_dev.gitea import Comment, Issue, PullRequest, ReviewNote
+from nisse_dev.gitea import Comment, GiteaError, Issue, PullRequest, ReviewNote
 from nisse_dev.loop.agent import LoopAgent
 from nisse_dev.loop.driver import Driver
 from nisse_dev.loop.items import ANSWER, MERGE, WAITING, loop_of
@@ -124,6 +124,32 @@ class Forge:
     def close_pull_request(self, repo: str, index: int) -> None:
         self.prs[index]["state"] = "closed"
 
+    # what a new project's checks read (D4)
+    protected = False
+
+    def protect(self) -> None:
+        """Protection as the server enforces it: pushes to main refused by a
+        hook; merging needs an approval nobody here gives."""
+        hook = self.bare / "hooks" / "pre-receive"
+        hook.write_text(
+            "#!/bin/sh\nwhile read old new ref; do\n"
+            '  [ "$ref" = refs/heads/main ] && echo "main is protected" && exit 1\n'
+            "done\nexit 0\n"
+        )
+        hook.chmod(0o755)
+        self.protected = True
+
+    def repository(self, repo: str) -> dict[str, Any]:
+        return {"permissions": {"push": True}}
+
+    def branch(self, repo: str, name: str) -> dict[str, Any]:
+        return {"protected": self.protected, "user_can_push": not self.protected}
+
+    def merge_pull_request(self, repo: str, index: int) -> None:
+        if self.protected:
+            raise GiteaError("gitea POST merge returned 405: approvals needed")
+        self.merge(index)
+
     # what the operator does in Gitea
     def merge(self, n: int) -> None:
         head = f"refs/heads/{self.prs[n]['head']}"