AI Code Scan Bugfixes

Bugs found by an AI-assisted code scan of the fork on 2026-09-28, and the fix bundles raised for them. Unlike the other pages, nothing here is a new feature: these are correctness fixes, nearly all in code inherited from upstream.

How the scan was done

Scope: qmlui (the QLC+ 5 UI) and engine. The QtWidgets v4 UI (ui/), plugins and webaccess were not scanned.
Method: targeted, not exhaustive. Pattern searches (lookups used without a null check, unchecked casts, signed-byte sign extension, index bounds, divisions by values that can be zero, lock and lifetime issues), then close reading of the riskiest files: the Function Manager tree, undo/redo, VC Cue List and Frame, Simple Desk, ShowRunner, ChaserRunner, GenericFader/FadeChannel, Universe, Scene, Collection, EFX, RGB Matrix, Doc and MasterTimer.
Verification: every fixed bug was first reproduced on unmodified upstream/master, either in the running app (headless session driven by xdotool) or with a regression unit test that fails on upstream and passes with the fix. Where neither was practical, the finding is marked code review.
Tests: the full engine unit test suite passes with all bundles applied, on both upstream/master and the fork's master. The exceptions are qlcfile and rgbtext, which fail the same way on unmodified upstream (test resources and fonts in the test environment).

Column meanings:

Confidence: how sure the scan was that the defect is real before verifying it.
Patch risk: how likely the fix is to disturb something else.
Verified: how the bug was confirmed on upstream.
Origin: where the buggy code came from, per git blame.

Findings

qmlui (first pass)

#	Where	Bug	Origin	Confidence	Patch risk	Verified	Fork PR
1	`treemodel.cpp`	Deleting, moving or renaming a Function removed a folder with the same name (and every Function in it) from the tree; the deleted Function's row stayed behind with no icon	Upstream, 2018 `TreeModel`	High	Medium	App + model harness	#80
2	`functionmanager.cpp` `addFunctiontoDoc()`	A new Function was added to the existing selection, so Delete also removed the Functions selected before	Upstream, 2018. The fork's container-from-selection inherits it	High	Low	App	#80
3	`tardis.cpp`	After undoing everything, a new action didn't discard the undone ones, so further undos replayed them	Upstream, 2017 Tardis	High	Low	App (log)	#81
3b	`tardis.cpp` `redoAction()`	One redo also applied the first action of the next batch	Upstream, 2017 Tardis	High	Low	App (log)	#81
4	`tardis.cpp`	Undo history changed on two threads without a lock	Upstream, 2017 Tardis	High (race exists); low (how often)	Medium	Code review	#81
5	`vccuelist.cpp`	Previous while stopped (or Next on a backward Chaser) went to step -2: "Run next" started with no step shown, "Select" lost the selection	Upstream, 2018 (the v4 UI handles it)	High	Low	App	#82
6	`simpledesk.cpp`	Unpatched channel values above 127 shown as ~4 billion after a universe switch	Upstream, 2020	High	Very low	Code review	#83
7	`functionmanager.cpp` `createFolder()`	Duplicate check used the wrong path separator and a bare prefix match: nested duplicates allowed, "Foo" refused next to "Foobar"	Upstream, 2018	High	Low	App	#80
8	`functionmanager.cpp` `deleteSelectedFolders()`	Deleting an empty folder left its empty subfolders registered; recreating them was refused	Upstream: the 2026-07 fix for #2058 only covered folders with Functions	Medium-high	Low	App	#80
9	`contextmanager.cpp`	Fixture distribution sorted positions as unsigned integers (negative/fractional positions misordered)	Upstream, 2018	High	Very low	Code review	#83
10	`listmodel.cpp`	Role bound check let one role past the end through; negative rows not rejected	Upstream, 2016	High (defect); low (impact)	Very low	Code review	#83

Found while fixing the first pass

#	Where	Bug	Origin	Confidence	Patch risk	Verified	Fork PR
A	`treemodel.cpp` `addItem()`	Items added to a newly created empty folder didn't appear until the tree was rebuilt	Upstream	High	Low	App	#80
B	`contextmanager.cpp` `setFixturesDistribution()`	Vertical distribution in Front/Side views (and horizontal in Right side) wrote positions without undoing the 2D axis flip: fixtures landed mirrored or off the grid	Upstream, 2018	High	Low	App	#83

Engine and remaining qmlui (second pass)

#	Where	Bug	Origin	Confidence	Patch risk	Verified	Fork PR
E1	`showrunner.cpp`	Two Show items using the same Function (back-to-back, e.g. after Split, or overlapping on two tracks): the second item never played	Upstream, 2014–2016	High	Medium	Unit test + app	#84
E2	`rgbmatrix.cpp`	Deleting the fixture group of a running (or previewed) RGB Matrix left it using freed memory	Upstream	High	Low	Unit test	#85
E3	`doc.cpp` + qmlui `moveFixture()`	Moving a fixture left its HTP/LTP types and defaults at the old address (none at the new one); deleting one left them set up and its last LTP value on the output	Upstream, old	High	Medium	Unit test	#86
E4	`chaserrunner.cpp`	Random order could report a step that doesn't exist (single step, or going backward)	Upstream	High	Low	Unit test	#87
E5	`chaserrunner.cpp`	Random order not rebuilt when steps were added or removed while running	Upstream	Medium-high	Low	Unit test	#87
E6	`collection.cpp`	A Collection's duration was the sum of its members, though they run in parallel	Upstream, 2015	High	Low	Unit test	#87
E7	`collection.cpp` `adjustAttribute()`	Intensity overrides looked up by position in the current member list; out of range if members change while running	Upstream, 2015/2017	Medium	Low	Code review	Not yet fixed
E8	`efx.cpp`	Only the first head of a deleted multi-head fixture was removed; EFX fixture entries could be deleted while the MasterTimer thread used them	Upstream, 2012/2013	High (heads); medium (race)	Low (heads); medium (lock)	Unit test (heads), code review (race)	#85
E9	`showrunner.cpp`	Starting a Show mid-way compared beat-based items with a time in ms: below 60 BPM items still to come were skipped	Upstream, 2012 condition reused for beats	Medium-high	Low	Unit test	#84
E10	`efx.cpp` `loopDuration()`	A fade in not shorter than the duration wrapped the loop to ~49 days, freezing the EFX (reachable from the EFX editor)	Upstream	High	Low	Unit test	#87
E11	`rgbmatrix.cpp` `setTotalDuration()`	Integer division by zero (crash) with a 0-step algorithm. Only the v4 Show Manager calls it	Upstream	High	Very low	Unit test (SIGFPE on upstream)	#87
Q1	`chasereditor.cpp` `setTempoType()`	Switching a Chaser's tempo type overflowed the duration of infinite-hold steps, so cues no longer held	Upstream, 2016	High	Very low	Code review	#87
Q2	`vcframe.cpp`	Lowering a VC Frame's pages number left widgets hidden on removed pages, still active and saved with the project	Upstream	Medium-high	Medium	App	#88
Q2b	`vcframe.cpp`	The frame's page selector jumped back to "Page 1" when the pages changed, while showing another page (found while testing Q2)	Upstream	High	Very low	App	#88

Noted but not fixed

E7 above.
FunctionEditor::setFadeInSpeed() changes the fade in without keeping the hold. This is the root cause of E10 being easy to reach; changing it affects every editor that uses it.
EFX ignores the Beats tempo type (not reachable in qmlui: the EFX editor has no tempo control).
The qmlui EFX editor and undo remove EFX fixture entries without deleting them (small leak).
Chaser::setTotalDuration() per-step path can divide by zero (v4 UI only).
Scene::slotFixtureRemoved() edits the Scene values without the lock write() holds.
Universe::requestFaderPriority() orders equal-priority faders inconsistently.
ChaserRunner's start offset uses per-step durations for the "Default" duration mode, while playback uses the Chaser's duration.

Bundles for upstream

Each bundle is a fork PR for review first. All are branched from upstream/master, with a regression test or an app test for every fix, so they can go upstream as they are.

Fork PR	Upstream branch	Title	Fixes	Notes
#80	`fix-functiontree-name-clash`	qmlui: fix Function Manager tree when folder and Function share a name	1, 2, 7, 8, A	One-line conflict with mcallegari/qlcplus#2175, now merged upstream, (both add `return` on the same line). Fork PR uses `fork/fix-functiontree-name-clash`, adapted to the fork's Function Manager
#81	`fix-tardis-history`	qmlui: fix Tardis undo/redo history handling	3, 3b, 4
#82	`fix-cuelist-prev-when-stopped`	qmlui: fix Cue List previous/next step when not playing	5
#83	`fix-qmlui-value-bounds`	qmlui: fix 2D fixture distribution, Simple Desk sign extension and ListModel bounds	6, 9, 10, B
#84	`fix-showrunner-shared-functions`	engine: fix Show items sharing a Function and beat items on mid-way start	E1, E9	Fork PR uses `fork/fix-showrunner-shared-functions`, adapted to the fork's tempo map and output hold. The second half of a split Chaser restarts from step 1 (as a separate item does)
#85	`fix-running-function-stale-refs`	engine: fix running Functions using deleted groups and fixtures	E2, E8
#86	`fix-universe-fixture-patching`	engine: keep universe channel setup in step with fixture patching	E3	Changes output behaviour after moving or deleting fixtures, towards what a freshly loaded project does
#87	`fix-small-engine-qmlui`	engine/qmlui: fix random Chasers, Collection/EFX durations and a crash	E4, E5, E6, E10, E11, Q1	Fork PR uses `fork/fix-small-engine-qmlui`, merged with the fork's tempo map ChaserRunner
#88	`fix-vcframe-page-reduction`	qmlui: don't lose VC Frame widgets when reducing the pages number	Q2, Q2b	Widgets are never deleted: the pages can't go below the highest page with widgets