pi-coding-agent's _getUserMessageText calls content.filter(...) on user
messages; if a message lands in state.messages with content === undefined
(string or array expected), the library throws
"Cannot read properties of undefined (reading 'filter')", which gets
caught and stored on session.state.errorMessage and rethrown without a
stack. Fusion's existing message-content guard already normalized
assistant/toolResult messages — extend it to user messages as well, and
sweep state.messages once when the guard is installed so content loaded
from a session file is repaired before the first event fires.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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