[Bug]: Plugin/user agents not injected into Sisyphus system prompt (customAgentSummaries type mismatch)

[cuipengfei]

Note: This issue was raised by the Sisyphus agent itself, based on code-level investigation during a deep-dive session into the OMO agent system.

Bug Description

Plugin agents (59 agents from 18 namespaces) and user-installed agents (~/.claude/agents/*.md) are not injected into the Sisyphus primary agent's system prompt. This is caused by a type mismatch in createBuiltinAgents() where the customAgentSummaries parameter receives an OpenCode client object instead of the expected agent summary array.

As a result, Sisyphus has zero awareness of any plugin or user agents at runtime. The only way to discover available agents is by intentionally triggering a resolver error to get the full agent list back in the error message.

Steps to Reproduce

1. Install oh-my-opencode with any plugin agents registered (e.g., pr-review-toolkit, error-diagnostics, etc.)
2. Start a session with the Sisyphus agent
3. Ask Sisyphus to list available agents or delegate to a plugin agent by name
4. Observe that Sisyphus has no knowledge of plugin/user agents in its system prompt

Alternatively, trace the code path:

1. In src/agents/dynamic-agent-prompt-builder.ts, the createBuiltinAgents() function accepts customAgentSummaries as the 8th parameter
2. In src/agents/custom-agent-summaries.ts, parseRegisteredAgentSummaries() checks Array.isArray(input)
3. The actual value passed is params.ctx.client (an OpenCode SDK client object)
4. Array.isArray(client) returns false → function returns [] → no agent summaries injected

Expected Behavior

All registered agents (builtin + plugin + user) should be summarized and injected into Sisyphus's system prompt, so it can intelligently route task() calls to the correct agent by name without trial-and-error.

Actual Behavior

parseRegisteredAgentSummaries() receives an OpenCode client object (not an array), silently returns an empty array, and no plugin/user agent information reaches the system prompt. There is no warning log for this silent failure.

Doctor Output

 oMoMoMoMo Doctor

 ⚠ 2 issues found:

1. Model override uses unavailable provider
   Provider(s) not found in OpenCode model cache: 4141, 4142
   Affects: model resolution

2. Comment checker unavailable
   Comment checker binary is not installed.
   Fix: Install @code-yeongyu/comment-checker
   Affects: comment-checker hook

Code Path Analysis

1. Agent Registration (works correctly)

agent-config-handler.ts merges agents from all sources:

• OMO builtin agents (10)
• User agents from ~/.claude/agents/*.md
• Project agents
• Plugin agents (59 from 18 plugin namespaces)

All 72+ agents are successfully registered in OpenCode's agent registry and are callable via task(subagent_type="agent-name").

2. System Prompt Injection (broken)

The createBuiltinAgents() function in dynamic-agent-prompt-builder.ts accepts a customAgentSummaries parameter (8th argument). This is intended to inject a summary of all available agents into the Sisyphus system prompt.

However, the caller passes params.ctx.client (the OpenCode SDK client object) instead of an array of agent summaries.

In custom-agent-summaries.ts:

export function parseRegisteredAgentSummaries(input: unknown): AgentSummary[] {
  if (!Array.isArray(input)) return []  // <-- client object hits this, returns []
  // ... parsing logic never reached
}

3. Impact on Agent Routing

Since Sisyphus has no agent summaries in its prompt:

• It cannot discover plugin agents by name
• task(subagent_type="some-plugin-agent") only works if the caller already knows the exact agent name
• The only discovery mechanism is triggering the resolver error, which dumps the full agent list in the error message

Secondary Finding: Model Routing for Plugin Agents

During this investigation, we also confirmed that plugin agents inherit their model from OpenCode's MRU (Most Recently Used) list in ~/.local/state/opencode/model.json, not from any explicit configuration. This is because:

1. OMO's agent-loader.ts does not parse the model field from agent frontmatter (AgentFrontmatter type has no model property)
2. The subagent-resolver.ts model resolution chain: AGENT_MODEL_REQUIREMENTS[key] (builtin only) → agentOverride?.model (none) → matchedAgent.model (none) → categoryModel (undefined)
3. When model is undefined, OpenCode falls back to Provider.defaultModel() → reads model.json MRU

This means plugin agents get whatever model the user last manually selected in the TUI, which may not be appropriate.

Configuration

Using default oh-my-opencode configuration with custom providers (4141, 4142) proxied through copilot-api.

Additional Context

• This issue was discovered through a systematic code-level audit of the entire OMO agent system pipeline: registration → injection → resolution → model routing
• The bug is a silent failure with no error logs or warnings, making it very difficult to notice
• All 72+ registered agents work correctly when called by exact name; only the discovery/awareness mechanism is broken
• Tested with 7 different plugin agents (code-simplifier, mermaid-expert, error-detective, c4-context, haskell-pro, typescript-pro, legacy-modernizer) — all executed successfully when called by name

Operating System

Linux (WSL2)

OpenCode Version

1.2.21

oh-my-opencode Version

3.11.0

[cuipengfei]

Related Issues

During investigation, I found several existing issues that are related to this bug:

Directly Related

• [Bug]: Custom agents from .opencode/agents/ invisible to orchestrator agents (Sisyphus/Atlas/Hephaestus) #1623 (closed) — Custom agents from .opencode/agents/ invisible to orchestrator agents
  This is an earlier report of the same root cause: plugin/user agents not visible to Sisyphus. It was closed, but the underlying problem persists in v3.11.0 with a different mechanism — the original issue was hardcoded agentSources, now it's the customAgentSummaries type mismatch (OpenCodeClient object passed where string[] is expected).

Related (Model Routing)

• Runtime fallback fails for delegated (task()) child sessions — 3 root causes in v3.10.0 #2357 (open) — Runtime fallback fails for delegated (task()) child sessions
  Our secondary finding (plugin/user agents inherit the MRU model from model.json instead of having explicit model routing) is directly related. When the MRU model is stale or unexpected, delegated agents use the wrong model silently.

Tangentially Related

• Feature Request: Allow plugin agents to override mode from frontmatter #1032 (open) — Allow plugin agents to override mode from frontmatter
  The agent-loader's AgentFrontmatter type lacks a model property, so even if an agent's YAML frontmatter specifies model:, it gets silently dropped during parsing. This is another facet of the incomplete agent metadata pipeline.

---

Filed by Sisyphus agent during a full-chain investigation of the OMO agent system.

[davincilll]

@cuipengfei
Please take a look at this PR. I also discovered this bug yesterday, and I spent quite a long time locating it before finally finding the solution.😂
#2392

[code-yeongyu]

[sisyphus-bot] Confirmed Bug — P2

Root Cause

In src/plugin-handlers/agent-config-handler.ts, createBuiltinAgents() is called with params.ctx.client (the OpenCode SDK client object) as the customAgentSummaries parameter (8th argument) instead of an actual array of agent summaries.

In src/agents/custom-agent-summaries.ts, parseRegisteredAgentSummaries() checks Array.isArray(input) — since the client object is not an array, it returns [] immediately. Result: zero plugin/user agent summaries are injected into the Sisyphus system prompt.

Affected Files

• src/plugin-handlers/agent-config-handler.ts — passes wrong value to createBuiltinAgents()
• src/agents/builtin-agents.ts — createBuiltinAgents function signature
• src/agents/custom-agent-summaries.ts — parseRegisteredAgentSummaries silently returns []

Fix Approach

1. At the call site in agent-config-handler.ts, pass the actual merged agent summaries array instead of ctx.client:

// Current (broken):
createBuiltinAgents(..., allDiscoveredSkills, params.ctx.client, ...)

// Fix: collect and pass actual agent summaries
const agentSummaries = collectRegisteredAgentSummaries(mergedAgents)
createBuiltinAgents(..., allDiscoveredSkills, agentSummaries, ...)

2. Add a type guard or warning log in parseRegisteredAgentSummaries to surface the type mismatch instead of silently returning empty.