Stop the SQLite timeline table dropping rows with nothing said

[dchaudhari7177]

Towards #343.

Scope — most of that issue is already fixed

Reading the code against the issue, three of its four parts have landed since it was written:

Issue item	State on main
HindsightEncoder.default() dispatches on Chrome.X, so Firefox siblings fall through	Fixed — the chain tests WebBrowser.X
Service Worker classes have no encoder branch	Fixed — all five ServiceWorker*Item branches exist
JSONL drop is invisible	Fixed — warn_unhandled() reports class and derived data_type
generate_sqlite() storage loop has no else	Fixed — unhandled_storage counter, and a service worker INSERT branch

What is left is the one the issue names but that did not get the fix: "both dispatchers need a final else that logs". The storage loop got its else. The timeline loop did not.

The live drop it is hiding

This is not only a defensive change. get_extension_settings appends extension (installed) and extension (updated) items to parsed_artifacts (chrome.py:2414), and the XLSX writer has a branch for them (analysis.py:1952). The SQLite timeline dispatch has neither a branch nor an else, so those events are dropped.

Measured on main, feeding two such items through generate_sqlite:

parsed_artifacts: ['extension (installed)', 'extension (updated)']
SELECT type FROM timeline  ->  []

Same shape as the Service Worker case the issue measured: parsed correctly, counted correctly, reported by the run, and then never written — so anyone working from SQLite has no indication the artifact exists.

The change

• extension joins the preference / site setting / notification / … branch, whose column set it already fits (PreferenceItem, and the XLSX branch writes exactly these fields).
• A final else counting into unhandled_timeline, reported one line per row_type with a count, mirroring unhandled_storage exactly.

The else is the more important half. The branch fixes the one artifact missing today; the else is what makes the next one a reported number rather than a silent absence.

Verification

Four tests driving generate_sqlite against a real on-disk SQLite file and reading the rows back. Three fail on main:

FAILED test_extension_install_events_reach_the_timeline_table
FAILED test_an_unhandled_row_type_is_reported_rather_than_dropped_silently
FAILED test_unhandled_rows_are_counted_not_reported_once_each

The fourth pins that a handled row_type is not reported as missing, so the else cannot start crying wolf.

Full suite on this branch: 243 passed, 2 skipped, 80 subtests passed. Python 3.12.4.

Not done here

I have deliberately left #343 open rather than closing it, because two of its questions are yours to settle and are not answered by this:

• whether the SQLite storage table should hold Service Worker rows or get its own table (they are in storage today);
• whether Service Worker JSONL rows should keep borrowing chrome:local_storage:entry-style data_type names — they currently use chrome:service_worker:*, which reads correct to me, but you flagged the collection they live in rather than the names.

Happy to take either on separately.