diff --git a/public/app.js b/public/app.js
index a1917d2..ce41f11 100644
--- a/public/app.js
+++ b/public/app.js
@@ -278,7 +278,7 @@ function statusBadge(status) {
 function renderStoreCard(repo) {
   const owner = escape(repo.owner?.login || "");
   const isOfficial = (repo.owner?.login || "").toLowerCase() === "corvidlabs";
-  const topics = (repo.topics || []).slice(0, 5);
+  const topics = (repo.topics || []).filter((t) => t !== "fledge-plugin" && t !== "fledge-template" && t !== "fledge").slice(0, 5);
   const installed = isInstalled(repo.full_name);
   const fullEsc = escape(repo.full_name || "");
   const installedPlugin = installedBySource.get((repo.full_name || "").toLowerCase());
@@ -290,6 +290,19 @@ function renderStoreCard(repo) {
     : `<button class="btn btn-sm btn-outline" data-action="readme" data-owner="${escape(repo.owner?.login)}" data-repo="${escape(repo.name)}">Readme</button>
        <button class="btn btn-sm" data-action="install" data-source="${fullEsc}">Install</button>`;
 
+  const lang = repo.language || "";
+  const topicTagsHtml = topics.map((t) => {
+    const active = storeFilters.topics.has(t.toLowerCase());
+    return `<button type="button" class="topic-tag${active ? " active" : ""}" data-action="toggle-topic" data-value="${escape(t)}">${escape(t)}</button>`;
+  }).join("");
+
+  const langStat = lang
+    ? `<button type="button" class="store-card-stat store-card-stat-link" data-action="set-language" data-value="${escape(lang)}">${escape(lang)}</button>`
+    : "";
+  const ownerLink = repo.owner?.login
+    ? `<button type="button" class="store-card-author-link" data-action="set-owner" data-value="${escape(repo.owner.login)}">${owner}</button>`
+    : owner;
+
   return `
     <div class="store-card${installed ? " store-card-installed" : ""}">
       <div class="store-card-header">
@@ -299,7 +312,7 @@ function renderStoreCard(repo) {
             <a href="${escape(repo.html_url)}" target="_blank" rel="noopener">${escape(repo.name)}</a>
           </div>
           <div class="store-card-author">
-            ${owner}
+            ${ownerLink}
             ${isOfficial ? '<span class="badge badge-official">official</span>' : ""}
             ${installed ? '<span class="badge badge-installed">installed</span>' : ""}
           </div>
@@ -308,12 +321,12 @@ function renderStoreCard(repo) {
       <div class="store-card-desc">${escape(repo.description || "No description")}</div>
       <div class="store-card-topics">
         ${typeBadge(repo.topics)}
-        ${topics.filter((t) => t !== "fledge-plugin" && t !== "fledge-template").map((t) => `<span class="topic-tag">${escape(t)}</span>`).join("")}
+        ${topicTagsHtml}
       </div>
       <div class="store-card-footer">
         <div class="store-card-stats">
           <span class="store-card-stat">${repo.stargazers_count || 0} stars</span>
-          ${repo.language ? `<span class="store-card-stat">${escape(repo.language)}</span>` : ""}
+          ${langStat}
           <span class="store-card-stat">${timeAgo(repo.updated_at)}</span>
         </div>
         <div class="store-card-actions">${actions}</div>
@@ -557,10 +570,180 @@ function renderDoctor(report) {
   return `${summary}${sections}`;
 }
 
+// --- Store filter state ---
+
+const storeFilters = {
+  category: "all",
+  q: "",
+  language: "",
+  owner: "",
+  license: "",
+  topics: new Set(),
+};
+
+let storeFacets = { topics: [], languages: [], owners: [], licenses: [] };
+
+const FACET_INITIAL_LIMIT = 8;
+const facetExpanded = { topics: false, languages: false, owners: false, licenses: false };
+
+function buildStoreUrl() {
+  const params = new URLSearchParams({ category: storeFilters.category });
+  if (storeFilters.q) params.set("q", storeFilters.q);
+  if (storeFilters.language) params.set("language", storeFilters.language);
+  if (storeFilters.owner) params.set("owner", storeFilters.owner);
+  if (storeFilters.license) params.set("license", storeFilters.license);
+  for (const t of storeFilters.topics) params.append("topic", t);
+  return `/github/browse?${params}`;
+}
+
+function activeFilterCount() {
+  let n = 0;
+  if (storeFilters.q) n += 1;
+  if (storeFilters.language) n += 1;
+  if (storeFilters.owner) n += 1;
+  if (storeFilters.license) n += 1;
+  n += storeFilters.topics.size;
+  return n;
+}
+
+function clearStoreFilters() {
+  storeFilters.q = "";
+  storeFilters.language = "";
+  storeFilters.owner = "";
+  storeFilters.license = "";
+  storeFilters.topics.clear();
+  const search = $("#store-search");
+  if (search) search.value = "";
+  loaders.store();
+}
+
+function toggleTopic(topic) {
+  const key = String(topic || "").toLowerCase();
+  if (!key) return;
+  if (storeFilters.topics.has(key)) storeFilters.topics.delete(key);
+  else storeFilters.topics.add(key);
+  loaders.store();
+}
+
+function setSingleFilter(key, value) {
+  if (key !== "language" && key !== "owner" && key !== "license") return;
+  const next = String(value || "");
+  storeFilters[key] = storeFilters[key] === next ? "" : next;
+  loaders.store();
+}
+
+function renderActiveFilters() {
+  const wrap = $("#store-active-filters");
+  if (!wrap) return;
+  const chips = [];
+  if (storeFilters.q) {
+    chips.push({ kind: "q", label: storeFilters.q, onRemove: "clear-q" });
+  }
+  for (const t of storeFilters.topics) {
+    chips.push({ kind: "topic", label: t, onRemove: "toggle-topic", value: t });
+  }
+  if (storeFilters.language) {
+    chips.push({ kind: "lang", label: storeFilters.language, onRemove: "set-language", value: storeFilters.language });
+  }
+  if (storeFilters.owner) {
+    chips.push({ kind: "owner", label: storeFilters.owner, onRemove: "set-owner", value: storeFilters.owner });
+  }
+  if (storeFilters.license) {
+    chips.push({ kind: "license", label: storeFilters.license, onRemove: "set-license", value: storeFilters.license });
+  }
+  if (chips.length === 0) {
+    wrap.innerHTML = "";
+    return;
+  }
+  wrap.innerHTML = chips.map((c) => `
+    <button type="button" class="active-filter-chip" data-action="${c.onRemove}"${c.value != null ? ` data-value="${escape(c.value)}"` : ""} title="Remove filter">
+      <span class="active-filter-chip-key">${c.kind}</span>
+      <span>${escape(c.label)}</span>
+      <span class="active-filter-chip-x">&times;</span>
+    </button>`).join("");
+}
+
+function renderFilterGroup(label, key, options, activeSet, action) {
+  if (!options || options.length === 0) {
+    return `
+      <div class="filter-group">
+        <div class="filter-group-name">${label}</div>
+        <div class="filter-group-empty">— none —</div>
+      </div>`;
+  }
+  const expanded = facetExpanded[key];
+  const visible = expanded ? options : options.slice(0, FACET_INITIAL_LIMIT);
+  const remainder = options.length - visible.length;
+  const items = visible.map((opt) => {
+    const lower = opt.value.toLowerCase();
+    const active = activeSet ? activeSet(lower, opt.value) : false;
+    return `
+      <button type="button" class="filter-option${active ? " active" : ""}" data-action="${action}" data-value="${escape(opt.value)}">
+        <span class="filter-option-label">${escape(opt.value)}</span>
+        <span class="filter-option-count">${opt.count}</span>
+      </button>`;
+  }).join("");
+
+  const toggle = options.length > FACET_INITIAL_LIMIT
+    ? `<button type="button" class="filter-group-toggle" data-action="toggle-facet" data-facet="${key}">${expanded ? "Show less" : `Show ${remainder} more`}</button>`
+    : "";
+
+  return `
+    <div class="filter-group">
+      <div class="filter-group-name">${label}</div>
+      ${items}
+      ${toggle}
+    </div>`;
+}
+
+function renderFilterRail() {
+  const wrap = $("#filter-groups");
+  if (!wrap) return;
+  const html = [
+    renderFilterGroup(
+      "Topic",
+      "topics",
+      storeFacets.topics || [],
+      (lower) => storeFilters.topics.has(lower),
+      "toggle-topic",
+    ),
+    renderFilterGroup(
+      "Language",
+      "languages",
+      storeFacets.languages || [],
+      (_, raw) => storeFilters.language === raw,
+      "set-language",
+    ),
+    renderFilterGroup(
+      "Author",
+      "owners",
+      storeFacets.owners || [],
+      (_, raw) => storeFilters.owner.toLowerCase() === raw.toLowerCase(),
+      "set-owner",
+    ),
+    renderFilterGroup(
+      "License",
+      "licenses",
+      storeFacets.licenses || [],
+      (_, raw) => storeFilters.license === raw,
+      "set-license",
+    ),
+  ].join("");
+  wrap.innerHTML = html;
+
+  const clear = $("#clear-filters");
+  if (clear) clear.hidden = activeFilterCount() === 0;
+}
+
+function renderResultCount(total) {
+  const el = $("#store-result-count");
+  if (!el) return;
+  if (total == null) { el.textContent = ""; return; }
+  el.textContent = `${total} result${total === 1 ? "" : "s"}`;
+}
+
 // --- Page loaders ---
 
-let currentCategory = "all";
-let currentSearch = "";
 const loaded = {};
 
 const loaders = {
@@ -578,17 +761,23 @@ const loaders = {
   async store() {
     const grid = $("#store-grid");
     html(grid, '<div class="loading">Loading packages from GitHub</div>');
+    renderActiveFilters();
+    renderResultCount(null);
     await refreshInstalled();
-    const params = new URLSearchParams({ category: currentCategory });
-    if (currentSearch) params.set("q", currentSearch);
-    const data = await api(`/github/browse?${params}`);
+    const data = await api(buildStoreUrl());
     if (data?.error) {
+      storeFacets = { topics: [], languages: [], owners: [], licenses: [] };
+      renderFilterRail();
       html(grid, renderError(data.error));
       return;
     }
     const items = data?.items || [];
+    storeFacets = data?.facets || { topics: [], languages: [], owners: [], licenses: [] };
+    renderFilterRail();
+    renderActiveFilters();
+    renderResultCount(typeof data?.total === "number" ? data.total : items.length);
     if (items.length === 0) {
-      html(grid, renderEmpty("No packages found. Try a different search or category."));
+      html(grid, renderEmpty("No packages match these filters. Try removing one or clearing all."));
     } else {
       html(grid, items.map(renderStoreCard).join(""));
     }
@@ -841,6 +1030,23 @@ document.addEventListener("click", (e) => {
   else if (action === "run-lane") runLane(btn.dataset.name, btn);
   else if (action === "open-repo") openRepo();
   else if (action === "close-output") $("#run-output-card")?.classList.add("hidden");
+  else if (action === "toggle-topic") toggleTopic(btn.dataset.value);
+  else if (action === "set-language") setSingleFilter("language", btn.dataset.value);
+  else if (action === "set-owner") setSingleFilter("owner", btn.dataset.value);
+  else if (action === "set-license") setSingleFilter("license", btn.dataset.value);
+  else if (action === "clear-q") {
+    storeFilters.q = "";
+    const search = $("#store-search");
+    if (search) search.value = "";
+    loaders.store();
+  }
+  else if (action === "toggle-facet") {
+    const key = btn.dataset.facet;
+    if (key && key in facetExpanded) {
+      facetExpanded[key] = !facetExpanded[key];
+      renderFilterRail();
+    }
+  }
 });
 
 // Nav links
@@ -856,7 +1062,7 @@ $$(".category-tabs .tab").forEach((tab) => {
   tab.addEventListener("click", () => {
     $$(".category-tabs .tab").forEach((t) => t.classList.remove("active"));
     tab.classList.add("active");
-    currentCategory = tab.dataset.category;
+    storeFilters.category = tab.dataset.category;
     loaders.store();
   });
 });
@@ -871,19 +1077,35 @@ $$(".section-tab").forEach((tab) => {
   });
 });
 
-// Store search
-$("#store-search-btn").addEventListener("click", () => {
-  currentSearch = $("#store-search").value.trim();
+// Store search — debounced live filter; Enter forces an immediate run.
+let searchDebounce = null;
+
+function commitStoreSearch() {
+  const next = $("#store-search").value.trim();
+  if (next === storeFilters.q) return;
+  storeFilters.q = next;
   loaders.store();
+}
+
+$("#store-search").addEventListener("input", () => {
+  if (searchDebounce) clearTimeout(searchDebounce);
+  searchDebounce = setTimeout(commitStoreSearch, 300);
 });
 
 $("#store-search").addEventListener("keydown", (e) => {
   if (e.key === "Enter") {
-    currentSearch = $("#store-search").value.trim();
-    loaders.store();
+    e.preventDefault();
+    if (searchDebounce) clearTimeout(searchDebounce);
+    commitStoreSearch();
+  } else if (e.key === "Escape" && $("#store-search").value) {
+    $("#store-search").value = "";
+    if (searchDebounce) clearTimeout(searchDebounce);
+    commitStoreSearch();
   }
 });
 
+$("#clear-filters")?.addEventListener("click", () => clearStoreFilters());
+
 // Modal close
 $(".modal-backdrop")?.addEventListener("click", () => {
   $("#readme-modal")?.classList.add("hidden");
diff --git a/public/index.html b/public/index.html
index cba88c3..41a33d4 100644
--- a/public/index.html
+++ b/public/index.html
@@ -68,19 +68,33 @@
       <header class="page-head">
         <div class="page-kicker">Store</div>
         <h1 class="page-title">Browse Packages</h1>
-        <p class="page-lede">Discover plugins and templates from the fledge ecosystem.</p>
+        <p class="page-lede">Discover plugins and templates from the fledge ecosystem. Filter by topic, language, or author.</p>
       </header>
       <div class="toolbar">
         <input type="text" id="store-search" placeholder="Search plugins and templates..." class="search-input">
-        <button id="store-search-btn" class="btn">Search</button>
       </div>
       <div class="category-tabs">
         <button class="tab active" data-category="all">All</button>
         <button class="tab" data-category="plugins">Plugins</button>
         <button class="tab" data-category="templates">Templates</button>
       </div>
-      <div id="store-grid" class="store-grid">
-        <div class="loading">Loading packages from GitHub</div>
+      <div class="store-layout">
+        <aside class="filter-rail" id="filter-rail">
+          <div class="filter-rail-header">
+            <span class="filter-rail-title">Filters</span>
+            <button class="btn-link" id="clear-filters" hidden>Clear all</button>
+          </div>
+          <div id="filter-groups"></div>
+        </aside>
+        <div class="store-results">
+          <div class="store-results-header">
+            <div id="store-active-filters" class="active-filters"></div>
+            <div class="store-result-count" id="store-result-count"></div>
+          </div>
+          <div id="store-grid" class="store-grid">
+            <div class="loading">Loading packages from GitHub</div>
+          </div>
+        </div>
       </div>
     </div>
 
diff --git a/public/style.css b/public/style.css
index e8f573c..4ee4e59 100644
--- a/public/style.css
+++ b/public/style.css
@@ -412,11 +412,211 @@ h3 {
 .installed-section { display: none; }
 .installed-section.active { display: block; }
 
+/* === STORE LAYOUT === */
+
+.store-layout {
+  display: grid;
+  grid-template-columns: 200px 1fr;
+  gap: 1.5rem;
+  align-items: start;
+}
+
+.filter-rail {
+  position: sticky;
+  top: var(--content-pad);
+  display: flex;
+  flex-direction: column;
+  gap: 1.1rem;
+  padding-right: 0.25rem;
+  max-height: calc(100vh - var(--content-pad) * 2);
+  overflow-y: auto;
+}
+
+.filter-rail-header {
+  display: flex;
+  align-items: baseline;
+  justify-content: space-between;
+  padding-bottom: 0.5rem;
+  border-bottom: 1px solid var(--border);
+}
+
+.filter-rail-title {
+  font-family: var(--font-mono);
+  font-size: 0.6rem;
+  font-weight: 600;
+  letter-spacing: 0.14em;
+  text-transform: uppercase;
+  color: var(--text-muted);
+}
+
+.btn-link {
+  background: none;
+  border: none;
+  padding: 0;
+  font-family: var(--font-mono);
+  font-size: 0.6rem;
+  letter-spacing: 0.06em;
+  text-transform: uppercase;
+  color: var(--text-faint);
+  transition: color var(--transition);
+}
+
+.btn-link:hover { color: var(--accent); }
+
+.filter-group {
+  display: flex;
+  flex-direction: column;
+  gap: 0.25rem;
+}
+
+.filter-group-name {
+  font-family: var(--font-mono);
+  font-size: 0.55rem;
+  font-weight: 600;
+  letter-spacing: 0.16em;
+  text-transform: uppercase;
+  color: var(--text-faint);
+  margin-bottom: 0.15rem;
+}
+
+.filter-option {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 0.5rem;
+  background: none;
+  border: none;
+  padding: 0.25rem 0.4rem;
+  margin: 0 -0.4rem;
+  font-family: var(--font-mono);
+  font-size: 0.7rem;
+  color: var(--text-secondary);
+  border-radius: 3px;
+  text-align: left;
+  width: calc(100% + 0.8rem);
+  transition: color var(--transition), background var(--transition);
+}
+
+.filter-option:hover {
+  color: var(--text-primary);
+  background: var(--bg-hover);
+}
+
+.filter-option.active {
+  color: var(--accent);
+  background: var(--accent-subtle);
+}
+
+.filter-option-label {
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.filter-option-count {
+  color: var(--text-faint);
+  font-size: 0.6rem;
+  flex-shrink: 0;
+}
+
+.filter-option.active .filter-option-count { color: var(--accent); }
+
+.filter-group-empty {
+  font-family: var(--font-mono);
+  font-size: 0.62rem;
+  color: var(--text-faint);
+  padding: 0.2rem 0;
+}
+
+.filter-group-toggle {
+  background: none;
+  border: none;
+  padding: 0.2rem 0;
+  font-family: var(--font-mono);
+  font-size: 0.6rem;
+  color: var(--text-faint);
+  letter-spacing: 0.04em;
+  text-align: left;
+  transition: color var(--transition);
+}
+
+.filter-group-toggle:hover { color: var(--accent); }
+
+.store-results {
+  min-width: 0;
+  display: flex;
+  flex-direction: column;
+  gap: 0.85rem;
+}
+
+.store-results-header {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  gap: 0.85rem;
+  flex-wrap: wrap;
+  min-height: 1.4rem;
+}
+
+.active-filters {
+  display: flex;
+  gap: 0.3rem;
+  flex-wrap: wrap;
+  flex: 1;
+  min-width: 0;
+}
+
+.active-filter-chip {
+  display: inline-flex;
+  align-items: center;
+  gap: 0.35rem;
+  background: var(--accent-subtle);
+  color: var(--accent);
+  border: 1px solid var(--accent-muted);
+  padding: 0.18rem 0.55rem;
+  border-radius: 3px;
+  font-family: var(--font-mono);
+  font-size: 0.62rem;
+  letter-spacing: 0.04em;
+  cursor: pointer;
+  transition: background var(--transition), border-color var(--transition);
+}
+
+.active-filter-chip:hover {
+  background: var(--accent-muted);
+  border-color: var(--accent);
+}
+
+.active-filter-chip-key {
+  color: var(--text-muted);
+  text-transform: uppercase;
+  font-size: 0.55rem;
+  letter-spacing: 0.1em;
+}
+
+.active-filter-chip-x {
+  color: var(--text-faint);
+  font-size: 0.85rem;
+  line-height: 0.6;
+  margin-left: 0.1rem;
+}
+
+.active-filter-chip:hover .active-filter-chip-x { color: var(--accent); }
+
+.store-result-count {
+  font-family: var(--font-mono);
+  font-size: 0.62rem;
+  color: var(--text-faint);
+  letter-spacing: 0.06em;
+  text-transform: uppercase;
+  white-space: nowrap;
+}
+
 /* === STORE GRID === */
 
 .store-grid {
   display: grid;
-  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
+  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
   gap: 0.65rem;
 }
 
@@ -532,6 +732,20 @@ h3 {
   color: var(--text-muted);
   border-radius: 3px;
   text-transform: lowercase;
+  cursor: pointer;
+  transition: color var(--transition), border-color var(--transition), background var(--transition);
+}
+
+.topic-tag:hover {
+  color: var(--accent);
+  border-color: var(--accent-muted);
+  background: var(--accent-subtle);
+}
+
+.topic-tag.active {
+  color: var(--accent);
+  border-color: var(--accent-muted);
+  background: var(--accent-subtle);
 }
 
 .store-card-footer {
@@ -559,6 +773,32 @@ h3 {
   color: var(--text-faint);
 }
 
+.store-card-stat-link {
+  background: none;
+  border: none;
+  padding: 0;
+  font-family: inherit;
+  font-size: inherit;
+  color: var(--text-faint);
+  cursor: pointer;
+  transition: color var(--transition);
+}
+
+.store-card-stat-link:hover { color: var(--accent); }
+
+.store-card-author-link {
+  background: none;
+  border: none;
+  padding: 0;
+  font-family: inherit;
+  font-size: inherit;
+  color: inherit;
+  cursor: pointer;
+  transition: color var(--transition);
+}
+
+.store-card-author-link:hover { color: var(--accent); }
+
 .store-card-actions {
   display: flex;
   gap: 0.3rem;
@@ -1517,6 +1757,14 @@ h3 {
   body { flex-direction: column; }
   .main { margin-left: 0; max-width: none; }
   .store-grid { grid-template-columns: 1fr; }
+  .store-layout { grid-template-columns: 1fr; gap: 1rem; }
+  .filter-rail {
+    position: static;
+    max-height: none;
+    overflow-y: visible;
+    padding-bottom: 0.85rem;
+    border-bottom: 1px solid var(--border);
+  }
   .project-header { grid-template-columns: 1fr; }
   .commit-meta { display: none; }
   .commit-row { grid-template-columns: 3.5rem 1fr; }
diff --git a/src/api.ts b/src/api.ts
index 94d5101..c86a5fb 100644
--- a/src/api.ts
+++ b/src/api.ts
@@ -2,7 +2,14 @@ import { readFileSync } from "node:fs";
 import { join } from "node:path";
 import { Hono } from "hono";
 import { fledge, fledgeJson, projectCwd } from "./fledge";
-import { browseAll, browsePlugins, browseTemplates, getRepoReadme } from "./github";
+import {
+  browseAll,
+  browsePlugins,
+  browseTemplates,
+  computeFacets,
+  getRepoReadme,
+  type BrowseFilters,
+} from "./github";
 import { gatherProjectInfo, openInBrowser } from "./project";
 import { parseConfigList } from "./config";
 
@@ -197,13 +204,31 @@ api.get("/info", async (c) => {
 
 api.get("/github/browse", async (c) => {
   const category = c.req.query("category") || "all";
-  const query = c.req.query("q") || undefined;
+  const filters: BrowseFilters = {
+    q: c.req.query("q") || undefined,
+    language: c.req.query("language") || undefined,
+    owner: c.req.query("owner") || undefined,
+    license: c.req.query("license") || undefined,
+    topics: c.req.queries("topic"),
+  };
   try {
     let repos;
-    if (category === "plugins") repos = await browsePlugins(query);
-    else if (category === "templates") repos = await browseTemplates(query);
-    else repos = await browseAll(query);
-    return c.json({ items: repos, total: repos.length });
+    if (category === "plugins") repos = await browsePlugins(filters);
+    else if (category === "templates") repos = await browseTemplates(filters);
+    else repos = await browseAll(filters);
+    return c.json({
+      items: repos,
+      total: repos.length,
+      facets: computeFacets(repos),
+      applied: {
+        category,
+        q: filters.q ?? null,
+        language: filters.language ?? null,
+        owner: filters.owner ?? null,
+        license: filters.license ?? null,
+        topics: filters.topics ?? [],
+      },
+    });
   } catch (e: unknown) {
     const msg = e instanceof Error ? e.message : String(e);
     return c.json({ error: msg, items: [] }, 502);
diff --git a/src/github.ts b/src/github.ts
index da77ede..6ae0e2a 100644
--- a/src/github.ts
+++ b/src/github.ts
@@ -58,6 +58,26 @@ interface SearchResult {
   items: GHRepo[];
 }
 
+export interface BrowseFilters {
+  q?: string;
+  language?: string;
+  topics?: string[];
+  owner?: string;
+  license?: string;
+}
+
+export interface FacetEntry {
+  value: string;
+  count: number;
+}
+
+export interface Facets {
+  topics: FacetEntry[];
+  languages: FacetEntry[];
+  owners: FacetEntry[];
+  licenses: FacetEntry[];
+}
+
 function toRepoList(result: SearchResult): GHRepo[] {
   return (result.items || []).map((r) => ({
     full_name: r.full_name,
@@ -73,28 +93,47 @@ function toRepoList(result: SearchResult): GHRepo[] {
   }));
 }
 
-export async function browsePlugins(query?: string): Promise<GHRepo[]> {
-  const q = query
-    ? `${query} topic:fledge-plugin`
-    : "topic:fledge-plugin";
-  const url = `${GITHUB_API}/search/repositories?q=${encodeURIComponent(q)}&sort=stars&order=desc&per_page=30`;
-  const result = (await ghFetch(url)) as SearchResult;
-  return toRepoList(result);
+// Topics that should not appear as user-selectable filters because they're
+// the markers that tell us a repo is a fledge plugin/template at all.
+const RESERVED_TOPICS = new Set(["fledge-plugin", "fledge-template", "fledge"]);
+
+export function buildQualifiers(baseTopic: string, filters: BrowseFilters): string {
+  const parts: string[] = [];
+  if (filters.q) parts.push(filters.q);
+  parts.push(`topic:${baseTopic}`);
+  for (const t of filters.topics || []) {
+    if (!t || RESERVED_TOPICS.has(t.toLowerCase())) continue;
+    parts.push(`topic:${t}`);
+  }
+  if (filters.language) parts.push(`language:${quoteIfNeeded(filters.language)}`);
+  if (filters.owner) parts.push(`user:${filters.owner}`);
+  if (filters.license) parts.push(`license:${filters.license}`);
+  return parts.join(" ");
+}
+
+function quoteIfNeeded(value: string): string {
+  return /\s/.test(value) ? `"${value}"` : value;
 }
 
-export async function browseTemplates(query?: string): Promise<GHRepo[]> {
-  const q = query
-    ? `${query} topic:fledge-template`
-    : "topic:fledge-template";
-  const url = `${GITHUB_API}/search/repositories?q=${encodeURIComponent(q)}&sort=stars&order=desc&per_page=30`;
+async function search(baseTopic: string, filters: BrowseFilters): Promise<GHRepo[]> {
+  const q = buildQualifiers(baseTopic, filters);
+  const url = `${GITHUB_API}/search/repositories?q=${encodeURIComponent(q)}&sort=stars&order=desc&per_page=50`;
   const result = (await ghFetch(url)) as SearchResult;
   return toRepoList(result);
 }
 
-export async function browseAll(query?: string): Promise<GHRepo[]> {
+export async function browsePlugins(filters: BrowseFilters = {}): Promise<GHRepo[]> {
+  return search("fledge-plugin", filters);
+}
+
+export async function browseTemplates(filters: BrowseFilters = {}): Promise<GHRepo[]> {
+  return search("fledge-template", filters);
+}
+
+export async function browseAll(filters: BrowseFilters = {}): Promise<GHRepo[]> {
   const [plugins, templates] = await Promise.all([
-    browsePlugins(query),
-    browseTemplates(query),
+    browsePlugins(filters),
+    browseTemplates(filters),
   ]);
   const seen = new Set<string>();
   const merged: GHRepo[] = [];
@@ -108,6 +147,52 @@ export async function browseAll(query?: string): Promise<GHRepo[]> {
   return merged;
 }
 
+function tally<Value>(
+  items: readonly GHRepo[],
+  pick: (repo: GHRepo) => readonly Value[],
+  key: (value: Value) => string,
+): FacetEntry[] {
+  const counts = new Map<string, { value: string; count: number }>();
+  for (const repo of items) {
+    const seen = new Set<string>();
+    for (const value of pick(repo)) {
+      const k = key(value);
+      if (!k || seen.has(k)) continue;
+      seen.add(k);
+      const entry = counts.get(k);
+      if (entry) entry.count += 1;
+      else counts.set(k, { value: String(value), count: 1 });
+    }
+  }
+  return [...counts.values()]
+    .sort((a, b) => b.count - a.count || a.value.localeCompare(b.value));
+}
+
+export function computeFacets(items: readonly GHRepo[]): Facets {
+  return {
+    topics: tally(
+      items,
+      (r) => (r.topics || []).filter((t) => !RESERVED_TOPICS.has(t.toLowerCase())),
+      (t) => t.toLowerCase(),
+    ),
+    languages: tally(
+      items,
+      (r) => (r.language ? [r.language] : []),
+      (l) => l,
+    ),
+    owners: tally(
+      items,
+      (r) => (r.owner?.login ? [r.owner.login] : []),
+      (l) => l.toLowerCase(),
+    ),
+    licenses: tally(
+      items,
+      (r) => (r.license?.spdx_id && r.license.spdx_id !== "NOASSERTION" ? [r.license.spdx_id] : []),
+      (l) => l,
+    ),
+  };
+}
+
 export async function getRepoReadme(owner: string, repo: string): Promise<string> {
   const url = `${GITHUB_API}/repos/${encodeURIComponent(owner)}/${encodeURIComponent(repo)}/readme`;
   const data = (await ghFetch(url)) as { content: string; encoding: string };
diff --git a/tests/github.test.ts b/tests/github.test.ts
new file mode 100644
index 0000000..608d71c
--- /dev/null
+++ b/tests/github.test.ts
@@ -0,0 +1,153 @@
+import { describe, expect, test } from "bun:test";
+import { buildQualifiers, computeFacets, type GHRepo } from "../src/github";
+
+function repo(overrides: Partial<GHRepo>): GHRepo {
+  return {
+    full_name: "acme/widget",
+    name: "widget",
+    description: null,
+    html_url: "https://github.com/acme/widget",
+    stargazers_count: 0,
+    language: null,
+    topics: [],
+    owner: { login: "acme", avatar_url: "" },
+    updated_at: "2025-01-01T00:00:00Z",
+    license: null,
+    ...overrides,
+  };
+}
+
+describe("buildQualifiers", () => {
+  test("always includes the base topic qualifier", () => {
+    expect(buildQualifiers("fledge-plugin", {})).toBe("topic:fledge-plugin");
+  });
+
+  test("prepends the free-text query before qualifiers", () => {
+    const q = buildQualifiers("fledge-plugin", { q: "deploy" });
+    expect(q).toBe("deploy topic:fledge-plugin");
+  });
+
+  test("adds extra topic, language, owner and license qualifiers", () => {
+    const q = buildQualifiers("fledge-template", {
+      topics: ["swift", "ios"],
+      language: "Swift",
+      owner: "CorvidLabs",
+      license: "mit",
+    });
+    expect(q).toBe(
+      "topic:fledge-template topic:swift topic:ios language:Swift user:CorvidLabs license:mit",
+    );
+  });
+
+  test("filters reserved topics so users can't override the base marker", () => {
+    const q = buildQualifiers("fledge-plugin", { topics: ["fledge-plugin", "fledge", "deploy"] });
+    expect(q).toBe("topic:fledge-plugin topic:deploy");
+  });
+
+  test("quotes language values that contain whitespace", () => {
+    const q = buildQualifiers("fledge-plugin", { language: "Objective C" });
+    expect(q).toBe('topic:fledge-plugin language:"Objective C"');
+  });
+
+  test("ignores empty/falsy filters", () => {
+    const q = buildQualifiers("fledge-plugin", {
+      q: "",
+      language: "",
+      owner: "",
+      license: "",
+      topics: ["", "swift"],
+    });
+    expect(q).toBe("topic:fledge-plugin topic:swift");
+  });
+});
+
+describe("computeFacets", () => {
+  const items: GHRepo[] = [
+    repo({
+      full_name: "corvidlabs/swift-ascii",
+      owner: { login: "CorvidLabs", avatar_url: "" },
+      language: "Swift",
+      topics: ["fledge-plugin", "swift", "ascii", "art"],
+      license: { spdx_id: "MIT" },
+    }),
+    repo({
+      full_name: "corvidlabs/swift-color",
+      owner: { login: "CorvidLabs", avatar_url: "" },
+      language: "Swift",
+      topics: ["fledge-plugin", "swift", "color"],
+      license: { spdx_id: "MIT" },
+    }),
+    repo({
+      full_name: "acme/py-helper",
+      owner: { login: "acme", avatar_url: "" },
+      language: "Python",
+      topics: ["fledge-template", "python"],
+      license: { spdx_id: "Apache-2.0" },
+    }),
+    repo({
+      full_name: "anon/no-license",
+      owner: { login: "anon", avatar_url: "" },
+      language: null,
+      topics: [],
+      license: { spdx_id: "NOASSERTION" },
+    }),
+  ];
+
+  test("excludes reserved topics", () => {
+    const facets = computeFacets(items);
+    const values = facets.topics.map((t) => t.value);
+    expect(values).not.toContain("fledge-plugin");
+    expect(values).not.toContain("fledge-template");
+  });
+
+  test("counts each topic once per repo and sorts by count desc", () => {
+    const facets = computeFacets(items);
+    expect(facets.topics).toEqual([
+      { value: "swift", count: 2 },
+      { value: "art", count: 1 },
+      { value: "ascii", count: 1 },
+      { value: "color", count: 1 },
+      { value: "python", count: 1 },
+    ]);
+  });
+
+  test("aggregates languages and owners correctly", () => {
+    const facets = computeFacets(items);
+    expect(facets.languages).toEqual([
+      { value: "Swift", count: 2 },
+      { value: "Python", count: 1 },
+    ]);
+    expect(facets.owners).toEqual([
+      { value: "CorvidLabs", count: 2 },
+      { value: "acme", count: 1 },
+      { value: "anon", count: 1 },
+    ]);
+  });
+
+  test("skips NOASSERTION licenses", () => {
+    const facets = computeFacets(items);
+    expect(facets.licenses).toEqual([
+      { value: "MIT", count: 2 },
+      { value: "Apache-2.0", count: 1 },
+    ]);
+  });
+
+  test("returns empty arrays for an empty input", () => {
+    const facets = computeFacets([]);
+    expect(facets).toEqual({ topics: [], languages: [], owners: [], licenses: [] });
+  });
+
+  test("dedupes duplicate topics within a single repo", () => {
+    const dup = [
+      repo({
+        full_name: "acme/dup",
+        topics: ["swift", "swift", "deploy"],
+      }),
+    ];
+    const facets = computeFacets(dup);
+    expect(facets.topics).toEqual([
+      { value: "deploy", count: 1 },
+      { value: "swift", count: 1 },
+    ]);
+  });
+});