common: resolve draft repo to its requested sidecar (#25955)

With -hfd pointing to a repo shipping speculative sidecars, the draft
resolved to the main model of that repo, since find_best_model()
excludes sidecar files, and the explicit draft plan suppressed the
sidecar discovery on the -hf repo.

The draft plan already discovers its sidecars, they were just never
consumed. Wire them as the draft, following the fallback pattern of
the main plan, so this now works as expected:

llama-server -hf repo -hfd repo --spec-type draft-dflash

diff --git a/common/arg.cpp b/common/arg.cpp
index 8a74e5f2b1f9f0387aac97bd37684d85566ec0ff..48e274774231531936257fabfbb1262916436f65 100644 (file)
--- a/common/arg.cpp
+++ b/common/arg.cpp
@@ -527,8 +527,43 @@ void common_models_handler_apply(common_models_handler & handler, common_params
         }
     };
 
+    // when a sidecar type is requested, the draft repo resolves to its sidecar instead of a full model
+    const bool spec_sidecar_found = !plan_spec.mtp.local_path.empty() ||
+                                    !plan_spec.dflash.local_path.empty() ||
+                                    !plan_spec.eagle3.local_path.empty();
+    if (!plan_spec.mtp.local_path.empty() && !had_spec_url) {
+        tasks.emplace_back(plan_spec.mtp, opts, [&]() {
+            // only use the discovered MTP head when no draft path is set yet
+            if (params.speculative.draft.mparams.path.empty()) {
+                params.speculative.draft.mparams.path = hf_cache::finalize_file(plan_spec.mtp);
+            } else {
+                hf_cache::finalize_file(plan_spec.mtp);
+            }
+        });
+    }
+    if (!plan_spec.dflash.local_path.empty() && !had_spec_url) {
+        tasks.emplace_back(plan_spec.dflash, opts, [&]() {
+            // only use the discovered DFlash sidecar when no draft path is set yet
+            if (params.speculative.draft.mparams.path.empty()) {
+                params.speculative.draft.mparams.path = hf_cache::finalize_file(plan_spec.dflash);
+            } else {
+                hf_cache::finalize_file(plan_spec.dflash);
+            }
+        });
+    }
+    if (!plan_spec.eagle3.local_path.empty() && !had_spec_url) {
+        tasks.emplace_back(plan_spec.eagle3, opts, [&]() {
+            // only use the discovered Eagle3 sidecar when no draft path is set yet
+            if (params.speculative.draft.mparams.path.empty()) {
+                params.speculative.draft.mparams.path = hf_cache::finalize_file(plan_spec.eagle3);
+            } else {
+                hf_cache::finalize_file(plan_spec.eagle3);
+            }
+        });
+    }
+
     // handle plan_spec (e.g. --spec-draft-hf)
-    if (!plan_spec.model_files.empty() && !had_spec_url) {
+    if (!plan_spec.model_files.empty() && !had_spec_url && !spec_sidecar_found) {
         add_tasks(plan_spec.model_files, plan_spec.primary, params.speculative.draft.mparams);
         had_spec_url = true;
     }