feat(extension): probe shows current state before click; v1.0.6

Operator-asked 2026-05-31 (during sidecar synthetic anchor cleanup):
"the add source/subscription button idea to the firefox extension so
it can tell me if a source/artist is added or not and offer an option
to add it if it isn't." Plan tracked in Scribe task #507.

## Backend

- `ExtensionService.probe(url)` — read-only resolution. Reuses
  `_derive` for platform+slug, then 2 SELECTs. Returns one of:
  - `source_match` (exact (artist, platform, url) Source exists)
  - `artist_match` (artist exists, this URL isn't a Source yet;
     collapses the sidecar-synthetic-only case from v26.06.01.0)
  - `new` (neither exists)
  - `unknown_platform` (URL didn't match any artist-page regex)
- `GET /api/extension/probe?url=...` route with `X-Extension-Key`
  auth posture matching `/quick-add-source`. Read-only, side-effect
  free.
- 6 backend tests in tests/test_api_extension.py covering each state
  + auth + invalid URL.

## Extension

- `api.js`: `probeSource(url)` mirroring `quickAddSource` shape.
- `background.js`: `PROBE_SOURCE` + `OPEN_ARTIST_PAGE` handlers. The
  latter strips the `/api` suffix from configured `apiUrl` (placeholder
  format per options.html) and opens `${base}/artist/{slug}` in a new
  tab via `browser.tabs.create`.
- `content-script.js`: probe-first render — on page-load and SPA
  navigation, asks the backend for the URL's state and renders the
  chip in the matching color/copy on FIRST paint instead of flashing
  generic "Add" and updating after. Click handler branches:
  `source_match` → OPEN_ARTIST_PAGE; `artist_match`/`new` → existing
  ADD_AS_SOURCE flow (then re-probes so the chip flips green
  immediately, no wait for next nav).
- `content-script.css`: three state-color modifiers
  (--new, --artist-match, --source-match) on the FC parchment-on-slate
  palette. Sage for already-added, amber for artist-exists, accent
  orange for new.

## Versioning

- `extension/manifest.json` + `extension/package.json` → 1.0.6.
  build.yml's sign-extension job will fire on push to main since no
  `ext-1.0.6` Forgejo/Gitea release exists yet — exercises the
  regenerated AMO keys end-to-end.

## Behavior on the sidecar-synthetic case

Filesystem-imported "Dymkens"-style artist with only a sidecar
synthetic Source: probe returns `artist_match` (not `new`), so the
chip reads "+ Add Patreon source to Dymkens" rather than offering to
recreate the artist. Clicking adds the real Source; existing
`_source_for_sidecar` preference logic (v26.06.01.0) routes future
gallery-dl Posts to the real one.

extension/background/background.js

@@ -259,6 +259,29 @@ browser.runtime.onMessage.addListener(async (msg) => {
         return { error: e.message };
       }
 
+    case 'PROBE_SOURCE':
+      try {
+        return await api.probeSource(msg.url);
+      } catch (e) {
+        return { error: e.message };
+      }
+
+    case 'OPEN_ARTIST_PAGE': {
+      // apiUrl is configured with the /api suffix (see
+      // options/options.html placeholder); the SPA artist route is
+      // /artist/:slug, served from the same origin. Strip /api so the
+      // browser-level URL hits the Vue router, not the JSON API.
+      const base = (api.baseUrl || '').replace(/\/+$/, '').replace(/\/api$/, '');
+      const slug = encodeURIComponent(msg.slug || '');
+      if (!base || !slug) return { error: 'apiUrl or slug missing' };
+      try {
+        await browser.tabs.create({ url: `${base}/artist/${slug}` });
+        return { success: true };
+      } catch (e) {
+        return { error: e.message };
+      }
+    }
+
     default:
       return { error: `Unknown message type: ${msg.type}` };
   }

extension/content/content-script.css

@@ -5,11 +5,26 @@
   background: rgb(20, 23, 26); color: rgb(244, 186, 122);
   font: 500 14px/1.2 system-ui, sans-serif;
   box-shadow: 0 4px 16px rgba(0, 0, 0, 0.4); cursor: pointer;
-  transition: transform 100ms ease;
+  transition: transform 100ms ease, background 150ms ease, color 150ms ease;
 }
 .fc-add-source-btn:hover { transform: translateY(-1px); }
 .fc-add-source-btn:disabled { opacity: 0.6; cursor: wait; }
 
+/* state colors map to the FC palette: parchment-on-slate base,
+   accent-orange for new, sage for already-subscribed, amber-warning for
+   artist-exists-but-source-missing. All readable on the dark base. */
+.fc-add-source-btn--new {
+  background: rgb(20, 23, 26); color: rgb(244, 186, 122);
+}
+.fc-add-source-btn--artist-match {
+  background: rgb(28, 23, 16); color: rgb(255, 200, 120);
+  border: 1px solid rgb(180, 130, 60);
+}
+.fc-add-source-btn--source-match {
+  background: rgb(18, 28, 20); color: rgb(140, 220, 160);
+  border: 1px solid rgb(80, 160, 100);
+}
+
 .fc-toast {
   all: revert;
   position: fixed; bottom: 84px; right: 24px; z-index: 2147483647;

extension/content/content-script.js

@@ -2,6 +2,10 @@
   if (window.__fc_addsource_injected) return;
   window.__fc_addsource_injected = true;
 
+  // Cached probe result for the current URL so click-handlers know which
+  // action to dispatch without round-tripping again.
+  let currentProbe = null;
+
   evaluate();
 
   const reEval = () => evaluate();
@@ -9,38 +13,116 @@
   const origPush = history.pushState;
   history.pushState = function () { origPush.apply(this, arguments); reEval(); };
 
-  function evaluate() {
-    const platform = getPlatformFromUrl(window.location.href);
-    const onArtist = platform && isArtistPage(window.location.href, platform);
-    let btn = document.getElementById('fc-add-source-btn');
-    if (onArtist && !btn) injectButton();
-    else if (!onArtist && btn) btn.remove();
+  async function evaluate() {
+    const url = window.location.href;
+    const platform = getPlatformFromUrl(url);
+    const onArtist = platform && isArtistPage(url, platform);
+    const btn = document.getElementById('fc-add-source-btn');
+    if (!onArtist) {
+      if (btn) btn.remove();
+      currentProbe = null;
+      return;
+    }
+    // On artist pages, ask the backend what state the URL is in BEFORE
+    // injecting the button — so the chip can render the right state on
+    // first paint instead of flashing the generic "Add" copy and
+    // updating afterwards.
+    let probe;
+    try {
+      probe = await browser.runtime.sendMessage({ type: 'PROBE_SOURCE', url });
+    } catch (e) {
+      probe = { error: e?.message || 'probe failed' };
+    }
+    currentProbe = probe;
+    if (probe?.state === 'unknown_platform') {
+      if (btn) btn.remove();
+      return;
+    }
+    renderButton(probe);
   }
 
-  function injectButton() {
-    const btn = document.createElement('button');
-    btn.id = 'fc-add-source-btn';
+  function renderButton(probe) {
+    let btn = document.getElementById('fc-add-source-btn');
+    if (!btn) {
+      btn = document.createElement('button');
+      btn.id = 'fc-add-source-btn';
+      btn.addEventListener('click', onClick);
+      document.body.appendChild(btn);
+    }
+    // Reset state classes so re-renders (SPA navigation) don't stack.
     btn.className = 'fc-add-source-btn';
-    btn.textContent = '+ Add to FabledCurator';
-    btn.addEventListener('click', onClick);
-    document.body.appendChild(btn);
+    btn.classList.add(`fc-add-source-btn--${stateModifier(probe)}`);
+    btn.textContent = labelFor(probe);
+    btn.disabled = false;
+  }
+
+  function stateModifier(probe) {
+    if (!probe || probe.error) return 'new';
+    return ({
+      source_match: 'source-match',
+      artist_match: 'artist-match',
+      new: 'new',
+    })[probe.state] || 'new';
+  }
+
+  function labelFor(probe) {
+    if (!probe || probe.error) return '+ Add to FabledCurator';
+    const platformName = platformDisplayName(probe.platform);
+    const artistName = probe.artist?.name;
+    switch (probe.state) {
+      case 'source_match':
+        return `✓ In FabledCurator · ${platformName}`;
+      case 'artist_match':
+        return `+ Add ${platformName} source to ${artistName || 'artist'}`;
+      case 'new':
+      default:
+        return '+ Add to FabledCurator';
+    }
+  }
+
+  function platformDisplayName(key) {
+    return PLATFORMS[key]?.name || key || '';
   }
 
   async function onClick() {
     const btn = document.getElementById('fc-add-source-btn');
+    if (!btn) return;
     btn.disabled = true;
     const original = btn.textContent;
+    const probe = currentProbe;
+
+    if (probe?.state === 'source_match') {
+      btn.textContent = 'Opening…';
+      try {
+        const r = await browser.runtime.sendMessage({
+          type: 'OPEN_ARTIST_PAGE',
+          slug: probe.artist?.slug,
+        });
+        if (r?.error) showToast(`Error: ${r.error}`, 'error');
+      } catch (e) {
+        showToast(`Error: ${e.message}`, 'error');
+      } finally {
+        btn.disabled = false;
+        btn.textContent = original;
+      }
+      return;
+    }
+
     btn.textContent = 'Adding…';
     try {
       const r = await browser.runtime.sendMessage({
         type: 'ADD_AS_SOURCE',
         url: window.location.href,
       });
-      if (r.error) {
+      if (r?.error) {
         showToast(`Error: ${r.error}`, 'error');
       } else {
         const verb = r.created_source ? 'Added' : 'Already a source for';
         showToast(`${verb} ${r.artist?.name || 'artist'} (${r.source?.platform || ''})`, 'success');
+        // Re-probe so the chip flips green without waiting for the next
+        // navigation.
+        evaluate();
+        return;
       }
     } catch (e) {
       showToast(`Error: ${e.message}`, 'error');

extension/lib/api.js

@@ -83,6 +83,12 @@ class FabledCuratorAPI {
   quickAddSource(url) {
     return this.request('POST', '/extension/quick-add-source', { url });
   }
+  probeSource(url) {
+    // Read-only existence check. Drives the content-script chip's
+    // color/copy BEFORE the operator clicks Add.
+    const qs = new URLSearchParams({ url }).toString();
+    return this.request('GET', `/extension/probe?${qs}`);
+  }
 
   // Connection test = the cheapest read with auth.
   testConnection() {

extension/manifest.json

@@ -1,7 +1,7 @@
 {
   "manifest_version": 3,
   "name": "FabledCurator",
-  "version": "1.0.5",
+  "version": "1.0.6",
   "description": "Export cookies from supported platforms to FabledCurator and add creators as sources in one click.",
 
   "browser_specific_settings": {

extension/package.json

@@ -1,6 +1,6 @@
 {
   "name": "fabledcurator-extension",
-  "version": "1.0.5",
+  "version": "1.0.6",
   "private": true,
   "description": "Firefox extension for FabledCurator",
   "scripts": {