feat: apply search release plans atomically (Closes #817)

src/gitea_proxy.py

@@ -1969,6 +1969,58 @@ async def update_assigned_issue_milestone(
     }
 
 
+async def update_assigned_issue_release_plan(
+    repository: str, number: int, milestone_id: int, due_date: str | None
+) -> dict:
+    path = f"repos/{repository}/issues/{number}"
+    login, issue = await _current_login_and_target(path)
+    if (
+        issue.get("state") != "open"
+        or isinstance(issue.get("pull_request"), dict)
+        or not _login_in_users(login, issue.get("assignees"))
+    ):
+        raise IssueNotAvailableError("assigned issue not found")
+
+    selected = next(
+        (item for item in await repo_milestones(repository) if item["id"] == milestone_id),
+        None,
+    )
+    if selected is None:
+        raise ValueError("Unknown open repository milestone")
+
+    payload: dict = {"milestone": milestone_id}
+    if due_date is not None:
+        payload["due_date"] = due_date
+    response = await _get_client().patch(
+        f"/api/v1/{path}", headers=_auth(), json=payload
+    )
+    response.raise_for_status()
+    confirmed = response.json()
+    milestone_value = confirmed.get("milestone") if isinstance(confirmed, dict) else None
+    normalized = (
+        {"id": milestone_value["id"], "title": milestone_value["title"]}
+        if isinstance(milestone_value, dict)
+        and isinstance(milestone_value.get("id"), int)
+        and isinstance(milestone_value.get("title"), str)
+        else None
+    )
+    expected_due_date = due_date if due_date is not None else issue.get("due_date")
+    if (
+        not isinstance(confirmed, dict)
+        or confirmed.get("number") != number
+        or normalized != selected
+        or confirmed.get("due_date") != expected_due_date
+    ):
+        raise ValueError("Gitea did not confirm the issue release plan")
+    return {
+        "repository": repository,
+        "number": number,
+        "state": confirmed.get("state", "open"),
+        "milestone": normalized,
+        "due_date": confirmed.get("due_date"),
+    }
+
+
 async def issue_conversation_page(
     repository: str,
     number: int,

src/main.py

@@ -763,6 +763,15 @@ class IssueMilestoneUpdate(BaseModel):
     milestone_id: PositiveInt | None = None
 
 
+class IssueReleasePlanUpdate(BaseModel):
+    milestone_id: PositiveInt
+    due_date: str | None = Field(
+        default=None,
+        pattern=r"^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}Z$",
+        max_length=20,
+    )
+
+
 class IssueHandoff(BaseModel):
     recipient: str = Field(
         min_length=1, max_length=255, pattern=r"^[A-Za-z0-9_.-]+$"
@@ -4374,6 +4383,40 @@ async def update_assigned_issue_milestone(
     return JSONResponse(result)
 
 
+@app.patch("/api/v1/repos/{owner}/{repo}/issues/{number}/release-plan")
+async def update_assigned_issue_release_plan(
+    update: IssueReleasePlanUpdate,
+    owner: str,
+    repo: str,
+    number: int = PathParam(gt=0),
+):
+    repository = f"{owner}/{repo}"
+    try:
+        result = await asyncio.wait_for(
+            gitea_proxy.update_assigned_issue_release_plan(
+                repository, number, update.milestone_id, update.due_date
+            ),
+            timeout=ISSUE_ACTION_TIMEOUT_SECONDS,
+        )
+    except gitea_proxy.IssueNotAvailableError:
+        raise HTTPException(status_code=404, detail="Assigned issue not found")
+    except ValueError as exc:
+        if str(exc) == "Unknown open repository milestone":
+            raise HTTPException(status_code=422, detail=str(exc))
+        return JSONResponse(
+            {"error": "The release plan could not be confirmed. Your selection is safe; please retry."},
+            status_code=503,
+            headers={"Retry-After": "1"},
+        )
+    except Exception:
+        return JSONResponse(
+            {"error": "The release plan could not be updated. Your selection is safe; please retry."},
+            status_code=503,
+            headers={"Retry-After": "1"},
+        )
+    return JSONResponse(result)
+
+
 @app.get("/api/v1/repos/{owner}/{repo}/milestones")
 async def repository_milestones(owner: str, repo: str):
     repository = f"{owner}/{repo}"