Live re-run after the c995bc2 Device-DN fix returned "A syntax error
has occurred" from Informix. Cause: the explanatory comment block
documenting why tkpatternusage=2 was added landed *inside* the
translation_chain f-string instead of above it. Python's `#` line
comments only work outside string literals — inside an f-string,
each `#` is literal text. Informix received SQL with `#` lines after
the JOIN clauses, parsed them as illegal tokens, and rejected.
Offline tests didn't catch this because the FakeAxlClient dispatches
on substring matches without actually parsing the SQL. The bug only
manifested when the SQL hit a real Informix engine.
Fix: move the comment block ABOVE the `sql = f"""` assignment so it
becomes a real Python comment instead of literal SQL text.
Sentinel test added (test_no_python_comment_chars_leak_into_sql):
captures all SQL emitted by a cti_failsafe_reachability call and
asserts no `#` character appears anywhere. CUCM's data dictionary
doesn't use `#` in any table or column name, and Informix uses
`--` / `/* */` for comments — so a `#` in any captured query is
almost certainly an escaped Python comment. Catches this exact
class of regression for any future contributor.
Tests: cti suite 33 → 34; full mcaxl suite 271 → 272 passing.
Operational impact: this regression made cti_failsafe_reachability
unrunnable against any live cluster between c995bc2 and this fix.
The Bingham 6→4 finding-reduction verification queued in 008 is
unblocked once the MCP server reloads with this commit.
Ryan Malloy
1b92f83dc4