Web UI infinite response loop with custom openai-compatible provider (NVIDIA NIM) #37855

Description

Bug Description

Web UI (opencode web) enters an infinite response loop for a simple, non-tool-call chat message. The same short reply gets regenerated repeatedly (5+ times) instead of stopping after the first finish_reason: "stop". This does not happen in the CLI/TUI (opencode command) — only in opencode web.

Environment

• OpenCode version: 1.18.3
• Platform: GitHub Codespaces (Ubuntu, devcontainer)
• Provider: Custom @ai-sdk/openai-compatible provider pointing to NVIDIA NIM (https://integrate.api.nvidia.com/v1)
• Models tested: z-ai/glm-5.2, deepseek-ai/deepseek-v4-pro, minimaxai/minimax-m3, nvidia/nemotron-3-ultra-550b-a55b — all affected
• Started with: opencode web --port 4096 --hostname 0.0.0.0

Steps to Reproduce

1. Configure a custom openai-compatible provider in opencode.json pointing to NVIDIA NIM
2. Run opencode web --port 4096 --hostname 0.0.0.0
3. Open the web UI via forwarded port in browser
4. Send a simple message (e.g. "chào" / "hi")
5. Observe: the same short reply is generated repeatedly, without stopping

Expected Behavior

Model should respond once and stop, respecting finish_reason: "stop" — exactly as it does in CLI/TUI mode with the same provider/model/config.

Actual Behavior

Same or near-identical short reply keeps regenerating in a loop until manually interrupted.

Verification / Isolation Steps Taken

• Called the NVIDIA API directly via curl with the same model/payload — got a single clean response with "finish_reason":"stop", HTTP 200. Confirms the issue is not on the provider/API side.
• Ran the identical prompt/model through CLI (opencode in terminal, not opencode web) — worked correctly, single response, no loop.
• Reproducible across multiple different models on the same custom provider, suggesting the bug is in opencode web's session/stream handling, not model-specific.

Possibly Related

• Session Loop Termination Condition Fails Causing Infinite Loop #13577 (Session Loop Termination Condition Fails Causing Infinite Loop — string comparison bug on message IDs)
• [Web UI] Task never stops — agent runs indefinitely when using opencode serve #26365 ([Web UI] Task never stops — agent runs indefinitely when using opencode serve)
• Bug: OpenCode enters infinite loop after tool calls complete (Zen/big-pickle) #26220 (OpenCode enters infinite loop after tool calls complete)

Plugins

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OpenCode version

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Steps to reproduce

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Screenshot and/or share link

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Operating System

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Terminal

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