`Scripts.razor` rendered a hash prefix as `@s.SourceHash[..12]…`. `SourceHash`
is a plain nvarchar(64) with no length floor, so any value shorter than 12
characters threw ArgumentOutOfRangeException out of BuildRenderTree — unhandled
in Blazor, which takes the WHOLE page to an HTTP 500, not just the offending
row. Live-reproduced on docker-dev, where two Script rows carry `h1` and
`h-abs-hr200`: /scripts was a hard 500.
New `Components/Shared/DisplayText.Abbreviate(string?, int)`:
- null/blank renders the Admin UI's em-dash placeholder rather than throwing;
- a value already within budget renders verbatim with NO ellipsis, so the
display never implies text that isn't there (the old markup appended "…"
unconditionally, outside the slice — `h1` would have shown as `h1…`);
- a maxLength < 1 is clamped, so a display bug cannot become a page crash.
Applied to every unguarded range-operator slice over a DB-sourced string found
by sweeping the AdminUI for `[..N]`:
Scripts.razor SourceHash (the reported crash)
Certificates.razor Thumbprint (read off the on-disk store)
Deployments.razor x2 RevisionHash
Clusters/ClusterOverview.razor RevisionHash
The other `[..N]` hits are safe and untouched: Guid.ToString("N") slices
(always 32 chars) and the `Length > 60 ? [..60]` ternaries that self-guard.
NOTE — the issue text blamed the docker-dev seed; that was wrong and is
corrected on #504. `seed-clusters.sql` inserts only ServerCluster, ClusterNode
and LdapGroupRoleMapping. The short-hash rows came from earlier live-gate
authoring. A freshly seeded rig is fine; the trigger is any Script row that did
not go through ScriptEdit / UnsTreeService.HashSource — REST-API authored,
hand-inserted, or migrated in.
Tests: 14 new in DisplayTextTests, covering the short/null/blank/clamped cases
and a never-throws sweep over every value x budget combination. AdminUI suite
739/739.
Live-verified on docker-dev (AdminUI has no bUnit): /scripts 500 -> 200 across
both central nodes, rendering `hash=h1` and `hash=h-abs-hr200` in full;
/deployments still truncates 64-char hashes at 12 with the ellipsis;
/certificates and /clusters/MAIN unchanged.
Joseph Doherty
47d148daf9