pi-agent-core: crash when calling .filter() on message.content / assistantMessage.content when content is not an array

[jepson-liu]

What happened?

In @mariozechner/pi-agent-core’s agent-loop, two call sites invoke .filter() directly on message.content and assistantMessage.content without checking that the value is an array. When a sub-agent (or another code path) yields a message whose content is a string or other non-array value, Node throws:

TypeError: xxx.content.filter is not a function

The assistant message ends up with stopReason: "error" and the agent loop stops. This was reproduced upstream in OpenClaw when using sessions_spawn with runtime: "subagent"; see openclaw/openclaw#51390.

Corresponding source in this repo:

• Main loop: message.content.filter(...) in packages/agent/src/agent-loop.ts (around line 201)
• executeToolCalls: assistantMessage.content.filter(...) (around line 343)

Other parts of the same file already iterate content defensively; these sites should follow the same pattern (e.g. (Array.isArray(content) ? content : []).filter(...)).

Steps to reproduce

1. Run an agent through a path that can produce a message with non-array content (as in upstream: parent uses sessions_spawn, child runtime: "subagent").
2. Ensure the child returns a message where content is a string (or otherwise not an array).
3. When the parent agent-loop processes that message, execution hits one of the .filter() sites and throws.

Expected behavior

The agent loop must not crash with .filter is not a function when content is not an array. Non-array content should be treated as “no structured content blocks” or normalized according to the type contract before resolving tool calls.

Version

0.60.0

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[badlogic]

here are the involved types. content is an array. if your software ignores all types and sends a string there, then that's on you, not on pi. fix your shit.