From ae433124b3f88690924d56c29913779ffbdee11c Mon Sep 17 00:00:00 2001
From: Aleksander Grygier <aleksander.grygier@gmail.com>
Date: Fri, 2 Oct 2026 00:16:33 +0200
Subject: [PATCH] ui : make resuming a paused download work

Re-posting the tag of a paused download hit the router's "already
exists" check, because a paused download parks its entry as DOWNLOADED
until the next reload: a download entry that is not running is now
replaced and resumed. The UI keeps the paused row when the request still
fails, instead of dropping it and looking finished.

Assisted-by: pi
---
 tools/server/server-models.cpp                 | 18 ++++++++++++++++--
 .../ui/src/lib/stores/models/status.svelte.ts  | 11 ++++++++++-
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/tools/server/server-models.cpp b/tools/server/server-models.cpp
index a8996b00c9..7f3151b180 100644
--- a/tools/server/server-models.cpp
+++ b/tools/server/server-models.cpp
@@ -2158,9 +2158,23 @@ void server_models_routes::init_routes() {
             throw std::invalid_argument("model validation failed, unable to download");
         }
 
-        // reject if model already exists
+        // reject if model already exists, but a paused download parks its entry as
+        // DOWNLOADED until the next reload: re-posting that tag is how a resume is
+        // asked for, so a download that is not running is replaced instead
         if (models.has_model(name)) {
-            throw std::invalid_argument("model '" + name + "' already exists");
+            auto existing = models.get_meta(name);
+
+            // the entry can disappear here: get_meta() triggers the reload that
+            // erases a finished download, which is the resume case as well
+            const bool resumable = existing.has_value() && !existing->is_running() &&
+                (existing->status == SERVER_MODEL_STATUS_DOWNLOADED ||
+                 existing->status == SERVER_MODEL_STATUS_DOWNLOADING);
+
+            if (existing.has_value() && !resumable) {
+                throw std::invalid_argument("model '" + name + "' already exists");
+            }
+
+            SRV_INF("resuming download for model '%s'\n", name.c_str());
         }
 
         // then, proceed with the actual download
diff --git a/tools/ui/src/lib/stores/models/status.svelte.ts b/tools/ui/src/lib/stores/models/status.svelte.ts
index 642e8707a3..9790ac35b9 100644
--- a/tools/ui/src/lib/stores/models/status.svelte.ts
+++ b/tools/ui/src/lib/stores/models/status.svelte.ts
@@ -254,6 +254,7 @@ export class ModelStatusManager {
 		// not fall back to 0%, and let the server discard its stale DOWNLOADED entry
 		// (via the list fetch) before re-posting
 		const snapshot = this.pausedDownloads.get(repoWithTag) ?? null;
+		const wasPaused = this.pausedDownloads.has(repoWithTag);
 
 		if (this.deletePausedDownload(repoWithTag) || this.stopRequests.delete(repoWithTag)) {
 			await this.host.fetchRouterModels();
@@ -271,7 +272,15 @@ export class ModelStatusManager {
 
 			toast.success(`Download started: ${this.host.toDisplayName(repoWithTag)}`);
 		} catch (error) {
-			toast.error(`Download failed: ${repoWithTag}`);
+			// the download did not start: a resumed one stays paused rather than
+			// dropping off the list, which reads as a finished download
+			if (wasPaused) {
+				this.setPausedDownload(repoWithTag, snapshot);
+			}
+
+			const reason = error instanceof Error ? error.message : 'unknown error';
+
+			toast.error(`Download failed: ${repoWithTag} (${reason})`);
 
 			throw error;
 		}