{"version":"2.1.138","anchor":"advanced-mid-conversation-system-beta-override","canonical_anchor":"advanced-mid-conversation-system-beta-override","heading":"Advanced Mid-Conversation System Beta Override","tier":null,"area":null,"scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.138\/e\/advanced-mid-conversation-system-beta-override","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.138","markdown":"### Advanced Mid-Conversation System Beta Override\n\n**What**\n\nClaude Code now allows the `CLAUDE_CODE_MID_CONVERSATION_SYSTEM` environment override to enable the `mid-conversation-system-2026-04-07` beta even when `ANTHROPIC_BASE_URL` is set to a non-default host.\n\n**Usage**\n\n`ANTHROPIC_BASE_URL=https:\/\/your-compatible-endpoint.example \\ CLAUDE_CODE_MID_CONVERSATION_SYSTEM=claude-sonnet-4-5 \\ claude` **Details** - This is not a new public command or setting; the environment variable already existed in 2.1.137. - In 2.1.137, the mid-conversation beta check returned false whenever the base URL was not `api.anthropic.com`. - In 2.1.138, that base URL check is bypassed when `CLAUDE_CODE_MID_CONVERSATION_SYSTEM` is present. - The beta is still constrained by the surrounding provider and model checks, and `CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS` can still disable experimental betas. **Evidence** Mid-conversation beta gate now checks `(!If() && !process.env.CLAUDE_CODE_MID_CONVERSATION_SYSTEM)` before adding `mid-conversation-system-2026-04-07` (search for `\"CLAUDE_CODE_MID_CONVERSATION_SYSTEM\"` and `\"mid-conversation-system-2026-04-07\"`)."}