spikerj/spikersoft-issues
1
0
Fork 0
Code Issues 196 Pull Requests Actions Packages Projects Releases Wiki Activity

[Bug][Art Studio] Display images never cache across visits — backend half of #784 (presigned display URL) was never built #804

New Issue
Open
opened 2026-07-22 23:02:21 +00:00 by spikerj · 1 comment
spikerj commented 2026-07-22 23:02:21 +00:00
Owner
Copy Link
Copy Source

Summary

Art Studio display images (my-assets card thumbnails, gallery, viewer strip, full-size views) re-download in full on every page visit — nothing caches them in the browser, CDN, or object store. The /tools/art-studio page loads images slowly on every visit even though art assets are immutable once generated.

Root cause — #784 is half-shipped

The presigned-display-URL feature #784 landed on the frontend but its backend half was never built.

  • Frontend half MERGED (spikersoft-angular PR #518, feat/784-presigned-artifact-display): every display path calls ArtStudioService.fetchArtifactDisplayUrl, which prefers a backend-minted artifact.url (a plain, browser-cacheable <img src>) and only falls back to an authenticated blob→objectURL fetch when url is absent.
    • libraries/features/art-studio/src/lib/art-studio.service.ts:653 — fetchArtifactDisplayUrl → artifact.url ?? fetchArtifactObjectUrl(...)
  • Backend half NEVER BUILT. On master, ArtAssetArtifactRef (SpikerSoft.Data/Mongos/ArtStudio/ArtAsset.cs:354-378) has no url field and no handler mints one. So artifact.url is always undefined in prod → every image takes the fallback path.

The fallback path is fundamentally uncacheable:

  • Bytes are fetched through the authenticated API as a blob and wrapped in URL.createObjectURL(...) — object URLs are memory-only, non-HTTP-cacheable, and the shell revokes them on page-leave (art-studio-shell.component.ts → revokeAllThumbnails in ngOnDestroy).
  • The download endpoint sets no Cache-Control (ArtStudioController.cs:342-369 — File(stream, contentType, fileName), which also emits Content-Disposition: attachment).
  • The stored MinIO objects carry no Cache-Control either (S3ArtAssetFileStore.UploadCoreAsync:30-55 — no CacheControl on the PutObjectRequest).

Additionally, card thumbnails resolve to the same full-resolution PNG as the detail view — there is no small derivative (ArtAssetArtifactSelection.PickThumbnail returns the full concept image ref). So grids download full-res PNGs, N at a time, every visit. (The small-derivative fix is tracked in the companion AVIF ticket.)

Proposed fix

Mirror the proven BookController cover pattern (SpikerSoft.Api/Domain/Books/BookController.cs:77-119 ToDtoWithCover + IObjectStore.GetPresignedUrl, SpikerSoft.Storage/S3ObjectStore.cs:90-97):

  1. Mint artifact.url on the Art Studio artifact DTOs (list / get / gallery list + detail) as a presigned MinIO URL, applied per-response after any cache layer. Preserves authz (server only mints for authorized callers — private my-assets stay private, approved gallery stays approved). Local dev (Storage:UseS3 off) leaves url null → the existing fallback still works.

  2. Make it cache across visits (the actual complaint). A per-request presign like BookController re-signs with a fresh Expires each response → the URL string changes each visit → browser cache miss. Since art-artifact objects are immutable and content-keyed:

    • Set Cache-Control: public, max-age=31536000, immutable on objects at PUT (S3ArtAssetFileStore), and backfill existing objects.
    • Mint the presigned URL with a stable / rounded expiry (bucket the Expires timestamp to a fixed boundary) so repeated mints for the same object yield a byte-identical URL within the window → real browser cache hits. (Alternatively use a response-cache-control override on the presign.)

Acceptance criteria

  • A second visit to /tools/art-studio serves every already-seen image from browser cache (from-cache / 304 — no full MinIO re-download).
  • artifact.url present on list/get/gallery artifact refs when S3 is on; null in local dev with the fallback intact.
  • Private assets remain authz-gated; no public-bucket exposure.
  • Cache-Control: immutable present on both new and backfilled art-artifact objects.

References

  • Frontend half already merged: spikersoft-angular PR #518 (#784)
  • Template: BookController presigned covers (#618 / #719)
  • Companion: AVIF display derivatives + real small card thumbnail (see linked ticket)
## Summary Art Studio display images (my-assets card thumbnails, gallery, viewer strip, full-size views) re-download in full on **every** page visit — nothing caches them in the browser, CDN, or object store. The `/tools/art-studio` page loads images slowly on every visit even though art assets are immutable once generated. ## Root cause — `#784` is half-shipped The presigned-display-URL feature **#784** landed on the frontend but its backend half was never built. - **Frontend half MERGED** (spikersoft-angular PR #518, `feat/784-presigned-artifact-display`): every display path calls `ArtStudioService.fetchArtifactDisplayUrl`, which prefers a backend-minted `artifact.url` (a plain, browser-cacheable `<img src>`) and only falls back to an authenticated blob→objectURL fetch when `url` is absent. - `libraries/features/art-studio/src/lib/art-studio.service.ts:653` — `fetchArtifactDisplayUrl` → `artifact.url ?? fetchArtifactObjectUrl(...)` - **Backend half NEVER BUILT.** On master, `ArtAssetArtifactRef` (`SpikerSoft.Data/Mongos/ArtStudio/ArtAsset.cs:354-378`) has no `url` field and no handler mints one. So `artifact.url` is **always undefined in prod** → every image takes the fallback path. The fallback path is fundamentally uncacheable: - Bytes are fetched through the **authenticated API** as a blob and wrapped in `URL.createObjectURL(...)` — object URLs are memory-only, non-HTTP-cacheable, and the shell **revokes them on page-leave** (`art-studio-shell.component.ts` → `revokeAllThumbnails` in `ngOnDestroy`). - The download endpoint sets **no `Cache-Control`** (`ArtStudioController.cs:342-369` — `File(stream, contentType, fileName)`, which also emits `Content-Disposition: attachment`). - The stored MinIO objects carry **no `Cache-Control`** either (`S3ArtAssetFileStore.UploadCoreAsync:30-55` — no `CacheControl` on the `PutObjectRequest`). Additionally, card thumbnails resolve to the **same full-resolution PNG** as the detail view — there is no small derivative (`ArtAssetArtifactSelection.PickThumbnail` returns the full concept image ref). So grids download full-res PNGs, N at a time, every visit. *(The small-derivative fix is tracked in the companion AVIF ticket.)* ## Proposed fix Mirror the proven BookController cover pattern (`SpikerSoft.Api/Domain/Books/BookController.cs:77-119` `ToDtoWithCover` + `IObjectStore.GetPresignedUrl`, `SpikerSoft.Storage/S3ObjectStore.cs:90-97`): 1. **Mint `artifact.url`** on the Art Studio artifact DTOs (list / get / gallery list + detail) as a presigned MinIO URL, applied per-response *after* any cache layer. Preserves authz (server only mints for authorized callers — private my-assets stay private, approved gallery stays approved). Local dev (`Storage:UseS3` off) leaves `url` null → the existing fallback still works. 2. **Make it cache across visits** (the actual complaint). A per-request presign like BookController re-signs with a fresh `Expires` each response → the URL string changes each visit → browser cache miss. Since art-artifact objects are immutable and content-keyed: - Set `Cache-Control: public, max-age=31536000, immutable` on objects at PUT (`S3ArtAssetFileStore`), and backfill existing objects. - Mint the presigned URL with a **stable / rounded expiry** (bucket the `Expires` timestamp to a fixed boundary) so repeated mints for the same object yield a byte-identical URL within the window → real browser cache hits. (Alternatively use a `response-cache-control` override on the presign.) ## Acceptance criteria - A second visit to `/tools/art-studio` serves every already-seen image from browser cache (from-cache / 304 — no full MinIO re-download). - `artifact.url` present on list/get/gallery artifact refs when S3 is on; null in local dev with the fallback intact. - Private assets remain authz-gated; no public-bucket exposure. - `Cache-Control: immutable` present on both new and backfilled art-artifact objects. ## References - Frontend half already merged: spikersoft-angular PR #518 (`#784`) - Template: BookController presigned covers (`#618` / `#719`) - Companion: AVIF display derivatives + real small card thumbnail (see linked ticket)
spikerj commented 2026-07-29 15:49:32 +00:00
Author
Owner
Copy Link
Copy Source

Audited against origin/master — 3 of 4 acceptance criteria met; AC4 shipped as the ticket's own stated alternative. Leaving open as a judgement call for you rather than closing it unilaterally.

AC1 — stable URL: met. ArtStudioController.cs:113-114 (ArtifactUrlBucket = 1h, ArtifactUrlTtl = 2h) plus :167-178 StablePresignedUrl, which memoizes per (objectKey, bucket) in IMemoryCache and expires on the bucket boundary. Within the window the URL is byte-identical, which is exactly the bucketed-Expires approach the ticket prescribed.

AC2 — url on list/get/gallery refs, null in local dev: met. :120-146 MintArtifactUrls, guarded so it only runs when the keyed store exists (Storage:UseS3).

AC3 — authorization preserved: met. URLs are minted after the handler's authorization decision and never persisted (:94-99).

AC4 — Cache-Control: immutable on art-artifact objects: not met as worded.

  • No object-level header at PUT: S3ArtAssetFileStore.cs:36-55 builds PutObjectRequest with no CacheControl. git grep -n "CacheControl" origin/master -- SpikerSoft.Data SpikerSoft.EventHandlers.ArtPipeProcessor → no matches.
  • No backfill of existing objects — no tool, no commit.

What shipped instead is the alternative this ticket itself names: a signed response-cache-control override — ArtStudioController.cs:115 PresignedCacheControl = "private, max-age=3600", applied at S3ObjectStore.cs:90-101.

The call is yours. That delivers the user-visible outcome (images cache across visits), so closing this is defensible. The practical ceiling worth knowing: caching holds for one hour, then the URL rotates with the bucket and the browser entry expires — so it's a 1-hour cache, not immutable. If that's fine, close it; if you want true immutability and the benefit for already-stored objects, the remaining work is the PUT-time header plus a backfill.

Audited against `origin/master` — **3 of 4 acceptance criteria met; AC4 shipped as the ticket's own stated alternative.** Leaving open as a judgement call for you rather than closing it unilaterally. **AC1 — stable URL: met.** `ArtStudioController.cs:113-114` (`ArtifactUrlBucket = 1h`, `ArtifactUrlTtl = 2h`) plus `:167-178` `StablePresignedUrl`, which memoizes per `(objectKey, bucket)` in `IMemoryCache` and expires on the bucket boundary. Within the window the URL is byte-identical, which is exactly the bucketed-`Expires` approach the ticket prescribed. **AC2 — `url` on list/get/gallery refs, null in local dev: met.** `:120-146` `MintArtifactUrls`, guarded so it only runs when the keyed store exists (`Storage:UseS3`). **AC3 — authorization preserved: met.** URLs are minted after the handler's authorization decision and never persisted (`:94-99`). **AC4 — `Cache-Control: immutable` on art-artifact objects: not met as worded.** - No object-level header at PUT: `S3ArtAssetFileStore.cs:36-55` builds `PutObjectRequest` with no `CacheControl`. `git grep -n "CacheControl" origin/master -- SpikerSoft.Data SpikerSoft.EventHandlers.ArtPipeProcessor` → **no matches**. - No backfill of existing objects — no tool, no commit. **What shipped instead** is the alternative this ticket itself names: a signed `response-cache-control` override — `ArtStudioController.cs:115` `PresignedCacheControl = "private, max-age=3600"`, applied at `S3ObjectStore.cs:90-101`. **The call is yours.** That delivers the user-visible outcome (images cache across visits), so closing this is defensible. The practical ceiling worth knowing: caching holds for one hour, then the URL rotates with the bucket and the browser entry expires — so it's a 1-hour cache, not `immutable`. If that's fine, close it; if you want true immutability and the benefit for already-stored objects, the remaining work is the PUT-time header plus a backfill.
Sign in to join this conversation.
No Branch/Tag Specified
Branches Tags
Labels
Clear labels
agentic
Actionable surfaced by the agentic architecture & security review
 bug
Something is not working
 duplicate
This issue or pull request already exists
 enhancement
New feature
 help wanted
Need some help
 invalid
Something is wrong
 question
More information is needed
 sonarqube
Code quality issue surfaced by SonarQube (bug / code smell)
 wontfix
This won't be fixed
No labels
Milestone
No items
No Milestone
Projects
Clear projects
No projects
Assignees
Clear assignees
spikerj (Joseph Spiker)
No Assignees
1 Participants
Notifications
Due Date
No due date set.
Dependencies

No dependencies set.

Reference: spikerj/spikersoft-issues#804