fix(lint): satisfy ruff on argus patches after upstream merge

Upstream's lint workflow caught three issues in our patches that the
post-merge tree exposed:

  - prompt.py: two lines in the <file_editing> block exceeded
    line-length=240 (E501). Tightened the prose; same meaning, both
    lines now 224.
  - test_postgres_aprune.py: ruff I001 wanted the deerflow import
    grouped with other imports, but it has to live below
    pytest.importorskip(). Already had # noqa: E402 for that reason;
    extended to E402, I001.
  - factory.py + test_postgres_aprune.py: ruff format wanted the
    weakref dict declaration and two set comprehensions on single
    lines. Applied uvx ruff format.

No behavior change.

Author: Nichol4s

backend/packages/harness/deerflow/agents/lead_agent/prompt.py

@@ -452,14 +452,14 @@ def _build_subagent_section(max_concurrent: int) -> str:
 - Final deliverables must be copied to `/mnt/user-data/outputs` and presented using `present_files` tool
 {acp_section}
 <file_editing>
-**Prefer targeted edits over full rewrites.** When modifying a file you wrote earlier in this conversation, the cost of rewriting is real: every byte of the rewritten file has to be re-emitted as model output and lives in conversation history forever. A 5-line fix in a 500-line file should be 5 lines, not 500.
+**Prefer targeted edits over full rewrites.** Rewriting a file you wrote earlier is expensive: every byte gets re-emitted and lives in conversation history forever. A 5-line fix in a 500-line file should be 5 lines, not 500.
 
 **Tool ordering when changing files:**
 1. `str_replace` — for targeted modifications. Use this whenever you can describe the change as "replace X with Y" in an existing file. Faster than rewriting because only the diff goes through the LLM.
 2. `write_file` — for *new* files, or when the change covers more than ~80% of the file's contents.
 3. `bash` heredocs (`cat <<EOF > file`) — avoid for any file you might edit later. The full content gets baked into conversation history. Reserve heredocs for one-off scripts the agent itself will execute and discard.
 
-**Before editing a file you wrote earlier in the same conversation, call `read_file` first.** Don't rely on memory of what you wrote — context can drift. `read_file` is cheap; `str_replace` failing because of a stale "expected old content" is expensive.
+**Before editing a file you wrote earlier in the same conversation, call `read_file` first.** Don't rely on memory — context drifts. `read_file` is cheap; `str_replace` failing on stale "expected old content" is expensive.
 
 **For deliverables in `/mnt/user-data/outputs`:** write the file once with `write_file`. If you find a bug after writing, use `str_replace` to fix in place. Do not re-run a HEREDOC `cat > ...` to rewrite the whole file.
 </file_editing>

backend/packages/harness/deerflow/models/factory.py

@@ -29,9 +29,7 @@
 #
 # WeakValueDictionary so the client is GC'd when its loop is GC'd; no leak
 # across long-lived processes that handle thousands of short-lived loops.
-_PER_LOOP_HTTPX_CLIENTS: "weakref.WeakValueDictionary[int, httpx.AsyncClient]" = (
-    weakref.WeakValueDictionary()
-)
+_PER_LOOP_HTTPX_CLIENTS: "weakref.WeakValueDictionary[int, httpx.AsyncClient]" = weakref.WeakValueDictionary()
 
 
 def _httpx_client_for_current_loop() -> httpx.AsyncClient | None:

backend/tests/test_postgres_aprune.py

@@ -23,7 +23,7 @@
 # checkpointer at image build time, so the test runs in our CI.
 pytest.importorskip("langgraph.checkpoint.postgres.aio")
 
-from deerflow.agents.checkpointer import _postgres_aprune  # noqa: E402
+from deerflow.agents.checkpointer import _postgres_aprune  # noqa: E402, I001
 
 
 # ---------------------------------------------------------------------------
@@ -101,10 +101,7 @@ async def test_keep_latest_issues_two_deletes(self):
         await _postgres_aprune._aprune(saver, ["t1", "t2"], strategy="keep_latest")
 
         assert len(saver.cursor.calls) == 2
-        tables_touched = [
-            "checkpoints" if "FROM checkpoints" in sql else "checkpoint_writes"
-            for sql, _ in saver.cursor.calls
-        ]
+        tables_touched = ["checkpoints" if "FROM checkpoints" in sql else "checkpoint_writes" for sql, _ in saver.cursor.calls]
         assert set(tables_touched) == {"checkpoints", "checkpoint_writes"}
         # Blobs must not be touched
         for sql, _ in saver.cursor.calls:
@@ -119,12 +116,7 @@ async def test_delete_all_touches_all_three_tables(self):
         await _postgres_aprune._aprune(saver, ["t1"], strategy="delete_all")
 
         assert len(saver.cursor.calls) == 3
-        tables = {
-            "checkpoints" if "FROM checkpoints " in sql else
-            "checkpoint_blobs" if "FROM checkpoint_blobs " in sql else
-            "checkpoint_writes"
-            for sql, _ in saver.cursor.calls
-        }
+        tables = {"checkpoints" if "FROM checkpoints " in sql else "checkpoint_blobs" if "FROM checkpoint_blobs " in sql else "checkpoint_writes" for sql, _ in saver.cursor.calls}
         assert tables == {"checkpoints", "checkpoint_blobs", "checkpoint_writes"}
 
     async def test_unknown_strategy_raises(self):