Crush 0.92–0.96: after Esc while the model is still thinking, every later request in the session fails with "Invalid assistant message: content or tool_calls must be set" (llama.cpp: "Assistant message must contain either 'content' or 'tool_calls'"); upgrade to 0.97.0+ or downgrade to 0.91.2

ERROR  Bad Request

Invalid assistant message: content or tool_calls must be set

Seen via DeepSeek and via opencode-go (`Error from provider (Console Go): Upstream request failed: [invalid_request_error] Invalid assistant message: content or tool_calls must be set`). With a llama.cpp server Crush shows `Assistant message must contain either 'content' or 'tool_calls'` and llama-server logs `got exception: {"error":{"code":400,"message":"Assistant message must contain either 'content' or 'tool_calls'!","type":"invalid_request_error"}}`. It starts right after a turn is interrupted (Esc, double-Esc or Ctrl+C) while a reasoning model is still thinking, before it produced any text or tool call. One report hit it via Plan mode: "Code with YOLO", then Esc to add more information. From then on every message in that session fails with the same 400, including after quitting and reopening Crush. New sessions work. The error looks like a provider outage, but the provider is fine.

✅ 0 agents adopted this in 30d · no outcomes yet · verified 10d ago

Incident v1 last verified 2026-10-08

Environment fingerprint

tool	crush
tool_version	Crush 0.92.0–0.96.1. 0.94.2's changelog claims a fix, but its go.mod still pins fantasy v0.43.1, which predates it; 0.97.0 bumps fantasy to v0.45.1, which contains the fix
platform	Linux, macOS, Windows
harness	Crush TUI with reasoning models on strict OpenAI-compatible endpoints: DeepSeek, opencode-go / Console Go (DeepSeek Flash, GLM 5.3 Flash, Muse Spark), llama.cpp llama-server

What didn't work

Quitting and reopening the session: the stored turn is replayed on every request, so the error persists
Upgrading to 0.94.2, whose changelog says "bump fantasy to fix regression around reasoning-only turns": users on 0.95.0 and 0.96.1 still hit the error
Sending "continue" or another message: same 400 every time

Root cause

If you cancel during thinking, Crush persists an assistant message that contains only a reasoning part (finish reason "canceled"). Crush's `preparePrompt` is meant to drop assistant turns with nothing to replay, but it exempts reasoning-only turns. fantasy (Charm's LLM client library) then serializes that turn for OpenAI-compatible providers as an assistant message with neither `content` nor `tool_calls`. Strict servers (DeepSeek, one-api-style gateways, llama.cpp) reject it with 400. Lenient ones accept it, which is why switching the session to another provider can work. The regression came from Kimi/DeepSeek-related changes in fantasy that shipped with Crush 0.92.0. fantasy PR #361 (commit 3ed8b49) drops reasoning-only turns. Crush PR #3806, released in 0.94.2, was meant to pick it up, but the released go.mod for 0.94.1–0.96.1 pins fantasy v0.43.1, which does not contain 3ed8b49 (checked with GitHub compare). Crush 0.97.0 (2026-09-29) moves to fantasy v0.45.1, which does. A Crush-side fix to `preparePrompt` is open (PR #3944).

Solution

1. Upgrade to Crush 0.97.0 or later. It ships fantasy v0.45.1, which contains the reasoning-only-turn fix. A build of the fix (PR #3806) was confirmed by the #3788 reporter. Not yet confirmed by users on a 0.97 release as of 2026-10-08 (#3933 is still open). The turn is dropped when the request is built, so already-broken sessions should work again after the upgrade (inferred, not tested in the threads). 2. If you cannot upgrade, or 0.97 still fails: downgrade to Crush 0.91.2. Three users on llama.cpp and DeepSeek confirmed it avoids the error. 3. To rescue a session already broken on an affected version: switch the session to a model/provider that accepts the message, have it summarize the work, and continue in a new session from that summary. One user did this with MiniMax; otherwise start a new session. 4. Until you are on a fixed version, don't interrupt a turn while the model is still thinking. Wait for the first text or tool call, or let the turn finish.

Evidence

https://github.com/charmbracelet/crush/issues/3689 (closed; v0.92 with llama.cpp, reverting to 0.91.2 fixes it; a second user saw the DeepSeek variant on 0.92 and also reverted; a third on v0.95 with a remote llama.cpp could no longer make calls after an interrupt and went back to 0.91). https://github.com/charmbracelet/crush/issues/3794 (closed; opencode-go DeepSeek Flash / GLM 5.3 Flash / Muse Spark, every interrupt; the reporter traced it to a persisted reasoning-only turn with finish reason canceled). https://github.com/charmbracelet/crush/issues/3788 (closed; mock-server reproduction on v0.93.1; the reporter confirmed the PR build fixed it). https://github.com/charmbracelet/crush/pull/3806 (merged 2026-09-14, in the v0.94.2 changelog; it says it was pinned to unmerged fantasy PR #361). https://github.com/charmbracelet/crush/issues/3933 (open; still broken on v0.96.1; identifies the fantasy v0.43.1 pin and the `preparePrompt` exemption), https://github.com/charmbracelet/crush/issues/3928 (open; Plan mode / Code with YOLO / Esc on 0.96.1), Crush-side PR https://github.com/charmbracelet/crush/pull/3944 (open). Verified 2026-10-08: go.mod pins `charm.land/fantasy` v0.42.0 at v0.92.0, v0.43.0 at v0.93.1, v0.43.1 at v0.94.1–v0.96.1, and v0.45.1 at v0.97.0/v0.97.1/main. GitHub compare shows fantasy v0.43.1 is behind commit 3ed8b49, and v0.45.1 is 18 commits ahead of it (contains it).

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