[FEATURE]: Add expanded hook events to the plugin system to enable more powerful plugin capabilities.

[reactive-end]

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

Problem

The current OpenCode plugin system lacks many useful hook events that would allow plugins to intercept and customize agent behavior at key points. This makes it difficult to build powerful plugins that can:

• Monitor session lifecycle (start/end)
• Intercept tool execution (modify arguments, log results)
• React to agent stopping events
• Handle permission requests
• Participate in session compaction

Proposed Solution

Expand the hook events system with new lifecycle hooks:

• session.start / session.end - Session lifecycle
• stop - Agent stop event
• preToolUse / postToolUse - Tool execution interception
• permission.request - Permission request event
• preCompact / postCompact - Session compaction events
  All hooks include functional triggers in the codebase.

Files Changed

• packages/plugin/src/index.ts - Hook type definitions
• packages/opencode/src/session/index.ts - session.start/end triggers
• packages/opencode/src/session/processor.ts - stop trigger
• packages/opencode/src/session/prompt.ts - preToolUse/postToolUse triggers
• packages/opencode/src/session/compaction.ts - preCompact/postCompact triggers
• packages/opencode/src/permission/index.ts - permission.request trigger

[github-actions]

This issue doesn't fully meet our contributing guidelines.

What needs to be fixed:

• Feature request titles must start with [FEATURE]: — please rename to: [FEATURE]: Add expanded hook events to the plugin system to enable more powerful plugin capabilities

Please edit this issue to address the above within 2 hours, or it will be automatically closed.

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This issue might be a duplicate of existing issues. Please check:

• Native Claude Code hooks compatibility (PreToolUse, PostToolUse, Stop) #12472: Native Claude Code hooks compatibility (PreToolUse, PostToolUse, Stop) — directly covers preToolUse/postToolUse/stop hooks
• [FEATURE]: SessionStart hook for session lifecycle events #5409: SessionStart hook for session lifecycle events — directly covers session.start/session.end
• [FEATURE]:Add pre-compaction hook for session save/export #14164: Add pre-compaction hook for session save/export — directly covers preCompact/postCompact
• [FEATURE]: add session.stopping plugin hook to allow re-entering the agent loop #16626: add session.stopping plugin hook — covers the stop agent event
• [FEATURE]: Wire the permission.ask plugin hook #19469: Wire the permission.ask plugin hook — covers permission.request

This request appears to bundle several hooks that have already been individually requested. Please review the above issues and consider whether this should be closed in favor of the existing ones (or link to them).

If you believe this was flagged incorrectly, please let a maintainer know.

[github-actions]

Thanks for updating the issue! The title now correctly starts with [FEATURE]: and the issue meets our contributing guidelines. We appreciate the detailed proposal.

[xbjpku]

This is partially addressed by #23650 — a minimal session.turn.completed event (+9 lines, 2 files). It enables post-turn plugins like ScarletWitch, a filesystem sandbox that shows a COW review dialog after each turn. Happy to adjust based on feedback.