fix(mods): don't prompt to install dependencies that are already installed

The 'install dependencies' dialog listed every dependency the selected
Modrinth version declared, with no check against what's already in the
mods folder — so reinstalling/updating a mod with common deps (Fabric
API, Cloth Config, etc.) nagged you to 'install' something already
there, matched only against the exact same version's own hash, not
any installed version of the dependency itself.

Added getInstalledModrinthProjectIds(): bulk-hashes every jar in the
mods folder and resolves them against Modrinth's version_files
endpoint in one request to get each installed jar's project id.
handleInstallation() now filters the dependency list against that set
before prompting — already-installed deps are silently dropped, and if
that empties the list entirely, the dialog is skipped altogether and
the mod downloads directly, same as the no-dependencies case.

(CurseForge-sourced mods don't populate versionDependencyIds at all
today, so this only affects the Modrinth dependency-resolution path —
consistent with the existing 'no deps' short-circuit already only
applying there.)

Author: MaxJubayerYT

app_pojavlauncher/src/main/java/net/kdt/pojavlaunch/fragments/ModsSearchFragment.java

@@ -450,6 +450,36 @@ public void handleInstallation(Context context, ModDetail modDetail, int selecte
                 return;
             }
 
+            // Drop any dependency that's already sitting in the mods folder (as any
+            // version, not just the one this mod happens to ask for) — otherwise every
+            // reinstall/update of a mod with common dependencies (Fabric API, Cloth
+            // Config, etc.) nags you to "install" something you already have.
+            PojavApplication.sExecutorService.execute(() -> {
+                java.util.Set<String> installedProjectIds = getInstalledModrinthProjectIds();
+                List<String> remainingIds = new ArrayList<>();
+                List<String> remainingTypes = new ArrayList<>();
+                for (int i = 0; i < depIds.length; i++) {
+                    if (depIds[i] != null && installedProjectIds.contains(depIds[i])) continue;
+                    remainingIds.add(depIds[i]);
+                    remainingTypes.add((depTypes != null && i < depTypes.length) ? depTypes[i] : "required");
+                }
+
+                if (remainingIds.isEmpty()) {
+                    // Every dependency is already installed — no need to prompt at all
+                    mMainHandler.post(() ->
+                            downloadMod(context, url, fileName, new String[0], new String[0], oldFilePath));
+                    return;
+                }
+
+                mMainHandler.post(() -> promptForDependencies(context, url, fileName,
+                        remainingIds.toArray(new String[0]), remainingTypes.toArray(new String[0]), oldFilePath));
+            });
+        }
+
+        /** Fetches display names for the (already filtered to not-yet-installed) dependency
+         *  list, then shows the install dialog once every name has resolved. */
+        private void promptForDependencies(Context context, String url, String fileName,
+                                            String[] depIds, String[] depTypes, String oldFilePath) {
             // Fetch project names for all deps, then show dialog
             String[] labels = new String[depIds.length];
             final boolean[] checkedDefaults = new boolean[depIds.length];
@@ -572,6 +602,55 @@ private void downloadDependency(String projectId, File modsDir) {
             }
         }
 
+        /**
+         * Hashes every jar currently in the mods folder and bulk-resolves them against
+         * Modrinth's version_files endpoint to find which Modrinth project each one
+         * belongs to — used to filter "install dependencies" prompts down to ones that
+         * aren't already installed under some other version/file name.
+         */
+        private java.util.Set<String> getInstalledModrinthProjectIds() {
+            java.util.Set<String> projectIds = new java.util.HashSet<>();
+            File modsDir = getModsDir();
+            File[] files = modsDir.listFiles(f -> f.isFile() &&
+                    (f.getName().endsWith(".jar") || f.getName().endsWith(".jar.disabled")));
+            if (files == null || files.length == 0) return projectIds;
+
+            List<String> hashes = new ArrayList<>();
+            for (File f : files) {
+                String hash = sha1Hex(f);
+                if (hash != null) hashes.add(hash);
+            }
+            if (hashes.isEmpty()) return projectIds;
+
+            try {
+                com.google.gson.JsonObject body = new com.google.gson.JsonObject();
+                com.google.gson.JsonArray hashArray = new com.google.gson.JsonArray();
+                for (String hash : hashes) hashArray.add(hash);
+                body.add("hashes", hashArray);
+                body.addProperty("algorithm", "sha1");
+
+                java.util.Map<String, String> headers = new java.util.HashMap<>();
+                headers.put("Content-Type", "application/json");
+                headers.put("Accept", "application/json");
+
+                String responseRaw = net.kdt.pojavlaunch.modloaders.modpacks.api.ApiHandler.postRaw(
+                        headers, "https://api.modrinth.com/v2/version_files", body.toString());
+                if (responseRaw == null) return projectIds;
+
+                com.google.gson.JsonObject response = com.google.gson.JsonParser.parseString(responseRaw).getAsJsonObject();
+                for (java.util.Map.Entry<String, com.google.gson.JsonElement> entry : response.entrySet()) {
+                    if (!entry.getValue().isJsonObject()) continue;
+                    com.google.gson.JsonObject version = entry.getValue().getAsJsonObject();
+                    if (version.has("project_id") && !version.get("project_id").isJsonNull()) {
+                        projectIds.add(version.get("project_id").getAsString());
+                    }
+                }
+            } catch (Exception e) {
+                Log.w(TAG, "Failed to bulk-resolve installed mod hashes: " + e.getMessage());
+            }
+            return projectIds;
+        }
+
         private String fetchProjectName(String projectId) {
             try {
                 net.kdt.pojavlaunch.modloaders.modpacks.api.ApiHandler handler =