refactor: dedupe `_dump` helper, collapse retry-policy plumbing, scrub test scars

Tools:
- Add a single ``dump_tool_result`` helper in ``tools/_decorator.py``
  and remove the eight identical ``_dump`` definitions from
  ``proxy/tools.py``, ``file_edit/tools.py``, ``python/tool.py``,
  ``terminal/tool.py``, ``todo/tools.py``, ``browser/tool.py``,
  ``notes/tools.py``, ``agents_graph/tools.py``. Imports trimmed.
  Net -50 LoC across the tool modules.

run_config_factory:
- Inline the four retry-policy plumbing pieces
  (``_RETRYABLE_HTTP_STATUSES``, ``_DEFAULT_MAX_RETRIES``,
  ``_DEFAULT_BACKOFF``, ``_default_retry_policy()``) into a single
  module-level ``_DEFAULT_RETRY`` ``ModelRetrySettings`` literal. The
  inputs were never overridden and the helper had one caller.

Tests:
- Drop migration scars from ``tests/test_run_config_factory.py``
  (``Phase 1`` / ``C1`` / ``C11`` / ``C21`` / ``HARNESS_WIKI`` / ``AUDIT``
  references). Replace the ``_RETRYABLE_HTTP_STATUSES``-touching test
  with a ``retry.policy is not None`` smoke check now that the constant
  has been inlined.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

strix/tools/proxy/tools.py

@@ -10,19 +10,14 @@ scope_rules, list_sitemap, view_sitemap_entry.
 
 from __future__ import annotations
 
-import json
 from typing import Any, Literal
 
 from agents import RunContextWrapper
 
-from strix.tools._decorator import strix_tool
+from strix.tools._decorator import dump_tool_result, strix_tool
 from strix.tools._sandbox_dispatch import post_to_sandbox
 
 
-def _dump(result: dict[str, Any]) -> str:
-    return json.dumps(result, ensure_ascii=False, default=str)
-
-
 RequestPart = Literal["request", "response"]
 SortBy = Literal[
     "timestamp",
@@ -80,7 +75,7 @@ async def list_requests(
         sort_order: ``asc`` or ``desc``.
         scope_id: Restrict to a scope (managed via ``scope_rules``).
     """
-    return _dump(
+    return dump_tool_result(
         await post_to_sandbox(
             ctx,
             "list_requests",
@@ -131,7 +126,7 @@ async def view_request(
         page: 1-indexed page number (only when no ``search_pattern``).
         page_size: Lines per page.
     """
-    return _dump(
+    return dump_tool_result(
         await post_to_sandbox(
             ctx,
             "view_request",
@@ -172,7 +167,7 @@ async def send_request(
         body: Optional request body string.
         timeout: Per-request timeout in seconds (default 30).
     """
-    return _dump(
+    return dump_tool_result(
         await post_to_sandbox(
             ctx,
             "send_request",
@@ -221,7 +216,7 @@ async def repeat_request(
             - ``body`` — replace the body string entirely.
             - ``cookies`` — dict of cookies to add/update.
     """
-    return _dump(
+    return dump_tool_result(
         await post_to_sandbox(
             ctx,
             "repeat_request",
@@ -280,7 +275,7 @@ async def scope_rules(
         scope_id: Required for ``get`` / ``update`` / ``delete``.
         scope_name: Required for ``create`` / ``update``.
     """
-    return _dump(
+    return dump_tool_result(
         await post_to_sandbox(
             ctx,
             "scope_rules",
@@ -328,7 +323,7 @@ async def list_sitemap(
         depth: ``"DIRECT"`` (immediate children) or ``"ALL"`` (recursive).
         page: 1-indexed page (30 entries/page).
     """
-    return _dump(
+    return dump_tool_result(
         await post_to_sandbox(
             ctx,
             "list_sitemap",
@@ -353,6 +348,6 @@ async def view_sitemap_entry(ctx: RunContextWrapper, entry_id: str) -> str:
     Args:
         entry_id: Sitemap entry id from ``list_sitemap``.
     """
-    return _dump(
+    return dump_tool_result(
         await post_to_sandbox(ctx, "view_sitemap_entry", {"entry_id": entry_id}),
     )