Issue 1524 — usersAssignProject: setting a role to "-- no role --" never un-assigns (map drops 0 rows)

Issue: #1524 Branch: fix/issue-1524 Status: VERIFIED-FIXED (2026-09-17)

Symptom

On the modern Assign Test Project Roles screen, clearing a user's role to -- no role -- and clicking Save Changes is silently ignored: the request succeeds ({"status":"ok"}) but the user keeps their previous role, and the table reloads showing the old role. Same flow on Assign Test Plan Roles was verified working (the plan screen keeps 0 entries, so it was never affected).

Measured after the failing save:

SELECT * FROM user_testproject_roles;
-- +---------+----------------+---------+
-- | user_id | testproject_id | role_id |
-- +---------+----------------+---------+
-- |       1 |              1 |       9 |   <-- still assigned, should be gone
-- +---------+----------------+---------+

Repro steps

1. Fresh-import DB. Recreate fixture: nodes FixtureProject (id 1, node_type 1), FixturePlan (id 2, node_type 5), rows in testprojects/testplans; the single active user is admin (id 1). (Fresh DB has no projects at all.)
2. Log in as admin/admin at http://localhost:8082, open gui/templates/usermanagement/usersAssignProject.html?tproject_id=1.
3. Set the only user's Assigned Role to leader (9) and save. → user_testproject_roles = (1,1,9).
4. Set the same select back to -- no role -- (0) and save.
5. Before fix: no error, role NOT removed, (1,1,9) still present. After fix: row deleted, SELECT returns 0 rows.

Root cause

gui/templates/usermanagement/usersAssignProject.html:198:

if (uid && roleVal > 0) assignments[uid] = roleVal;

Chain:

1. The map builder filters out every user whose role select value is 0, so a "clear role" action yields assignments == {} for a single user (measured live: builtAssignments = "{}" with selectValue = "0").
2. api/roles/index.php:511-513: PUT /tproject-roles short-circuits an empty map as a no-op (legacy parity guard, added with #1523) → no manager call.
3. Even without that guard, api/roles/index.php:516-517 deletes only array_keys($assignments); the cleared user id is absent from the map, so deleteUserRoles(tproject_id, [...]) never targets their row — testproject.class.php:1831-1839 also treats [] as a no-op.

Why it broke: the modern screen dropped the legacy semantic. Legacy lib/usermanagement/usersAssign.php:557-573 (doUpdate) deletes for array_keys($map) even when entries are 0 and re-adds only if ($role_id). The plan twin usersAssignPlan.html:182 kept this with if (uid) and was verified working end-to-end.

Fix

gui/templates/usermanagement/usersAssignProject.html:198:

if (uid) assignments[uid] = roleVal;

The map now always contains every visible user; users with role 0 are deleted (correct) and roles > 0 re-added. Empty map can only occur with zero user rows (nothing to delete), so the #1523 empty-map no-op guard stays valid. BFF and manager layer required no change (the {uid:0} contract already deletes).

Screenshots

Assign Test Project Roles screen (normal state, admin assigned leader):

Clearing the role to -- no role -- before saving (changed-badge visible):

Verification (regression matrix, all PASS)

Case	Result
Assign leader → save → row exists (1,1,9)	PASS
Clear to -- no role -- → save → row DELETED	PASS (bug fixed)
Re-assign after a clear → row re-appears	PASS
Multi-user: admin keeps leader, bob cleared → only bob's row deleted	PASS
Plan screen (project 1 / plan 2): assign leader, clear → row deleted (control)	PASS
Console + events table after full walk	no new Error/Warning; only AUDIT/16 INFO rows

Regression suite: tmp/TLU_Test_Cases.md → Suite 1525 (8/8 PASS).