[kaxil]

AgentOperator(code_mode=True) did one thing: it appended a bare CodeMode() from pydantic-ai-harness to the agent's capabilities. Since capabilities= became a first-class argument (#73984), that is one line in the Dag file, so this removes the flag and documents the capability instead:

from pydantic_ai_harness import CodeMode

AgentOperator(..., capabilities=[CodeMode(max_tool_calls=200)])

The flag also hid every CodeMode argument, and one of them matters in practice. max_tool_calls caps the nested tool calls a single run_code snippet can make, and its default of 100 is low for an agent that fans out over a list. In a run that classified 167 issue comments (one listing call, 80 comment fetches, 167 classifier calls), code_mode=True hit the cap and the model had to split its work across snippets: 11 model requests and about 39k input tokens, against 7 requests and about 20k tokens with CodeMode(max_tool_calls=400). A snippet that hits the cap also fails after the calls it already made, so their results are lost.

Code mode is documented as experimental, so this is a removal rather than a deprecation. The changelog note covers the migration: replace code_mode=True with capabilities=[CodeMode()], and move any agent_params["capabilities"] into capabilities= too, since the two cannot be combined.

The code-mode extra's floor goes from pydantic-ai-harness>=0.3.0 to >=0.24.0, the first release with max_tool_calls; the docs and example now use it, and uv.lock already resolves 0.34.0.

Two things change for users beyond the argument:

• The harness is imported when the Dag file is parsed, not when the task runs, so the code-mode extra is needed wherever Dag files are parsed. The old flag existed partly to avoid this. The import measured at about 0.02 s; code_mode.rst says so and suggests keeping code mode agents in their own Dag file.
• The docs said a tool that needs approval fails the task under code mode. That was wrong. pydantic-ai-harness catches ApprovalRequired inside run_code and returns it to the model as a retry, so the gated call does not run and the task can still succeed. code_mode.rst, tool_approval.rst and the operator docstring now say that, and how to keep such a tool out of run_code with CodeMode(tools=[...]).

The durable and tool-approval guards already recognised a CodeMode capability (including one nested in a CombinedCapability or PrefixTools), so they need no change; only the flag's branches go.

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