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/src/nisse_dev/loop/milestones.py

@@ -7,7 +7,9 @@ Publishing is idempotent under an intent (L8): an open PR for the branch is
 adopted, and a PR the operator closed is an answer, never reopened.
 """
 
+import contextlib
 import time
+import uuid
 from dataclasses import dataclass
 from typing import Literal
 
@@ -159,6 +161,79 @@ class Milestones:
         if git.remote_sha(self._remote, parked, credential=self._credential):
             git.delete_remote_branch(self._remote, parked, credential=self._credential)
 
+    # -- a new project's checks (D1, D4) -----------------------------------------
+
+    def verify_access(self, account: str) -> list[str]:
+        """What the operator provided, checked rather than assumed: the
+        agent may push a branch with its push credential, may not push to
+        the default branch, and may not merge its own PR without approval.
+        A throwaway branch with an empty commit carries the checks; its PR
+        is closed and the branch deleted. Returns what failed."""
+        git, base, failures = self._git, self._base, []
+        try:
+            repo = self._gitea.repository(self._repo)
+            if not (repo.get("permissions") or {}).get("push"):
+                failures.append(f"{account} isn't a collaborator with write access")
+            branch = self._gitea.branch(self._repo, base)
+            if not branch.get("protected") or branch.get("user_can_push"):
+                failures.append(f"{base} isn't protected against my pushes")
+        except GiteaError as exc:
+            return [f"I can't see the repository {self._repo}: {exc}"]
+        check = f"nisse-check-{uuid.uuid4().hex[:6]}"
+        try:
+            git.fetch(credential=self._credential)
+            git.reset_to(check, f"origin/{base}")
+            git._git("commit", "-q", "--allow-empty", "-m", "nisse-dev: access check")
+        except GitError as exc:
+            return [*failures, f"the workspace isn't usable: {exc}"]
+        try:
+            git.push(self._remote, check, credential=self._credential)
+        except GitError as exc:
+            failures.append(f"my push credential can't push a branch: {exc}")
+            self._back_to_base(check)
+            return failures
+        try:
+            git.push(self._remote, base, credential=self._credential)
+            failures.append(
+                f"I could push to {base}, which protection should refuse; an "
+                f"empty commit, 'nisse-dev: access check', is on {base} now"
+            )
+        except GitError:
+            pass  # refused, as it should be
+        pr = None
+        try:
+            pr = self._gitea.open_pull_request(
+                self._repo,
+                head=check,
+                base=base,
+                title="nisse-dev access check (never merged)",
+                body="Checks that merging needs an approval; closed straight away.",
+            )
+            try:
+                self._gitea.merge_pull_request(self._repo, pr.number)
+                failures.append(
+                    f"I could merge my own PR #{pr.number} without an approval"
+                )
+            except GiteaError:
+                pass  # refused, as it should be
+        except GiteaError as exc:
+            failures.append(f"I couldn't open a PR to check merging: {exc}")
+        finally:
+            if pr is not None:
+                with contextlib.suppress(GiteaError):
+                    self._gitea.close_pull_request(self._repo, pr.number)
+            with contextlib.suppress(GitError):
+                git.delete_remote_branch(
+                    self._remote, check, credential=self._credential
+                )
+            self._back_to_base(check)
+        return failures
+
+    def _back_to_base(self, branch: str) -> None:
+        with contextlib.suppress(GitError):
+            self._git.reset_to(self._base, f"origin/{self._base}")
+            self._git._git("branch", "-q", "-D", branch)
+
     def _ahead_of_origin(self) -> bool:
         current = self._git.current_branch()
         try: