write the logging guide page

[carlos-granados]

Replaces the logging placeholder. Split into the two distinct things the word covers: your script's own output reaching the editor console, and the debugger's own log.

Verified against handler_dbgp.c and lib/log.c:

• the stderr DBGp command is unimplemented and always answers success="0", so standard error is never captured — error_log(), fwrite(STDERR, ...) and startup errors do not reach the console. Called out in a note, since it is the likely cause of "I printed it and it is not there".
• stdout modes are copy (editor and response) and redirect (editor only, stripped from the response)
• the log file is opened "a" and flushed per line, and is shared by every process, hence the leading PID
• php_debugger.log_level is a threshold — higher is more verbose. Level 5 is the raw protocol XML in both directions; level 10 adds trigger checks and path-mapping decisions.
• with no log file set, the logger falls through to the PHP error log path, which writes Critical and Error only. So hard failures leave a trace with no configuration, and anything gentler is dropped.

[github-actions]

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2026-09-06 07:20 UTC