{"version":"2.1.265","anchor":"tool-use-ids-with-a-reserved-prefix-are-now-classified-as-un","canonical_anchor":"tool-use-ids-with-a-reserved-prefix-are-now-classified-as-un","heading":"Tool-use IDs with a reserved prefix are now classified as underivable_excluded","tier":"internal","area":"Sessions","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.265\/e\/tool-use-ids-with-a-reserved-prefix-are-now-classified-as-un","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.265","markdown":"### Tool-use IDs with a reserved prefix are now classified as underivable_excluded\n\nTool calls with a special reserved ID prefix are now excluded from resume history reconstruction\n\n**Unclear.** What the reserved ID prefix specifically identifies is not shown by the evidence.\n\n**What**\n\nWhen Claude Code resumes a session and figures out which prior tool calls can be reconstructed, a tool call whose ID starts with a specific reserved prefix is now immediately classified as `\"underivable_excluded\"`, before the normal checks for whether it was superseded or mismatched even run.\n\n**Why**\n\nThis ensures tool calls carrying that reserved ID prefix are never mistakenly reconstructed during resume, treating them as excluded from the start rather than relying on the standard classification logic to catch them.\n\n- Area: Sessions\n- Names: `underivable_excluded`\n- Tier: Under the hood\n- Useful: 1\/5\n- Signal: 1\/5"}