[harness] worktree-agent-resume: A completed worktree-isolated agent cannot be resumed by message (No transcript found) although names are said

Context. Solo-operator project using Claude Code (desktop app, Windows 11) with a lead session on Claude Fable 5.1 orchestrating Opus 5.5 / Sonnet subagents (worktree-isolated), a JSON task store, PreToolUse/SubagentStop hooks and a harvest-train commit flow. This finding was measured on or before 2026-09-22 and filed on 2026-09-28 at the operator's request; numbers are from tool output. No secrets, identities or private paths.

Class / model / severity. worktree-agent-resume / harness / LOW

Finding. A completed worktree-isolated agent cannot be resumed by message (No transcript found) although names are said to keep working; every checkpoint continuation became a fresh dispatch.

Evidence (measured). Board #1225 cases 2-3; this session api-lane-2 -> api-lane-3.

Minimal reproduction. Complete an isolation=worktree agent and SendMessage it.

Ask. Document, or keep the transcript for resumption.