fix(provider): Z.AI GLM overflow error not classified as context overflow, causing chain compaction #27629

Description

When Z.AI GLM models (glm-5-turbo, glm-5, glm-5.1) exceed their 200K context window, they return an error that is not recognized by opencode's OVERFLOW_PATTERNS in packages/opencode/src/provider/error.ts. This causes the error to be classified as a generic APICallError instead of ContextOverflowError, preventing auto-compaction and resulting in an unrecoverable chain compaction loop.

Observed Behavior

1. Session context fills past 200K threshold (common with many MCP tools)
2. opencode attempts compaction
3. Z.AI returns: "tokens in request more than max tokens allowed"
4. opencode classifies this as generic error (not overflow)
5. No compaction occurs → session retries → same error → infinite loop
6. Session becomes permanently unusable without DB intervention

Expected Behavior

The error message "tokens in request more than max tokens allowed" should be classified as context overflow, triggering auto-compaction.

Error Text

tokens in request more than max tokens allowed

Root Cause

OVERFLOW_PATTERNS in packages/opencode/src/provider/error.ts does not include a pattern matching Z.AI GLM's overflow error message.

Proposed Fix

Add the following pattern to OVERFLOW_PATTERNS:

/tokens in request more than max tokens allowed/i,

Related Issues

• fix(provider): classify "tokens in request more than max tokens allowed" as context overflow #27519 — same class of bug (OpenAI-compatible providers using this error phrasing)
• Session permanently stuck after auto-compaction: post-compaction auto-trigger fires tool_use without tool_result error and is non-recoverable #27594 — sessions permanently stuck after compaction (same downstream consequence)
• Auto-compaction triggers at ~200k tokens instead of model's actual context window (1M) #15871 — hardcoded context window ignoring actual model limits
• OAuth/Codex GPT-5.5 behaves like ~400k context while GPT-5.4 shows 1M #24561 — context limit mismatch between metadata and actual provider limits

Environment

• OpenCode version: 1.14.48
• Provider: zai-coding-plan (GLM-5-Turbo)
• The GLM-5 family (glm-5, glm-5-turbo, glm-5.1) all share 200K context documentation