forms(qml): a tab switch on a ready auto-submit form re-submits it, once per rebuilt control

[Yaraslaut]

Verification: reproduced locally (Windows, MSVC 14.51, Qt 6.11.1, offscreen) with DynamicForm as on master 05222af (the probe ran on a branch that does not touch the code involved). Not seen in CI; no CI case drives it.

withoutAutoSubmit(body) decrements programmaticEdit before its closing revalidate():

function withoutAutoSubmit(body) {
    form.programmaticEdit++
    try { body() } finally { form.programmaticEdit-- }
    form.revalidate()          // runs unsuppressed
}

Every control's Component.onCompleted re-seed goes through it, and a tab switch rebuilds every control of the tab. On a form that is already ready in the default auto-submit mode, each of those closing passes calls controller.submitIfValid. Probe (two tabs, one required integer, typed once, then tab 1 → 0):

QDEBUG : TabResubmit::test_switch() qml: submissions after typing 1 after two tab switches 9
FAIL!  : TabResubmit::test_switch() Compared values are not the same
   Actual   (): 9
   Expected (): 1

The header comment on programmaticEdit states the intent ("repopulating a form is not a user action and must never fire one"); the helper does not keep it. resetFields() escapes only because a cleared form is not ready. #817's prefill() hit the same thing and runs its final revalidate inside the window instead.

Fix: move form.revalidate() into the try block (before the decrement). Closes when the probe above reports 1.

[Yaraslaut]

Triage: triage: valid (with one correction to the issue's scope)

Premise: reproduced on Linux (GCC 16.2.1, Qt 6.11.2, offscreen) on 05222af3, with a QuickTest that wires a counting controller into a two-tab auto-submit form (one required integer, typed once, then tab 1 → 0):

FAIL!  : morph_forms_qml_tests::DynamicFormReseedSubmit::test_tab_switch_does_not_resubmit_a_ready_form() Compared values are not the same
   Actual   (): 9
   Expected (): 1

That is the same 9 the issue reports on Windows/MSVC. The arithmetic matches the code: every field delegate instantiates four controls whose Component.onCompleted goes through withoutAutoSubmit (entry, arrayEntry, boolEntry, notesArea; each exists, hidden, for every field). So one rebuilt field means 4 unsuppressed closing revalidate()s, and two switches make 8 extra calls. Tab switching isn't needed to trigger it; rebuilding the delegates is enough.

Spec vs. code: they don't disagree. docs/spec/forms/forms.md ("Tab switching destroys and rebuilds controls") says re-seeding happens "under the programmaticEdit suppression so re-creating a control never fires the action", and views.md says the same of resetFields(). The helper just doesn't keep that promise. The existing test_tabSwitchRestoresTypedValues runs with controller: null, so it couldn't have seen a submission (invariant 7).

Correction to the issue: "resetFields() escapes only because a cleared form is not ready" is false for a form with no required member. An empty such form is already ready, so the reset's closing revalidate submits it:

FAIL!  : morph_forms_qml_tests::DynamicFormReseedSubmit::test_resetFields_does_not_submit_a_form_that_stays_ready() Compared values are not the same
   Actual   (): 1
   Expected (): 0

That's the exact case views.md describes: opening a row in a CollectionView on an all-optional action fires the action. It has the same root cause and the same fix, so it belongs in this issue rather than a separate one.

Fix direction: valid as written. Moving form.revalidate() inside the suppression window fixes both cases (4/4 in the new suite, full forms_qml_logic green). Nothing in src/ or examples/ relied on the extra submit: every caller of withoutAutoSubmit is a re-seed or resetFields.

Not verified: Windows/macOS after the fix, and whether a form whose only required members are booleans still auto-submits on first load (the boolean seed happens in withoutAutoSubmit; the form's own Component.onCompleted revalidate is unsuppressed). That's arguably a separate question about whether a form should ever submit without any user edit, and I haven't measured it.

Closes when both tests in tst_DynamicFormReseedSubmit.qml pass (tab switch: 1, reset: 0). Re-open if a delegate rebuild or resetFields() is seen reaching submitIfValid again.