submit and author resubmits: the commit must be a hash git knows (checked in the author's workdir or the Logbook checkout) and is stored in full; HEAD, placeholders and unknown hashes are refused

harbor/flow.py

@@ -39,6 +39,29 @@ def _git(workdir, *args):
 
 
 class FlowMixin:
+    def resolve_commit(self, agent, commit):
+        """The full hash of a commit an item names, checked in agent's workdir (or the Logbook's decomp checkout).
+        A placeholder ('HEAD', 'PLACEHOLDER') or a hash git does not know is refused; without any git checkout to
+        ask, the value is kept as given."""
+        if not commit:
+            return commit
+        commit = str(commit).strip()
+        spec = next((a for a in self.project.agents if a["name"] == agent), {})
+        places = [spec.get("workdir"), (self.project.logbook or {}).get("decomp")]
+        repos = [p for p in places if p and (Path(p) / ".git").exists()]
+        if not repos:
+            return commit
+        if not re.fullmatch(r"[0-9a-fA-F]{7,40}", commit):
+            raise HarborError(f"commit {commit!r} is not a hash: give the commit's hash (git rev-parse HEAD), "
+                              "not a branch name, HEAD or a placeholder")
+        for repo in repos:
+            try:
+                return _git(repo, "rev-parse", "--verify", "--quiet", f"{commit}^{{commit}}").strip()
+            except (RuntimeError, subprocess.TimeoutExpired):
+                continue
+        raise HarborError(f"commit {commit} is not in the repository: commit your work first and give the hash "
+                          "git rev-parse HEAD prints")
+
     def worktree_change(self, agent):
         """(mtime, path) of the most recently modified uncommitted file in agent's worktree, or None."""
         spec = next((a for a in self.project.agents if a["name"] == agent), {})