The modernized Execute Tests screen (gui/templates/execute/execTest.html + api/execute/index.php) showed the version number of a test case but offered no way to select or execute an older linked version. A test plan that has two versions of the same test case linked (e.g. v1 and v2) only ever listed the latest version: the BFF tcList deliberately collapsed the linked version set ($latestByTcase), so the older version was unreachable from the UI entirely — a regression vs. the legacy execution tree, where every linked version appears as its own tree node and can be opened/executed.

1. api/execute/index.php ?action=tcList selected all linked versions in SQL (lines 476-487) but then discarded everything but the newest: lines 492-502 built $latestByTcase keeping only the row with max TCV.version, and every downstream block (execMap lines 504-535, pathMap lines 538-553, the item loop at line 562) operated on that single row. With testplan_tcversions holding both v1 (tcversion 13) and v2 (tcversion 15), the API returned only {tcversion_id: 15, version: 2}.
2. gui/templates/execute/execTest.html renderForm() showed the version number in the form meta (v + v.number, line ~397) and serialized current.version.id / current.version.number on save, but there was no UI element to pick a different linked version and no versions[] payload to feed one.

The backend execution path was already version-agnostic and correct — ?action=tcDetails and ?action=save both handle an arbitrary linked tcversion_id (verified: saving against v1 writes the execution row correctly). The entire regression lived in the tcList collapse plus the missing selector.

Backend — api/execute/index.php ?action=tcList:

• Replace the latest-only collapse with a per-test-case grouping $tcGroups. The list/display row still uses the latest version (status badge, last execution column unchanged for existing callers), but the payload now also carries versions[] with every linked version ({tcversion_id, version, active, last_execution}), newest first (the SQL already orders by TCV.version DESC).
• execMap (last execution on the selected build/platform) is computed over all linked version ids instead of just the latest, so each version row gets its own last_execution.

Frontend — gui/templates/execute/execTest.html:

• openCase() copies the list item's versions[] into current.versions so the detail form knows which versions are linked.
• renderForm() renders a Version <select> (plus a "Switch version" button) whenever current.versions.length > 1. Options are v<n> (suffixed (inactive) for non-active versions). In read-only mode the selector is shown but the switch button is omitted.
• New switchVersion() re-fetches tcDetails for the chosen version (after a confirm dialog echoing that unsaved changes are lost) and re-renders; the existing save/partial-save paths already serialize current.version.id/.number, so an execution now targets the selected older version.

i18n: added exe.version, exe.inactiveVersion, exe.switchVersion, exe.confirmSwitchVersion to all 10 locale bundles (de,en,es,fr,it,ja,pt,ro,ru,zh).

• Minimal: tcList changed in place (reuses the existing SQL and the already-version-aware tcDetails/save routes); no DB/schema change, no new endpoint. testplan_tcversions has no unique key on (testplan_id, tcversion_id), so multiple linked versions coexist exactly as legacy expects.
• Non-breaking list: keeping the latest version as the row keeps the search/filter/status-badge behavior of the screen identical for single-version test cases (regression check: versions.length === 1 renders no selector at all).
• Matches legacy UX: legacy exposes versions through the tree; the in-form selector is the direct Dashio equivalent.
• Alternatives rejected: listing one row per version would duplicate rows in the left list (name/status repeated) and change the search/badge logic; auto-picking the newest linked version on open (legacy default) is already the behavior and would not have fixed the reported symptom.

• api/execute/index.php — tcList: $tcGroups grouping + versions[].
• gui/templates/execute/execTest.html — version switcher + switchVersion().
• gui/templates/i18n/{de,en,es,fr,it,ja,pt,ro,ru,zh}.json — 4 new exe.* keys per bundle.

• c164d2e14 — fix(execute): keep all linked TC versions selectable/executable (Refs #794)
• c2d85c326 — test(execute): attach issue #794 regression screenshots (Refs #794)

Version selector on the modernized Execute screen (v2 selected, v1 available):

After switching to v1 and executing it (prior PASSED execution + exec history for v1 shown):

#	Case	Result
1	tcList on a multi-version plan shows versions[] with all linked versions (newest first); list row = latest	PASS
2	Per-version last_execution present in versions[]	PASS
3	Version selector rendered for a multi-version test case	PASS
4	Switch to the older version loads its summary/steps/prior execution	PASS
5	Saving an execution on the older version writes executions with its tcversion_id	PASS
6	Single-version test cases show NO selector (flow unchanged)	PASS
7	Read-only mode hides the switch button	PASS (guard review)
8	All 10 i18n bundles valid JSON	PASS

Verified 2026-08-30 with fixture tmp/fixture_794.php (project VERS794, test case TCVers794 with v1/v2 linked), headless Chrome at http://localhost:8082, admin/admin. Event Viewer: no new Error/Warning rows from the screen flow.