Distinguish implicit harness fallback pins

Signed-off-by: kenny lopez <klopez4212@gmail.com>

desktop/src/features/agents/AGENTS.md

@@ -98,7 +98,11 @@ with a TypeScript lookup table or an id comparison in a component.
    without changing the persisted configuration used by existing agents.
    Legacy global defaults with no saved preferred runtime are treated as
    Buzz Agent-owned for this masking boundary, so hiding Buzz Agent cannot
-   leak its provider/model into another implicit fallback.
+   leak its provider/model into another implicit fallback. A persisted
+   per-instance harness override carries a durable explicit-vs-implicit marker:
+   explicit selections continue to inherit global provider/model defaults even
+   when the selected harness differs from the global preference, while
+   automatic runtime-less fallback pins keep mismatched defaults masked.
    Create-mode dialogs use the implicit masked config; existing definition and
    instance edit dialogs use the raw persisted config.
    `resolvePersonaRuntime` is the shared visibility boundary for every

desktop/src/features/agents/channelAgents.ts

@@ -66,6 +66,8 @@ export type CreateChannelManagedAgentInput = {
    * unpinned so the persona remains authoritative.
    */
   harnessOverride?: boolean;
+  /** The pin preserves an automatic runtime-less fallback, not an explicit pick. */
+  implicitHarnessFallback?: boolean;
   /** Preferred model ID from the persona. Passed to createManagedAgent. */
   model?: string;
   role?: Exclude<ChannelRole, "owner">;
@@ -355,6 +357,7 @@ export async function provisionChannelManagedAgent(
     acpCommand: "buzz-acp",
     agentCommand: input.runtime.command,
     harnessOverride: input.harnessOverride ?? false,
+    implicitHarnessFallback: input.implicitHarnessFallback ?? false,
     // Do NOT seed agentArgs from runtime.defaultArgs (see instanceInputForDefinition.ts
     // for the rationale — empty args let spawn resolve definition args live).
     agentArgs: [],

desktop/src/features/agents/lib/instanceInputForDefinition.test.mjs

@@ -84,12 +84,14 @@ test("row 2: harnessOverride follows the backend-aligned formula", async () => {
     gooseRuntime,
   );
   assert.equal(match.harnessOverride, true, "picked == configured → true");
+  assert.equal(match.implicitHarnessFallback, false);
 
   const noPreference = await buildInstanceInputForDefinition(
     persona({ runtime: undefined }),
     gooseRuntime,
   );
   assert.equal(noPreference.harnessOverride, true, "no preference → true");
+  assert.equal(noPreference.implicitHarnessFallback, true);
 
   const differs = await buildInstanceInputForDefinition(
     persona({ runtime: "claude" }),
@@ -100,6 +102,7 @@ test("row 2: harnessOverride follows the backend-aligned formula", async () => {
     false,
     "picked != configured → false (definition stays authoritative)",
   );
+  assert.equal(differs.implicitHarnessFallback, false);
 });
 
 test("provisioning pins a visible fallback for a runtime-less definition", () => {
@@ -111,6 +114,7 @@ test("provisioning pins a visible fallback for a runtime-less definition", () =>
   );
   assert.equal(resolved.runtime, gooseRuntime);
   assert.equal(resolved.harnessOverride, true);
+  assert.equal(resolved.implicitHarnessFallback, true);
 });
 
 test("provisioning uses product ordering and leaves unavailable configured fallbacks unpinned", () => {
@@ -121,12 +125,14 @@ test("provisioning uses product ordering and leaves unavailable configured fallb
   ]);
   assert.equal(ordered.runtime, buzzAgentRuntime);
   assert.equal(ordered.harnessOverride, true);
+  assert.equal(ordered.implicitHarnessFallback, true);
 
   const unavailable = resolveProvisioningRuntimeForDefinition("missing", [
     gooseRuntime,
   ]);
   assert.equal(unavailable.runtime, gooseRuntime);
   assert.equal(unavailable.harnessOverride, false);
+  assert.equal(unavailable.implicitHarnessFallback, false);
 });
 
 test("row 3: plain avatar URLs pass through; base64 data URIs upload via the injectable", async () => {
@@ -205,6 +211,7 @@ test("no backend intent is byte-identical to the pre-intent mapping", async () =
     agentArgs: [],
     mcpCommand: "goose-mcp",
     harnessOverride: true,
+    implicitHarnessFallback: false,
     model: undefined,
     provider: undefined,
     spawnAfterCreate: true,

desktop/src/features/agents/lib/instanceInputForDefinition.ts

@@ -120,7 +120,10 @@ export function resolveProvisioningRuntimeForDefinition(
   runtimes: readonly AcpRuntime[],
   preferredRuntimeId?: string | null,
   disabledRuntimeIds: readonly string[] = getDisabledAcpRuntimeIdsSnapshot(),
-): ResolvePersonaRuntimeResult & { harnessOverride: boolean } {
+): ResolvePersonaRuntimeResult & {
+  harnessOverride: boolean;
+  implicitHarnessFallback: boolean;
+} {
   const defaultRuntime = getDefaultPersonaRuntime(runtimes, preferredRuntimeId);
   const resolved = resolvePersonaRuntime(
     definitionRuntimeId,
@@ -137,6 +140,8 @@ export function resolveProvisioningRuntimeForDefinition(
         definitionRuntimeId,
         resolved.runtime.id,
       ),
+    implicitHarnessFallback:
+      resolved.runtime !== null && !definitionRuntimeId?.trim(),
   };
 }
 
@@ -207,6 +212,7 @@ export async function buildInstanceInputForDefinition(
       persona.runtime,
       runtime.id,
     ),
+    implicitHarnessFallback: !persona.runtime?.trim(),
     model: persona.model ?? undefined,
     provider: persona.provider ?? undefined,
     spawnAfterCreate: true,

desktop/src/features/agents/ui/AddTeamToChannelDialog.tsx

@@ -160,6 +160,7 @@ export function AddTeamToChannelDialog({
             persona.runtime,
             personaRuntime.id,
           ),
+          implicitHarnessFallback: !persona.runtime?.trim(),
           model: persona.model ?? undefined,
           personaId: persona.id,
           teamId: team.id,

desktop/src/features/channel-templates/useApplyTemplate.ts

@@ -93,6 +93,7 @@ export function useApplyTemplate() {
         name: persona.displayName,
         personaId: persona.id,
         harnessOverride: resolved.harnessOverride,
+        implicitHarnessFallback: resolved.implicitHarnessFallback,
         systemPrompt: persona.systemPrompt,
         avatarUrl: persona.avatarUrl ?? undefined,
         model: entry.model ?? persona.model ?? undefined,
@@ -121,6 +122,7 @@ export function useApplyTemplate() {
           name: persona.displayName,
           personaId: persona.id,
           harnessOverride: resolved.harnessOverride,
+          implicitHarnessFallback: resolved.implicitHarnessFallback,
           systemPrompt: persona.systemPrompt,
           avatarUrl: persona.avatarUrl ?? undefined,
           model: teamEntry.model ?? persona.model ?? undefined,

desktop/src/features/channels/ui/AddChannelBotDialog.tsx

@@ -156,6 +156,7 @@ export function AddChannelBotDialog({
           name: persona.displayName,
           personaId: persona.id,
           harnessOverride: resolved.harnessOverride,
+          implicitHarnessFallback: resolved.implicitHarnessFallback,
           systemPrompt: persona.systemPrompt,
           avatarUrl: persona.avatarUrl ?? undefined,
           model: persona.model ?? undefined,

desktop/src/features/channels/ui/useQuickBotDrop.ts

@@ -32,7 +32,7 @@ export function useQuickBotDrop(channelId: string | null) {
       setState({ pending: true, error: null });
 
       try {
-        const { harnessOverride, runtime } =
+        const { harnessOverride, implicitHarnessFallback, runtime } =
           resolveProvisioningRuntimeForDefinition(persona.runtime, providers);
 
         if (!runtime) {
@@ -51,6 +51,7 @@ export function useQuickBotDrop(channelId: string | null) {
           personaId: persona.id,
           model: persona.model ?? undefined,
           harnessOverride,
+          implicitHarnessFallback,
         });
 
         setState({ pending: false, error: null });

desktop/src/features/messages/ui/useMentionSendFlow.ts

@@ -326,7 +326,7 @@ export function useMentionSendFlow({
         }
         seenPersonaIds.add(persona.id);
 
-        const { harnessOverride, runtime } =
+        const { harnessOverride, implicitHarnessFallback, runtime } =
           resolveProvisioningRuntimeForDefinition(persona.runtime, runtimes);
         if (!runtime) {
           errors.push(`${displayName}: No agent runtime available.`);
@@ -342,6 +342,7 @@ export function useMentionSendFlow({
             name: persona.displayName,
             personaId: persona.id,
             harnessOverride,
+            implicitHarnessFallback,
             systemPrompt: persona.systemPrompt,
             avatarUrl: persona.avatarUrl ?? undefined,
             model: persona.model ?? undefined,

desktop/src/shared/api/tauri.ts

@@ -874,6 +874,7 @@ export async function createManagedAgent(input: CreateManagedAgentInput) {
         acpCommand: input.acpCommand,
         agentCommand: input.agentCommand,
         harnessOverride: input.harnessOverride ?? false,
+        implicitHarnessFallback: input.implicitHarnessFallback ?? false,
         agentArgs: input.agentArgs,
         mcpCommand: input.mcpCommand,
         turnTimeoutSeconds: input.turnTimeoutSeconds,

desktop/src/shared/api/types.ts

@@ -456,6 +456,11 @@ export type CreateManagedAgentInput = {
    * same persona runtime id, while still ignoring missing-runtime fallbacks.
    */
   harnessOverride?: boolean;
+  /**
+   * True when `harnessOverride` pins an automatically selected runtime for a
+   * runtime-less persona rather than a runtime the user explicitly selected.
+   */
+  implicitHarnessFallback?: boolean;
   agentArgs?: string[];
   mcpCommand?: string;
   turnTimeoutSeconds?: number;