Silent failure: large input received, zero output produced, no error surfaced

What Happened

During an active development session (ZeroCopy Möbius V6 DEX, 2026-05-09), a large user message was sent containing:

• ~230 lines of Solidity contract code (v6_tmi_ring.sol)
• ~60 lines of architecture explanation (WASM / JS / Ethereum finality separation)
• A direct question asking for feedback on the architecture

Claude received the input — the message appeared in the conversation — but produced zero output. No response text, no tool calls, nothing. Complete silence.

The user had to re-prompt to get any response. Even then, the first response misread the failure and began documenting architecture content instead of acknowledging the failure itself. A second re-prompt was required to clarify what had actually gone wrong.

Failure Classification

Type: Response generation failure — input processed, output not produced

Probable cause (one or more of):

• Tool chain call error that failed silently before response was generated
• Response stream interrupted or dropped before delivery to user
• Context window pressure from large input causing generation to abort silently
• API timeout on large input with no error surfaced to user

Not: A content refusal, permission issue, or misunderstanding. The input was entirely legitimate technical content.

Impact

• User lost time waiting for output that never came
• Required two re-prompts just to establish what had failed
• Workflow interrupted mid-session during active development work

Input Size

• ~230 lines Solidity
• ~60 lines architecture text
• One question

Large but not unprecedented. No unusual characters, no ambiguous instructions.

Pattern

This is not an isolated incident. Multiple prior sessions have shown silent failures when input is large (contracts, architecture dumps, multi-part technical context). The failure is always silent — no error message, no partial response, no spinner timeout, no indication anything went wrong.

Expected Behavior / Recommendation

Surface a visible error or partial acknowledgement when response generation fails after input is received.

Silent failure with zero output is worse than an error message — the user cannot distinguish between "Claude is thinking" and "Claude has failed." A simple "I received your message but encountered an error generating a response — please re-send or try a shorter message" would resolve this entirely.

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Reported via Claude Code session. Local report: CLAUDE_INPUT_RECEIVED_NO_OUTPUT_FAILURE_20260509.md