Merge pull request #14152 from lancy69/fix/14126-minimal-image-capability

fix(composition): allow lightweight mode without image capability

desktop/frontend-next/src/port/composition.ts

@@ -1,7 +1,7 @@
 import definitions from "../../../../internal/contract/agentcomposition/builtins.json";
 
 export type CompositionKind = "tools" | "skills" | "mcp" | "extensions" | "hooks" | "commands";
-export interface CompositionModule { id: string; parameters?: Record<string, unknown> }
+export interface CompositionModule { id: string; parameters?: Record<string, unknown>; optional?: boolean }
 // A module the editor offers: the id is what a preset stores; the description is what the module
 // says about itself, for the person choosing, and is never saved.
 export interface CompositionChoice { id: string; description?: string; source?: "builtin" | "custom" }

desktop/frontend-next/src/port/mock_composition.test.ts

@@ -50,3 +50,32 @@ describe("project composition authority", () => {
     await expect(presets.selectAgentComposition("user:gone")).rejects.toMatchObject({reason:{code:"agent_composition.unavailable",params:{module:"tools:no_such_tool"}}});
   });
 });
+
+describe("optional tool dependencies", () => {
+  it("admits missing optional tools without relaxing required tool selection", async () => {
+    const presets = new MockCompositions();
+    const definition = {...builtinCompositions()[0],id:"user:optional",tools:{mode:"select" as const,members:[{id:"bash"},{id:"missing_image",optional:true}]}};
+    const saved = await presets.saveAgentPreset(definition,"");
+    await expect(presets.selectAgentComposition(definition.id)).resolves.toMatchObject({id:definition.id});
+    await presets.saveAgentPreset({...definition,tools:{...definition.tools,members:[...definition.tools.members,{id:"missing_required"}]}},saved.revision);
+    await expect(presets.selectAgentComposition(definition.id)).rejects.toMatchObject({reason:{code:"agent_composition.unavailable",params:{module:"tools:missing_required"}}});
+  });
+
+  it.each([undefined, false, true])("reports missing imported tools unless optional is true (%s)", async (optional) => {
+    const presets = new MockCompositions();
+    const definition = {...builtinCompositions()[0],id:"user:import",tools:{mode:"select" as const,members:[{id:"missing_image",optional}]}};
+    const preview = await presets.importAgentPreset(definition);
+    if (optional) expect(preview.diagnostics).toEqual([]);
+    else {
+      expect(preview.diagnostics).toHaveLength(1);
+      expect(preview.diagnostics[0]).toMatchObject({code:"agent_composition.unavailable",module:"tools:missing_image"});
+    }
+  });
+
+  it.each(["skills","mcp","extensions","hooks","commands"] as const)("rejects optional %s members on save and import", async (kind) => {
+    const presets = new MockCompositions();
+    const definition = {...builtinCompositions()[0],id:"user:import",[kind]:{mode:"select" as const,members:[{id:"missing_dependency",optional:true}]}};
+    await expect(presets.saveAgentPreset(definition,"")).rejects.toMatchObject({reason:{code:"agent_composition.invalid"}});
+    await expect(presets.importAgentPreset(definition)).rejects.toMatchObject({reason:{code:"agent_composition.invalid"}});
+  });
+});

desktop/frontend-next/src/port/mock_composition.ts

@@ -38,12 +38,15 @@ export class MockCompositions {
   private fail(status:number,code:string):never { throw new HttpError(status,"",{code:`agent_composition.${code}`}); }
   private requireModules(definition:AgentComposition) {
     for (const kind of ["tools"] as const) for (const member of definition[kind]?.members ?? []) {
-      if (definition[kind]?.mode==="select" && !(MOCK_MODULES?.[kind] ?? []).some((m)=>m.id===member.id)) {
+      if (definition[kind]?.mode==="select" && !member.optional && !(MOCK_MODULES?.[kind] ?? []).some((m)=>m.id===member.id)) {
         throw new HttpError(409,"",{code:"agent_composition.unavailable",params:{module:`${kind}:${member.id}`,detail:"Required module is unavailable or was revoked."}});
       }
     }
   }
-  private validateAuthority(definition:AgentComposition) {
+  private validateDefinition(definition:AgentComposition) {
+    for (const kind of ["skills","mcp","extensions","hooks","commands"] as const) {
+      if (definition[kind]?.members.some((member)=>member.optional)) this.fail(400,"invalid");
+    }
     if (!definition.id.startsWith("project:")) return;
     for (const kind of ["mcp","extensions"] as const) for (const member of definition[kind]?.members ?? []) {
       if (Object.entries(member.parameters ?? {}).some(([key,value])=>["args","url","env","headers"].includes(key.toLowerCase()) && value!=null)) this.fail(400,"invalid");
@@ -55,7 +58,7 @@ export class MockCompositions {
     const prior=this.catalog.presets.find((v)=>v.definition.id===definition.id);
     if ((prior?.revision ?? "")!==expectedRevision) this.fail(409,"conflict");
     if (!/^(user|project):[a-zA-Z0-9][a-zA-Z0-9._-]{0,63}$/.test(definition.id) || !definition.name.trim()) this.fail(400,"invalid");
-    this.validateAuthority(definition);
+    this.validateDefinition(definition);
     const version={definition:structuredClone(definition),revision:`mock-${++this.library.revision}`};
     const items=definition.id.startsWith("project:") ? this.library.projects.get(this.workspace) ?? [] : this.library.user;
     const next=[...items.filter((v)=>v.definition.id!==definition.id),version];
@@ -81,10 +84,10 @@ export class MockCompositions {
   }
   async importAgentPreset(content:AgentComposition) {
     if (content.schemaVersion!==1 || !content.name || !content.persona) this.fail(400,"invalid");
-    this.validateAuthority(content);
+    this.validateDefinition(content);
     const diagnostics:AgentPresetCatalog["diagnostics"]=[];
     for (const kind of ["tools","skills","mcp","extensions","hooks","commands"] as const) for (const member of content[kind]?.members ?? []) {
-      if (!(MOCK_MODULES?.[kind] ?? []).some((m)=>m.id===member.id)) diagnostics.push({code:"agent_composition.unavailable",module:`${kind}:${member.id}`,detail:"Dependency is not available on this host."});
+      if (!(kind==="tools" && member.optional) && !(MOCK_MODULES?.[kind] ?? []).some((m)=>m.id===member.id)) diagnostics.push({code:"agent_composition.unavailable",module:`${kind}:${member.id}`,detail:"Dependency is not available on this host."});
     }
     return {definition:structuredClone(content),diagnostics};
   }

docs/AGENT_COMPOSITIONS.md

@@ -74,10 +74,10 @@ editable rows. Usage, details and copy do not change the new-task default.
 | Mode | Behavior |
 | --- | --- |
 | Everyday partner (`builtin:general`) | Inherit current configuration for everyday code, file and research work. The stable ID preserves existing defaults. |
-| Lightweight partner (`builtin:minimal`) | A concise system persona, terminal (`bash`) and image reading (`view_image`), with native context compaction. Requires a vision-capable model. |
+| Lightweight partner (`builtin:minimal`) | A concise system persona and terminal (`bash`), with native context compaction. Adds image reading (`view_image`) when the selected model reads images and the tool is enabled. |
 
-These display names replace Standard and Minimal; their IDs and capabilities
-stay unchanged. Retained conversations keep their saved names and revisions.
+The stable IDs preserve existing defaults. Retained conversations keep their
+saved names, revisions and module requirements.
 
 The persona reference is DeepSeek Harness commit
 `687f282e8625c6b8d11ff58211a90524be2e4317`:
@@ -99,8 +99,9 @@ It retains the host controls needed to answer and ask questions. Its terminal
 can still modify files and access the network under existing permissions and
 sandbox rules; Lightweight partner is not a read-only mode.
 
-Missing image capability or
-disabled tools produce an explicit dependency error rather than another tool set.
+Missing required tools produce an explicit dependency error. Lightweight partner
+requires `bash`; its `view_image` member is optional, so a text-only model or a
+configuration that disables image reading can still use the terminal.
 
 Code review and Research are no longer built-in catalog entries. Their existing
 conversations retain the original binding. An old default pointing to a retired
@@ -110,6 +111,13 @@ Copy a built-in to customize it. Each module group either follows current author
 configuration, including resources enabled later, or uses only the selected IDs. An empty explicit
 selection disables the group.
 
+A selected tool member may declare `"optional": true`, for example
+`{"id":"view_image","optional":true}`. It is admitted only if already available;
+the declaration does not enable a disabled tool or grant image capability.
+
+Omitting `optional` keeps the member required. Other module groups do not accept
+optional members.
+
 The editor lists locally available modules;
 imports preview missing dependencies without installing or launching them.
 

docs/AGENT_COMPOSITIONS.zh.md

@@ -51,10 +51,9 @@ Studio 的「Agent 预设」把人设、工具、技能、MCP、扩展、Hook
 | 模式 | 行为 |
 | --- | --- |
 | 日常搭档（`builtin:general`） | 创建会话时继承当前配置，处理日常代码、文件与资料任务；保留原稳定标识以兼容默认选择。 |
-| 轻装搭档（`builtin:minimal`） | 使用简短人设、终端（`bash`）和图片读取（`view_image`），保留原生上下文压缩，需要支持读图的模型。 |
+| 轻装搭档（`builtin:minimal`） | 使用简短人设和终端（`bash`），保留原生上下文压缩。所选模型支持读图且工具已启用时，额外提供图片读取（`view_image`）。 |
 
-「日常搭档」「轻装搭档」分别替代原显示名称「标准模式」「精简模式」，ID 和能力
-保持不变。已有会话继续保留保存时的名称和版本。
+内置项的稳定 ID 继续兼容已有默认选择。已有会话保留保存时的名称、版本和模块要求。
 
 人设提示参考 DeepSeek Harness 的提交 `687f282e8625c6b8d11ff58211a90524be2e4317`：
 [standard][harness-standard] 使用简短的编程 Agent 身份提示；
@@ -70,7 +69,8 @@ Reasonix 已使用相同的 minimal 开场提示。
 
 轻装搭档不装载自定义技能、命令、MCP、扩展、Hook 或子 Agent，保留回答和提问
 所需的宿主控制工具。终端仍能修改文件和访问网络，继续遵守已有权限与沙箱；
-轻装搭档不是只读模式。图片能力不可用或所选工具被禁用时会明确报告依赖错误。
+轻装搭档不是只读模式。`bash` 是必需工具，缺失时会报告依赖错误；`view_image`
+是可选工具，模型未启用读图能力或配置禁用该工具时，仍可使用终端。
 
 代码审查、资料研究不再作为内置目录项提供；已有会话继续保留原绑定版本。
 如果旧默认指向已移除的内置项，目录会提示用户明确选择新的默认项，不自动替换。
@@ -79,6 +79,11 @@ Reasonix 已使用相同的 minimal 开场提示。
 「仅使用所选项」；显式空列表表示禁用。编辑器提供本机模块目录，导入先预览
 缺失依赖，不会安装依赖或启动程序。
 
+所选工具成员可声明 `"optional": true`，例如
+`{"id":"view_image","optional":true}`。只有当前已可用的工具才会加入，不会因此
+启用已禁用的工具或授予模型读图能力。不填写 `optional` 时仍为必需工具；
+其他模块类型不接受可选成员。
+
 设置导航显示为「人设」。编辑页直接展示名称、用途、两段人设文本和可选运行时
 上下文开关；工具、技能与扩展按需展开。存放范围与自动生成的 ID 也直接展示，
 保存后 ID 与范围不可修改。

internal/assembly/boot/composition.go

@@ -184,6 +184,9 @@ func verifySelected[T any](kind string, s agentcomposition.Selection, items []T,
 		return nil
 	}
 	for _, m := range s.Members {
+		if kind == "tools" && m.Optional {
+			continue
+		}
 		if !slices.ContainsFunc(items, func(v T) bool { return id(v) == m.ID }) {
 			return agentcomposition.Unavailable(kind+":"+m.ID, "Required module is unavailable or was revoked.")
 		}

internal/assembly/boot/effect_view_image_test.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"net/http"
 	"net/http/httptest"
+	"slices"
 	"strings"
 	"testing"
 	"time"
@@ -24,12 +25,16 @@ func TestEffectViewImageReachesOnlyAModelThatReadsImages(t *testing.T) {
 	for _, tc := range []struct {
 		vision      bool
 		composition string
+		enabled     string
+		missing     string
 	}{
-		{true, ""}, {false, ""},
-		{true, "builtin:general"}, {false, "builtin:general"},
-		{true, "builtin:minimal"}, {false, "builtin:minimal"},
+		{true, "", "", ""}, {false, "", "", ""},
+		{true, "builtin:general", "", ""}, {false, "builtin:general", "", ""},
+		{true, "builtin:minimal", "", ""}, {false, "builtin:minimal", "", ""},
+		{true, "builtin:minimal", `["bash"]`, ""}, {false, "builtin:minimal", `["bash"]`, ""},
+		{true, "builtin:minimal", `["view_image"]`, "tools:bash"},
 	} {
-		t.Run(fmt.Sprintf("vision=%v/composition=%s", tc.vision, tc.composition), func(t *testing.T) {
+		t.Run(fmt.Sprintf("vision=%v/composition=%s/enabled=%s", tc.vision, tc.composition, tc.enabled), func(t *testing.T) {
 			t.Parallel()
 			home := statedBootHome(t)
 			search := httptest.NewServer(http.HandlerFunc(func(http.ResponseWriter, *http.Request) {
@@ -37,6 +42,9 @@ func TestEffectViewImageReachesOnlyAModelThatReadsImages(t *testing.T) {
 			}))
 			t.Cleanup(search.Close)
 			writeFile(t, home, "config.toml", fmt.Sprintf("[tools]\nweb_search_backends = [\"searxng\"]\nsearxng_url = %q\n", search.URL))
+			if tc.enabled != "" {
+				writeFile(t, home, "config.toml", fmt.Sprintf("[tools]\nenabled = %s\nweb_search_backends = [\"searxng\"]\nsearxng_url = %q\n", tc.enabled, search.URL))
+			}
 			dir := testenv.TempDir(t)
 			rec := &peerToolProvider{}
 			kind := fmt.Sprintf("boot-view-image-%s", strings.ReplaceAll(t.Name(), "/", "-"))
@@ -55,9 +63,10 @@ vision = %v
 `, kind, tc.vision))
 			approveWorkspaceAt(t, home, dir)
 			ctrl, err := Build(context.Background(), Options{Home: home, WorkspaceRoot: dir, Sink: event.Discard, AgentComposition: tc.composition})
-			if tc.composition == "builtin:minimal" && !tc.vision {
-				if !errors.Is(err, agentcomposition.ErrUnavailable) {
-					t.Fatalf("text-only model must report unavailable image capability: %v", err)
+			if tc.missing != "" {
+				var diagnostic *agentcomposition.DiagnosticError
+				if !errors.As(err, &diagnostic) || len(diagnostic.Diagnostics) != 1 || diagnostic.Diagnostics[0].Module != tc.missing {
+					t.Fatalf("error = %v, want missing required module %s", err, tc.missing)
 				}
 				return
 			}
@@ -68,11 +77,14 @@ vision = %v
 			ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
 			defer cancel()
 			_ = ctrl.Run(ctx, "hi")
+			if !slices.Contains(rec.toolNames(), "bash") {
+				t.Fatalf("required bash tool missing from provider request: %v", rec.toolNames())
+			}
 			has := false
 			for _, name := range rec.toolNames() {
 				has = has || name == "view_image"
 			}
-			want := tc.vision
+			want := tc.vision && tc.enabled == ""
 			if has != want {
 				t.Fatalf("vision=%v composition=%s: tools in the first request = %v", tc.vision, tc.composition, rec.toolNames())
 			}

internal/contract/agentcomposition/builtin-revisions.json

@@ -1,4 +1,4 @@
 {
   "builtin:general": "90d6a645648f1767371fedc2c01a487428dc847417c77bddd82a365520a65dfb",
-  "builtin:minimal": "b8893eec828a9596efe7d1d12264d3124f0041f77d5d29520eecacd1d6d06cdf"
+  "builtin:minimal": "b25962a98543abdb021332dcb2216d66a59ad90a3395c3d2f7d9cc30186a7a5b"
 }

internal/contract/agentcomposition/builtins.json

@@ -9,7 +9,7 @@
   {
     "schemaVersion": 1, "id": "builtin:minimal", "name": "轻装搭档", "description": "带上终端和看图工具，轻装开工。和你一起处理小任务、快速试验，也方便对比模型表现。",
     "persona": {"prefix": "You are a helpful software engineer assistant.", "suffix": "", "include_runtime_context": false},
-    "tools": {"mode":"select","members":[{"id":"bash"},{"id":"view_image"}]},
+    "tools": {"mode":"select","members":[{"id":"bash"},{"id":"view_image","optional":true}]},
     "skills": {"mode":"select","members":[]}, "mcp": {"mode":"select","members":[]},
     "extensions": {"mode":"select","members":[]}, "hooks": {"mode":"select","members":[]}, "commands": {"mode":"select","members":[]}
   }

internal/contract/agentcomposition/composition.go

@@ -32,6 +32,7 @@ type Persona struct {
 type Module struct {
 	ID         string          `json:"id"`
 	Parameters json.RawMessage `json:"parameters,omitempty"`
+	Optional   bool            `json:"optional,omitempty"`
 }
 
 type Selection struct {
@@ -140,7 +141,7 @@ func (d Definition) Validate() error {
 	if len(d.Persona.Prefix) > 32768 || len(d.Persona.Suffix) > 32768 {
 		return fmt.Errorf("%w: persona", ErrInvalid)
 	}
-	for _, s := range []Selection{d.Tools, d.Skills, d.MCP, d.Extensions, d.Hooks, d.Commands} {
+	for group, s := range []Selection{d.Tools, d.Skills, d.MCP, d.Extensions, d.Hooks, d.Commands} {
 		if len(s.Members) > 10000 {
 			return ErrInvalid
 		}
@@ -149,6 +150,9 @@ func (d Definition) Validate() error {
 		}
 		seen := map[string]bool{}
 		for _, m := range s.Members {
+			if m.Optional && group != 0 {
+				return fmt.Errorf("%w: optional is only supported for tools", ErrInvalid)
+			}
 			if m.ID == "" || len(m.ID) > 1024 || seen[m.ID] {
 				return fmt.Errorf("%w: duplicate or empty module %q", ErrInvalid, m.ID)
 			}

internal/contract/agentcomposition/composition_test.go

@@ -1,6 +1,7 @@
 package agentcomposition
 
 import (
+	"encoding/json"
 	"errors"
 	"testing"
 )
@@ -46,8 +47,116 @@ func TestMinimalTemplateHasNoAutomationOrDelegation(t *testing.T) {
 				t.Fatalf("%s inherits modules", d.ID)
 			}
 		}
-		if d.Tools.Mode != Select || len(d.Tools.Members) != 2 || d.Tools.Members[0].ID != "bash" || d.Tools.Members[1].ID != "view_image" {
+		if d.Tools.Mode != Select || len(d.Tools.Members) != 2 || d.Tools.Members[0].ID != "bash" || d.Tools.Members[0].Optional || d.Tools.Members[1].ID != "view_image" || !d.Tools.Members[1].Optional {
 			t.Fatalf("minimal tools = %+v", d.Tools)
 		}
 	}
 }
+
+func TestOptionalModulesDecodeAndValidate(t *testing.T) {
+	for _, group := range []string{"tools", "skills", "mcp", "extensions", "hooks", "commands"} {
+		t.Run(group, func(t *testing.T) {
+			d := Builtins()[0]
+			data, err := json.Marshal(d)
+			if err != nil {
+				t.Fatal(err)
+			}
+			var document map[string]json.RawMessage
+			if err := json.Unmarshal(data, &document); err != nil {
+				t.Fatal(err)
+			}
+			document[group] = json.RawMessage(`{"mode":"select","members":[{"id":"example","optional":true}]}`)
+			data, err = json.Marshal(document)
+			if err != nil {
+				t.Fatal(err)
+			}
+			decoded, err := Decode(data)
+			if group != "tools" {
+				if !errors.Is(err, ErrInvalid) {
+					t.Fatalf("optional %s decode error = %v", group, err)
+				}
+				if !errors.Is(decoded.Validate(), ErrInvalid) {
+					t.Fatalf("optional %s passed structural validation", group)
+				}
+				return
+			}
+			if err != nil {
+				t.Fatal(err)
+			}
+			if !decoded.Tools.Members[0].Optional {
+				t.Fatal("optional tool lost during decode")
+			}
+		})
+	}
+}
+
+func TestOptionalToolsBindingRoundTrip(t *testing.T) {
+	d := Builtins()[1]
+	binding := Binding{
+		Resolved: d,
+		Version:  Version{Definition: d, Revision: Revision(d)},
+	}
+	binding.Seal()
+	restored := Clone(binding)
+	if err := restored.Validate(); err != nil {
+		t.Fatal(err)
+	}
+	for _, definition := range []Definition{restored.Resolved, restored.Version.Definition} {
+		if definition.Tools.Members[0].Optional || !definition.Tools.Members[1].Optional {
+			t.Fatalf("tool requirements changed during binding roundtrip: %+v", definition.Tools)
+		}
+	}
+	restored.Resolved.Tools.Members[1].Optional = false
+	if !errors.Is(restored.Validate(), ErrInvalid) {
+		t.Fatal("changing optional requirement did not invalidate binding digest")
+	}
+}
+
+func TestAbsentOptionalPreservesRevisionAndBindingDigest(t *testing.T) {
+	// A legacy declaration has no optional field; false must keep that encoding.
+	d := Builtins()[0]
+	d.Tools = Selection{Mode: Select, Members: []Module{{ID: "bash"}}}
+	data, err := json.Marshal(d)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var legacy map[string]json.RawMessage
+	if err := json.Unmarshal(data, &legacy); err != nil {
+		t.Fatal(err)
+	}
+	legacy["tools"] = json.RawMessage(`{"mode":"select","members":[{"id":"bash"}]}`)
+	if Revision(d) != Digest(legacy) {
+		t.Fatal("absent optional changed legacy revision")
+	}
+	decoded, err := Decode(data)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if decoded.Tools.Members[0].Optional {
+		t.Fatal("explicit tool became optional by default")
+	}
+	binding := Binding{Resolved: decoded, Version: Version{Definition: decoded, Revision: Revision(decoded)}}
+	binding.Seal()
+	var legacyBinding map[string]json.RawMessage
+	data, err = json.Marshal(binding)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := json.Unmarshal(data, &legacyBinding); err != nil {
+		t.Fatal(err)
+	}
+	legacyData, err := json.Marshal(legacy)
+	if err != nil {
+		t.Fatal(err)
+	}
+	legacyBinding["resolved"] = legacyData
+	versionData, err := json.Marshal(map[string]any{"definition": legacy, "revision": Revision(decoded)})
+	if err != nil {
+		t.Fatal(err)
+	}
+	legacyBinding["version"] = versionData
+	legacyBinding["digest"] = json.RawMessage(`""`)
+	if binding.Digest != Digest(legacyBinding) {
+		t.Fatal("absent optional changed legacy binding digest")
+	}
+}

internal/frontend/serve/agent_presets.go

@@ -204,6 +204,9 @@ func (s *Server) importAgentPreset(w http.ResponseWriter, r *http.Request) {
 	selections := map[string]agentcomposition.Selection{"tools": d.Tools, "skills": d.Skills, "mcp": d.MCP, "extensions": d.Extensions, "hooks": d.Hooks, "commands": d.Commands}
 	for kind, selection := range selections {
 		for _, m := range selection.Members {
+			if m.Optional {
+				continue
+			}
 			if !slices.ContainsFunc(catalog.Modules[kind], func(available agentpreset.Choice) bool { return available.ID == m.ID }) {
 				diagnostics = append(diagnostics, agentcomposition.Diagnostic{Code: "agent_composition.unavailable", Module: kind + ":" + m.ID, Detail: "Dependency is not available on this host."})
 			}

internal/frontend/serve/agent_presets_test.go

@@ -40,3 +40,38 @@ func TestAgentPresetRoutesKeepRevisionsAndRejectStaleWrites(t *testing.T) {
 		t.Fatal("version missing")
 	}
 }
+
+func TestAgentPresetImportOnlyReportsMissingRequiredTools(t *testing.T) {
+	s := newProviderEditServer(t)
+	s.AllowProviderEdit()
+	srv := httptest.NewServer(operatorHandler(s))
+	defer srv.Close()
+	for _, optional := range []bool{false, true} {
+		d := agentcomposition.Builtins()[0]
+		d.ID = "user:imported"
+		d.Tools = agentcomposition.Selection{Mode: agentcomposition.Select, Members: []agentcomposition.Module{{ID: "unavailable-image-reader", Optional: optional}}}
+		body, err := json.Marshal(map[string]any{"content": d})
+		if err != nil {
+			t.Fatal(err)
+		}
+		resp := postProvider(t, srv.URL, "/agent-presets/import", string(body))
+		var preview struct {
+			Diagnostics []agentcomposition.Diagnostic `json:"diagnostics"`
+		}
+		err = json.NewDecoder(resp.Body).Decode(&preview)
+		resp.Body.Close()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if resp.StatusCode != http.StatusOK {
+			t.Fatalf("optional=%v: import status %d", optional, resp.StatusCode)
+		}
+		if optional {
+			if len(preview.Diagnostics) != 0 {
+				t.Fatalf("optional tool refused: %+v", preview.Diagnostics)
+			}
+		} else if len(preview.Diagnostics) != 1 || preview.Diagnostics[0].Code != "agent_composition.unavailable" || preview.Diagnostics[0].Module != "tools:unavailable-image-reader" {
+			t.Fatalf("required tool diagnostic = %+v", preview.Diagnostics)
+		}
+	}
+}