feat(command): add noReply flag to skip LLM dispatch

[Svtter]

Issue for this PR

Related to #28292, #5305, #26022. Builds on the schema approach from #27521.

Type of change

• Bug fix
• New feature
• Refactor
• Other

What does this PR do?

Adds a noReply boolean flag to the command schema. When true, the LLM round-trip is skipped entirely and hook-modified parts are written as a completed assistant message so they render immediately in the TUI.

Problem: Plugins like opencode-review register toggle commands (/review:auto on/off) that just flip a boolean. Currently this requires a full LLM agent round-trip — wasting tokens and adding latency for an instant operation. The command.execute.before hook can intercept the command but cannot skip the LLM call.

Changes:

File	Change
config/command.ts	Add noReply to command config schema
command/index.ts	Add noReply to command registry schema + pass through
session/prompt.ts	Pass noReply from command() to prompt(); when set, create assistant message with parts directly (no LLM)
test/session/prompt.test.ts	New test: noReply command skips LLM and creates assistant message with parts

Differences from PR #27521: That PR added the noReply schema but when it short-circuited the LLM, the command's parts silently disappeared. This PR also creates a visible assistant message in the TUI so the user sees the result.

Usage — command config (.opencode/commands/test.md):

---
noReply: true
description: instant command
---
Result: $ARGUMENTS

Or via plugin config hook:

openCodeConfig.command["my-cmd"] = {
  template: "placeholder",
  noReply: true,
}

Combined with command.execute.before hook:

"command.execute.before": async (input, output) => {
  if (input.command !== "my-cmd") return
  output.parts = [{ type: "text", text: "Done!" }]
}

How did you verify your code works?

• bun run typecheck passes (15/15 packages)
• New unit test passes: noReply command skips LLM and creates assistant message with parts
• 52/54 existing tests pass (2 pre-existing flaky cancel race tests)
• Manual test: opencode run --command test -- "hello" exits instantly, no LLM call
• Integration test with opencode-review plugin: /review:auto off skips LLM, toggles state via hook

Screenshots / recordings

N/A (session/prompt behavior change, no TUI layout change)

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

🤖 Generated with Claude Code

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Related PR Found:

PR #27521: feat(command): add noReply flag to skip LLM dispatch for display-only commands
#27521

Why they're related:
PR #27521 is an earlier attempt that introduced the noReply schema approach, but PR #28763 (the current PR) builds upon and improves it by solving the missing piece: ensuring command parts appear as a visible assistant message in the TUI when noReply short-circuits the LLM (instead of silently disappearing). The current PR explicitly acknowledges this relationship in its "Differences from PR #27521" section.

[github-actions]

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