Collapse the four definitions of "one log line" into LogLine (timestamp,
level, source, text) with a single renderer and parser. agent.log lines
now carry the uniform prefix, absorbing the ssxng: event marker into the
source column; legacy lines degrade to raw display without rewriting.
Level detection moves into the row model with a classic three-level
taxonomy whose unified-log projection stays unchanged.
The diagnostics log view merges GUI events and the agent.log tail through
DiagnosticLogIntake into one time-ordered list with level and source
filters; the tail window logic moves into the intake and blank lines are
kept for raw fidelity. The report whitelist projection and unified-log
routing are unchanged.