[codex] Fix chmod batch agent identity contract

[shangguanxuan633-lab]

Background

PR #414 changed dws pat chmod batch plan/grant payloads to include agentCode. Shell verification against the real batch plan endpoint showed that the batch service rejects this as a forged identity field:

PAT_FORGED_IDENTITY_FIELD: PAT batch identity field 'agentCode' must be derived by gateway.

The correct contract is: DINGTALK_DWS_AGENTCODE is picked up by the CLI and made visible to the MCP call environment/header path; pat.batch_plan and pat.batch_grant must not carry agentCode in the tool arguments.

Changes

• Remove agentCode from pat.batch_plan / pat.batch_grant arguments.
• Keep canonical/legacy single-grant fallback behavior unchanged.
• Extend chmod tests to assert batch plan/grant calls see the env value while their args omit the identity field.

Shell smoke

Built the PR binary locally as /tmp/dws-chmod-agentcode and checked:

• env DINGTALK_DWS_AGENTCODE=qoderwork /tmp/dws-chmod-agentcode --dry-run pat chmod aitable.record:read calendar.event:read --grant-type once prints AgentCode: qoderwork.
• env -u DINGTALK_DWS_AGENTCODE /tmp/dws-chmod-agentcode --dry-run pat chmod aitable.record:read calendar.event:read --grant-type once prints AgentCode: (server default).
• env DINGTALK_DWS_AGENTCODE=envval /tmp/dws-chmod-agentcode --dry-run pat chmod aitable.record:read calendar.event:read --grant-type once --agentCode flagval prints AgentCode: flagval.
• env DINGTALK_DWS_AGENTCODE=qoderwork /tmp/dws-chmod-agentcode --dry-run -f json pat chmod --products calendar,aitable --grant-type once succeeds; summarized response: success=true agentCode=dingmbw5n9ktkkbbjv3g selected=0 skipped=32.

Verification

• go test ./internal/pat
• go test ./internal/app