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llama-server bug fails to enforce JSON schema constraints

The llama-server tool, specifically version b10868, exhibits a bug where it fails to enforce schema constraints when the `response_format` is set to `json_schema` with a schema directly nested under `response_format`. Instead of applying the provided schema, the server returns unconstrained text, similar to when no `response_format` is specified. This issue is particularly insidious because the server still returns an HTTP 200 status code and logs no errors, making it difficult to detect. A previous fix in March 2025 addressed a similar issue but only for a nested `json_schema` structure, leaving the direct `response_format.schema` case unaddressed. AI

IMPACT This bug could lead to unexpected data formatting issues in applications relying on llama-server for structured output.

RANK_REASON Bug report on a specific tool's functionality.

Read on dev.to — LLM tag →

AI-generated summary · Google Gemini · from 1 sources. How we write summaries →

llama-server bug fails to enforce JSON schema constraints

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33 / 100
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COVERAGE [1]

  1. dev.to — LLM tag TIER_1 English(EN) · The Homelab Postmortem ·

    llama-server ignores the response_format its own README shows, and returns 200

    <p><strong>TL;DR</strong>: <code>tools/server/README.md</code> gives <code>{"type": "json_schema", "schema": {...}}</code> as an example of schema-constrained output. On a build from this week the reply to that form is <strong>byte-identical</strong> to the reply when you send no…