Checkpoint: Drop-Folder Converter

Combining what the last three lessons built

This checkpoint doesn't introduce new MarkItDown API. It combines:

• Lesson 5's loop: convert every file in a folder, write .md output, track a summary.
• Lesson 7's custom converter: register_converter(), so the synthetic .ticket format is understood before the loop even runs.
• Lesson 8's lesson about failure modes: format detection isn't infallible, and this time the failure is a real one worth handling, not a silently-wrong hint but a file nothing can convert at all.

The result is close to a real "drop folder" ingestion job: a service that watches a directory, converts whatever lands in it, and has to keep running even when something in that directory isn't a format it understands.

The one new thing: handling UnsupportedFormatException

Lesson 5's fixtures/ folder never triggered a real failure, every file in it was something MarkItDown could convert. This lesson's data/ folder has three files: two .ticket files (handled by TicketConverter, registered up front) and one firmware_blob.bin, a stand-in for "someone dropped a file into this folder that doesn't correspond to any known format", raw binary bytes with no structure a text-oriented converter could make sense of.

try:
    result = md.convert(source_path)
except UnsupportedFormatException:
    results.append((source_path.name, "SKIPPED (unsupported format)", 0))
    continue

UnsupportedFormatException (from markitdown._exceptions) is what .convert() raises when no registered converter, built-in or custom, claims a file. Catching it and moving on is what turns this from a script that dies on the first weird file into one that processes an entire real-world folder, warts and all.

The code, piece by piece

md.register_converter(TicketConverter())

Same registration from Lesson 7, done once before the loop starts, so every .ticket file the loop encounters is already handled by the time .convert() is called on it.

for source_path in source_files:
    try:
        result = md.convert(source_path)
    except UnsupportedFormatException:
        results.append((source_path.name, "SKIPPED (unsupported format)", 0))
        continue
    ...

The loop body is Lesson 5's, with one branch added: a file that fails conversion gets logged as skipped instead of crashing the run.