feat: give codex system prompt via personality

[k11kirky]

Problem

The Codex adapter was not receiving custom instructions/system prompts, and token usage tracking was incomplete, limiting its ability to follow user-specific guidance and provide accurate usage metrics during task execution.

Changes

• Added instructions parameter to TaskExecutionOptions and CodexProcessOptions interfaces
• Modified the Codex spawn logic to pass instructions as a configuration parameter with proper escaping for backslashes and quotes
• Moved system prompt building earlier in the agent service to make it available during initial connection setup
• Enhanced token usage tracking in the Codex adapter to accumulate usage across prompts and emit turn completion notifications
• Updated the Codex client to track per-message token usage including cached read/write tokens
• Added proper usage accumulation in session state for comprehensive token tracking

How did you test this?

I wont lie, i didnt test this more than a quick test prompt. trust the agents bro

[k11kirky]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• feat: Harden CodexAcpAgent session state and permission handling #1487
• feat: give codex permissions support #1483
• feat: give codex system prompt via personality #1482 👈 (View in Graphite)
• feat: clean up session reloadin #1481
• feat: update codex adapter and migrate to base acp prxy for agent #1480
• feat: codex 5.4 default and pass to model #1479
• main

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