[FEATURE]: Enhance Input/Output Structure of "experimental.chat.system.transform" and "experimental.chat.messages.transform" Hooks for Better Usability #27364

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Describe the enhancement you want to request

Version

Current version: 1.14.48

Environment

Pure code logic, environment-agnostic.

Problem Description

While developing an OpenCode plugin, I discovered the experimental.chat.system.transform and experimental.chat.messages.transform hooks.

I was excited because they seemed perfect for fine-tuning system prompts and message history for each prompt. However, I quickly realized they didn't meet my expectations due to a shared limitation: the Input and Output data structures are insufficient. See the details below:

experimental.chat.system.transform

Parameters:

• input: { sessionID?: string; model: Model }
• output: { system: string[] }

Callers:

• Caller 1: session/llm.ts:118-121 (Normal LLM call)
• Caller 2: agent/agent.ts:451 (Agent generation, without session context)

experimental.chat.messages.transform

Parameters:

• input: {}
• output: { messages: { info: Message; parts: Part[] }[] }

Callers:

• Caller 1: session/prompt.ts:1587 (Normal LLM call)
• Caller 2: session/compaction.ts:411 (During compaction)

Common Issue

sessionID and messageID are important pieces of data for determining whether and how we should process the system prompt and message history for the current prompt. I suggest adding them to the input structure. (Of course, due to the differences in callers, it is acceptable for these fields to be optional/undefined in certain cases.)

Improvement Suggestions

experimental.chat.system.transform

Parameters:

• input: { sessionID?: string; messageID?: string; model: Model }
• output: { system: string[] }

experimental.chat.messages.transform

Parameters:

• input: { sessionID?: string; messageID?: string; model: Model }
• output: { messages: { info: Message; parts: Part[] }[] }

Feasibility Assessment

Since these are experimental hooks, the impact of the change is minimal. The proposed changes are backward compatible and require very little code modification, making them highly feasible.