agentmemory-capture

 agentmemory for OpenCode

<strong>Your OpenCode agents remember everything. No more re-explaining.</strong>

_{Persistent cross-session memory via agentmemory — 95.2% retrieval accuracy on LongMemEval-S.}

---

Quick start

1. Start the agentmemory server

npx @agentmemory/agentmemory

The server starts on http://localhost:3111.

2. Configure the MCP server

Add to ~/.config/opencode/opencode.json or your project's .opencode/opencode.json:

{
  "mcp": {
    "agentmemory": {
      "type": "local",
      "command": ["npx", "-y", "@agentmemory/mcp"],
      "enabled": true
    }
  }
}

3. Install the plugin

Add to ~/.config/opencode/opencode.json:

{
  "plugin": ["./plugins/agentmemory-capture.ts"]
}

Copy the plugin file from this repo:

mkdir -p ~/.config/opencode/plugins
cp plugin/opencode/agentmemory-capture.ts ~/.config/opencode/plugins/

4. Add the slash commands

Copy the commands into your project or global .opencode/commands/ directory:

mkdir -p ~/.config/opencode/commands
cp plugin/opencode/commands/recall.md ~/.config/opencode/commands/
cp plugin/opencode/commands/remember.md ~/.config/opencode/commands/

Restart OpenCode or open a new session. The plugin auto-captures everything.

What gets captured

Session lifecycle

Event	Hook	agentmemory API
Session start	session.created	POST /session/start
Idle → summarize	session.idle + session.status (idle)	POST /summarize
Status transitions	session.status (idle/busy/retry)	POST /observe
Compaction	session.compacted	POST /summarize + POST /observe
Metadata updates	session.updated	POST /observe
Code change tracking	session.diff	POST /observe
Session delete	session.deleted	POST /session/end
Session error	session.error	POST /observe

Messages & prompts

Event	Hook	agentmemory API
User prompt (rich)	chat.message	POST /observe
User prompt metadata	message.updated (user)	POST /observe
Assistant response	message.updated (assistant)	POST /observe
Message removed (undo)	message.removed	POST /observe

Parts & steps

Event	Hook	agentmemory API
Subagent start	message.part.updated (subtask)	POST /observe
Tool completed	message.part.updated (tool completed)	POST /observe
Tool error	message.part.updated (tool error)	POST /observe
Step finish (cost/tokens)	message.part.updated (step-finish)	POST /observe
Reasoning trace	message.part.updated (reasoning)	POST /observe
Patch applied	message.part.updated (patch)	POST /observe
Auto/manual compaction	message.part.updated (compaction)	POST /observe
Agent selection	message.part.updated (agent)	POST /observe
API retry	message.part.updated (retry)	POST /observe

File enrichment pipeline

Event	Hook	agentmemory API
File tool params	tool.execute.before → stash paths	—
File edited	file.edited → stash paths	—
File part attached	message.part.updated (file) → stash paths	—
Enrichment inject	experimental.chat.system.transform	POST /enrich → output.system[]
Memory context inject	experimental.chat.system.transform	POST /context → output.system[]

Permissions

Event	Hook	agentmemory API
Permission prompt	permission.updated	POST /observe
Permission reply	permission.replied	POST /observe

Tasks & commands

Event	Hook	agentmemory API
Task tracking (w/ priority)	todo.updated	POST /observe
Command executed	command.executed	POST /observe

Model & config

Event	Hook	agentmemory API
LLM parameters	chat.params	POST /observe
Config loaded	config	POST /observe
Compaction (WIP)	experimental.session.compacting	POST /context → output.context[]

File enrichment + memory injection (two-layer pipeline)

experimental.chat.system.transform fires before every LLM call and injects two layers of context:

1. Memory context (once per session): calls /agentmemory/context and injects project profile, recent session summaries, and important past observations into the system prompt. This is the OpenCode equivalent of Claude's MEMORY.md bridge — instead of syncing to a markdown file, context is injected directly into the system prompt.

2. File enrichment (every turn with stashed files): calls /agentmemory/enrich with files stashed by tool.execute.before, file.edited, and message.part.updated (file parts). File-specific context (past observations, related bugs, semantic search) is injected into the system prompt.

System prompt = [OpenCode instructions] + [memory context] + [file enrichment] + [user message]
                                        ^                 ^
                               first turn only         every file-touching turn

Differences from Claude's PreToolUse:

Dimension	Claude (PreToolUse)	OpenCode (two-hop pipeline)
Injection mechanism	stdout → context window	output.system[] → system prompt
Timing	Same turn (parallel with tool)	Next turn (before next LLM call)
File set	Per-tool (immediate)	Batched (all files since last enrichment)
Coverage	Edit/Write/Read/Glob/Grep only	Edit/Write/Read/Glob/Grep only
What gets injected	<agentmemory-file-context> + bug memories	Identical /enrich response

MEMORY.md vs AGENTS.md: how context flows

Claude Code and OpenCode take fundamentally different approaches to injecting memory context into the agent's system prompt.

Claude Code: file-backed bridge (two-hop)

agentmemory  ──write──▶  MEMORY.md  ──read──▶  Claude system prompt

• The claude-bridge/sync endpoint serializes agentmemory observations into a MEMORY.md file in the project root
• Claude Code reads MEMORY.md on session start and prepends it to the system prompt
• Sync is periodic — sessions only get fresh context when the bridge last ran (session end, pre-compact)
• Coupling: memory data lives in a git-trackable file, visible to CI, team members, and other tools

OpenCode: direct injection (one-hop)

agentmemory  ──push──▶  OpenCode system prompt

• experimental.chat.system.transform calls /context at runtime and pushes the response directly into output.system[]
• Always current — context is fetched at session start (once) and before file-touching turns (per-batch)
• No file intermediary — no stale copies, no merge conflicts, no disk I/O
• AGENTS.md is a static instruction file for project conventions, coding standards, and tool guidance — agentmemory does not read or write it

Tradeoffs

Dimension	Claude (MEMORY.md bridge)	OpenCode (direct injection)
Freshness	Stale between syncs	Always current (fetched at call time)
Visibility	Human-readable file in repo	In-memory injection only
Simplicity	Two moving parts (bridge + file)	One step (API → system prompt)
Team sharing	File is git-trackable, CI-friendly	Memory shared via agentmemory server API
Integration	Any tool can read MEMORY.md	Requires OpenCode plugin SDK

Why OpenCode goes direct

agentmemory already persists everything in SQLite (data/state_store.db). Adding an intermediate MEMORY.md file would duplicate data, introduce sync lag, and require the model to re-parse structured context from markdown. Direct injection delivers the same data with lower latency and zero staleness — the agent always sees what agentmemory knows right now.

Slash commands

• /recall <query> — Search past observations and lessons
• /remember <text> — Save an insight to long-term memory

Session instruction injection

Agentmemory usage instructions are injected into the system prompt on the first turn of every session via experimental.chat.system.transform (alongside memory context from /context). This is functionally equivalent to Claude Code's skills mechanism — the agent learns which agentmemory_memory_* tools to use and when, without needing separate skill invocations.

What's not covered (vs Claude Code plugin)

Claude feature	Reason
SubagentStop	OpenCode's SubtaskPart type has no completion/result fields; subtask lifecycle ends are not exposed as distinct events in the OpenCode SDK
TaskCompleted	No team/teammate concept in OpenCode; todo.updated captures task state changes as a partial equivalent
Stop	session.compacted event handler exists; experimental.session.compacting injection hook defined in SDK but Go binary (v1.14.41) doesn't wire it — will auto-activate when upstream implements it
Skills (remember/recall/forget/session-history)	Covered by injected system instructions via experimental.chat.system.transform — agent receives usage guidance on first turn
Consolidation pipeline (crystals/auto + consolidate-pipeline)	Now called on session.deleted — mirrors Claude's CONSOLIDATION_ENABLED=true behavior
Claude MEMORY.md bridge	OpenCode-specific; OpenCode uses its own AGENTS.md mechanism, not Claude's MEMORY.md

All other Claude Code hooks have direct or pipeline equivalents in this plugin. 12 of 12 Claude hook types covered.