Fixed
Cross-session x send-output transferred unpredictable content (issue #598)
Pressing x to transfer output from session A → session B sometimes delivered content from a prior conversation rather than the most-recent assistant response. The reporter described it as 'unpredictable — never the last output'.
Root cause: getSessionContent read the last assistant message via Instance.ClaudeSessionID, which goes stale every time Claude is resumed. The live CLAUDE_SESSION_ID sits in the tmux env, but the stored ID keeps pointing at the prior JSONL.
Fix: adds Instance.RefreshLiveSessionIDs() and routes getSessionContent through a testable getSessionContentWithLive(inst, liveID) helper that prefers the live tmux env ID over any stored value before the JSONL lookup. Tmux scrollback fallback unchanged.
Tests: TestGetSessionContentWithLive_PrefersFreshIDOverStoredStaleID + two back-compat tests in internal/ui/send_output_content_test.go; TestInstance_RefreshLiveSessionIDs_* safety contract tests in internal/session/instance_test.go. PR #638.
Release notes
Assets uploaded manually via goreleaser --skip=publish + gh release upload because the Release workflow's go test -race ./... step is blocked by pre-existing red tests for issue #601 (PR #640 is the fix, queued). Once #640 merges, subsequent releases will revert to fully automated.