fix: /PUT state not following spec with 409 - Conflict

[chomatdam]

Problem

State resources (/xapi/activities/state) were incorrectly subject to concurrency header requirements (If-Match / If-None-Match) when a document already existed. Per the xAPI 1.0.3 spec §3.1 and xAPI 2.0.0, state resources are explicitly exempt from concurrency header requirements:

"The State Resource will permit PUT, POST and DELETE requests without concurrency headers, since state conflicts are unlikely."

This meant that a second PUT to a state resource (overwriting an existing document) without concurrency headers would incorrectly return a 409 Conflict instead of succeeding.

Impact

(since last LRSQL release)

Articulate Storyline/Rise courses using scormdriver.js for xAPI communication do not send If-Match or If-None-Match headers when updating state documents. This caused state PUT requests to fail with 409 Conflict when a state document already existed, breaking Articulate content playback and progress tracking.

Changes

src/main/com/yetanalytics/lrs/pedestal/routes/documents.cljc

• Added state resource exemption: when params-type is :xapi.activities.state.PUT.request/params, PUTs without concurrency headers are allowed regardless of whether a document already exists

src/test/com/yetanalytics/lrs_test.clj

Added document-concurrency-test that validates version-aware concurrency behavior:

Resource	Version	No existing doc	Existing doc (no headers)
State	1.0.3	204 ✅	204 ✅
State	2.0.0	204 ✅	204 ✅

[chomatdam]

I opened an issue regarding 2.0.0 conformance tests not matching the spec:
adlnet/lrs-conformance-test-suite#282