Independent synthetic demonstration

Find what changed
in the third request.

Create, confirm, assessment. Compare the prepared requests without contacting a service or exposing credential values.

Actual Requests preparation. Seven passing checks. No network sends.

One request breaks the fixture.

Differences in the intentionally broken third step
Field	Expected preparation	Broken preparation
content_type	`application/json`	`application/x-www-form-urlencoded`
header_names	`["accept","accept-encoding","connection","content-length","content-type","cookie","origin","referer","user-agent"]`	`["content-length","content-type"]`
cookie_names	`["demo_session"]`	`[]`
payload_shape	`{"$":"dict","$.application_id":"str","$.confirmed":"bool"}`	`{"$":"dict","$.application_id":"str","$.confirmed":"str"}`

The corrected fixture retains the same session and JSON encoding. Its metadata comparison has zero differences.

with requests.Session() as session:
    prepared = session.prepare_request(
        requests.Request("POST", url, json=payload))

Run python -m unittest -v and python flow_review.py. Python 3.11+ and Requests are required.