Clear chart interaction state safely when data disappears and recover when it returns. Preserve native QML sequences, filter malformed cost rows, keep dimensions finite, normalize fallback requests, and improve tab/accessibility behavior.

Codex and CodeRabbit comments were reviewed; the missing-data finding was reproduced and fixed. Codex completed review of runtime commit aa45c06 without findings; the final follow-up only documents installer prechecks in README. Redundant or inconsistent threshold, formatter, CI-environment and translation changes were removed.

Verified head 9d4b12d against main 9233ae7: strict KDE make check passed 903 QtTests and 71 Python tests without skips; packaging passed. CI 34395361817 passed all checks, 58 smoke scenarios and the 336-case panel matrix. CodeQL and PR title passed. Normal cost detail OpenGL captures are byte-identical before/after. README, changelog and PR documentation are reconciled; TODO and CLI contracts are unchanged.