8 files changed, 845 insertions, 81 deletions
diff --git a/src/features/chat/index.ts b/src/features/chat/index.ts
index 6de8164..59da39b 100644
--- a/src/features/chat/index.ts
+++ b/src/features/chat/index.ts
@@ -2,7 +2,7 @@ export type {
   ProviderRetryView,
   RenderedChunk,
   RenderGroup,
-  ToolBatchEntry,
+  ToolEntry,
 } from "../../core/chunks";
 export { groupRenderedChunks, resolveImageUrl, viewProviderRetry } from "../../core/chunks";
 export type { TurnMetricsEntry } from "../../core/metrics";
diff --git a/src/features/chat/logic/tool-summary.test.ts b/src/features/chat/logic/tool-summary.test.ts
new file mode 100644
index 0000000..5caa1f1
--- /dev/null
+++ b/src/features/chat/logic/tool-summary.test.ts
@@ -0,0 +1,281 @@
+import { describe, expect, it } from "vitest";
+import type { ToolEntry } from "../../../core/chunks";
+import { viewToolEntry } from "./tool-summary";
+
+function entry(
+  name: string,
+  input: unknown,
+  content: string | null = "ok",
+  isError = false,
+): ToolEntry {
+  return {
+    toolCallId: "a",
+    toolName: name,
+    call: { type: "tool-call", toolCallId: "a", toolName: name, input },
+    result:
+      content === null
+        ? null
+        : { type: "tool-result", toolCallId: "a", toolName: name, content, isError },
+  };
+}
+
+const view = (name: string, input: unknown, content: string | null = "ok", isError = false) =>
+  viewToolEntry(entry(name, input, content, isError));
+const lines = (n: number) => Array.from({ length: n }, (_, i) => `line ${i + 1}`);
+
+describe("tool summaries", () => {
+  it.each([
+    ["run_shell", { command: "bun run test\n  --run" }, "bun run test --run"],
+    ["read_file", { path: "src/a.ts", offset: 5, limit: 80 }, "src/a.ts:5-84"],
+    ["read_file", { path: "src/a.ts", limit: 12 }, "src/a.ts:1-12"],
+    ["read_file", { path: "src/a.ts", offset: 10 }, "src/a.ts:10"],
+    ["read_file", { path: "src/a.ts" }, "src/a.ts"],
+    ["edit_file", { path: "src/a.ts", oldString: "a", newString: "b" }, "src/a.ts"],
+    ["write_file", { path: "src/a.ts", content: "data" }, "src/a.ts"],
+    ["web_search", { query: "svelte 5 runes", url: "ignored" }, "svelte 5 runes"],
+    ["web_search", { url: "https://example.org", mode: "scrape" }, "https://example.org"],
+    [
+      "lsp",
+      { operation: "references", path: "src/a.ts", line: 12, character: 3 },
+      "references src/a.ts:12:3",
+    ],
+    ["lsp", { operation: "diagnostics", path: "src/a.ts" }, "diagnostics src/a.ts"],
+    [
+      "todo_write",
+      { todos: [{ status: "pending" }, { status: "completed" }, null] },
+      "3 tasks · 1 completed",
+    ],
+    ["load_skill", { name: "research_methodology" }, "research_methodology"],
+    [
+      "consult_vision",
+      { question: "What is in this picture?", imageIds: [1] },
+      "What is in this picture?",
+    ],
+    ["youtube_transcript", { url: "https://youtu.be/abc" }, "https://youtu.be/abc"],
+    ["summon_agent", { title: "Review", task: "long task", agent: "Opus" }, "Review"],
+    ["summon_agent", { task: "Review the patch" }, "Review the patch"],
+    ["summon_agent", { agent: "Opus" }, "Opus"],
+    ["send_agent_message", { conversationId: "abcd", message: "Continue" }, "abcd"],
+    ["read_agent", { conversationId: "abcd" }, "abcd"],
+    ["open_agent", { conversationId: "abcd" }, "abcd"],
+    ["cancel_agent_message", { conversationId: "abcd", messageId: "m1" }, "abcd"],
+    ["list_agents", { relationship: "descendants" }, "descendants"],
+    ["list_agents", { query: "review" }, "review"],
+    ["list_agent_models", { query: "Opus" }, "Opus"],
+  ])("%s derives a meaningful call summary from %j", (name, input, expected) => {
+    expect(view(name, input).callSummary).toBe(expected);
+  });
+
+  it("formats edit call badges and old/new details without hiding multiline text", () => {
+    const input = { path: "a.ts", oldString: "a\nb\n", newString: "x\ny\nz\n" };
+    const card = view("edit_file", input);
+    expect(card.callBadges).toEqual(["+3 −2"]);
+    expect(card.callDetail).toEqual({
+      kind: "edit",
+      path: "a.ts",
+      oldText: input.oldString,
+      newText: input.newString,
+    });
+    expect(view("edit_file", { path: "a", oldString: "", newString: "x" }).callBadges).toEqual([
+      "+1 −0",
+    ]);
+    expect(view("edit_file", { path: "a" }).callBadges).toEqual([]);
+  });
+  it("preserves exact shell commands in the expanded detail", () => {
+    expect(view("run_shell", { command: "ls\n pwd" }).callDetail).toEqual({
+      kind: "command",
+      text: "ls\n pwd",
+    });
+  });
+  it("shows scalar fields and pretty nested JSON", () => {
+    expect(view("mcp__foo", { path: "a.ts", count: 2, nested: { a: true } }).callDetail).toEqual({
+      kind: "fields",
+      fields: [
+        { key: "path", value: "a.ts", multiline: false },
+        { key: "count", value: "2", multiline: false },
+        { key: "nested", value: '{\n  "a": true\n}', multiline: true },
+      ],
+    });
+  });
+  it.each([
+    "command",
+    "path",
+    "file_path",
+    "query",
+    "url",
+    "pattern",
+    "name",
+    "question",
+    "title",
+    "task",
+    "message",
+    "conversationId",
+  ])("generic fallback recognizes %s", (key) => {
+    expect(view("mcp__foo", { [key]: "target" }).callSummary).toBe("target");
+  });
+  it("generic fallback prefers the first meaningful argument, else compact JSON", () => {
+    expect(view("mcp__foo", { command: " ", path: "a", query: "b" }).callSummary).toBe("a");
+    expect(view("mcp__foo", { a: 1, b: "x" }).callSummary).toBe('{"a":1,"b":"x"}');
+  });
+  it.each([
+    "not JSON",
+    "{bad",
+    null,
+    undefined,
+    42,
+    true,
+    [1, "a"],
+    {},
+    "null",
+    '"hi"',
+  ])("tolerates malformed/non-object input %j", (input) => {
+    expect(() => view("read_file", input)).not.toThrow();
+    expect(view("read_file", input).callSummary).not.toBe("");
+    expect(view("read_file", input).callDetail.kind).toBe("fields");
+  });
+  it.each([
+    "run_shell",
+    "read_file",
+    "edit_file",
+    "write_file",
+    "web_search",
+    "lsp",
+    "todo_write",
+    "load_skill",
+    "consult_vision",
+    "youtube_transcript",
+    "summon_agent",
+    "read_agent",
+  ])("%s falls back safely for missing arguments", (name) => {
+    for (const input of [null, undefined, {}, "{bad"]) {
+      expect(() => view(name, input)).not.toThrow();
+      expect(view(name, input).callSummary.trim()).not.toBe("");
+    }
+  });
+  it("parses JSON-string inputs", () => {
+    const card = view("run_shell", '{"command":"bun run test"}');
+    expect(card.callSummary).toBe("bun run test");
+    expect(card.callDetail).toEqual({ kind: "command", text: "bun run test" });
+  });
+  it("handles unexpected built-in argument types and prototype-looking tool names", () => {
+    expect(view("todo_write", { todos: "wrong" }).callSummary).toBe('{"todos":"wrong"}');
+    expect(view("run_shell", { command: { nested: true } }).callDetail.kind).toBe("fields");
+    expect(view("constructor", { path: "a" }).callSummary).toBe("a");
+    expect(view("__proto__", {}).callSummary).toBe("{}");
+    expect(
+      view("mcp", JSON.parse('{"__proto__":{"command":"bad"},"path":"good"}')).callSummary,
+    ).toBe("good");
+  });
+  it("does not throw on unserializable input", () => {
+    const cyclic: Record<string, unknown> = {};
+    cyclic.self = cyclic;
+    expect(view("mcp", cyclic).callSummary).toBe("[unserializable input]");
+    expect(() => view("mcp", { integer: 1n })).not.toThrow();
+  });
+  it("caps and whitespace-collapses header strings but retains full detail", () => {
+    const command = `  echo\n${"x".repeat(300)}`;
+    const card = view("run_shell", { command });
+    expect(card.callSummary.length).toBe(120);
+    expect(card.callSummary.endsWith("…")).toBe(true);
+    expect(card.callSummary).not.toMatch(/\n/);
+    expect(card.callDetail).toEqual({ kind: "command", text: command });
+  });
+  it("represents pending entries with no response summary/output", () => {
+    expect(view("run_shell", { command: "sleep 1" }, null)).toMatchObject({
+      status: "pending",
+      resultSummary: null,
+      output: null,
+    });
+  });
+  it("represents orphan results with unknown call details, not pending", () => {
+    const e = { ...entry("read_file", {}, "data"), call: null };
+    expect(viewToolEntry(e)).toMatchObject({
+      name: "read_file",
+      status: "ok",
+      callSummary: "call unavailable",
+      resultSummary: "1 line",
+    });
+    expect(viewToolEntry(e).callDetail).toEqual({
+      kind: "fields",
+      fields: [
+        { key: "call", value: "Call unavailable (earlier history unloaded)", multiline: false },
+      ],
+    });
+  });
+});
+
+describe("tool response facts", () => {
+  it.each([
+    ["run_shell", "one\ntwo\n", false, "2 lines"],
+    ["run_shell", "done", false, "1 line"],
+    ["read_file", "1\tfile text\n", false, "1 line"],
+    ["read_file", "(empty file: a.ts)", false, "empty file"],
+    ["mcp", "", false, "no output"],
+    ["mcp", " \n\t", false, "no output"],
+    ["mcp", "a short response", false, "a short response"],
+    ["mcp", "x".repeat(200), false, "1 line"],
+    ["web_search", "a\nb\nc", false, "3 lines"],
+    ["run_shell", "", true, "failed"],
+    ["mcp", "Permission denied", true, "failed · Permission denied"],
+    ["run_shell", "error\ndetail", true, "failed · 2 lines"],
+    ["run_shell", "partial\n\n[Command timed out]", true, "timed out"],
+    ["run_shell", "[Output truncated: 12000 bytes]", false, "1 line · truncated"],
+    ["run_shell", "bad\n[Output truncated: 12000 bytes]", true, "failed · 2 lines · truncated"],
+    ["edit_file", 'Replaced 1 occurrence(s) in "a.ts".', false, "1 replacement"],
+    [
+      "edit_file",
+      'Replaced 3 occurrences in "a.ts".\n\nLSP diagnostics: error at line 2',
+      false,
+      "3 replacements · diagnostics",
+    ],
+    ["write_file", 'Created "a.ts" (4200 bytes).', false, "created · 4.1 KB"],
+    ["write_file", 'Overwrote "a.ts" (10 bytes).', false, "overwrote · 10 B"],
+    ["write_file", 'Created "a.ts" (1048576 bytes).', false, "created · 1.0 MB"],
+  ])("%s summarizes %j (error=%s)", (name, content, isError, expected) => {
+    const card = view(name, {}, content, isError);
+    expect(card.resultSummary).toBe(expected);
+    expect(card.status).toBe(isError ? "error" : "ok");
+    expect(card.output?.isError).toBe(isError);
+  });
+  it("does not infer success on an error that resembles a write result", () => {
+    expect(view("write_file", {}, 'Created "a.ts" (10 bytes).', true).resultSummary).toMatch(
+      /^failed/,
+    );
+  });
+});
+
+describe("tool output elision", () => {
+  it.each([0, 1, 6, 11, 12])("shows %i lines in full", (n) => {
+    expect(view("mcp", {}, lines(n).join("\n")).output).toEqual({
+      kind: "full",
+      lines: lines(n),
+      isError: false,
+    });
+  });
+  it.each([
+    13, 14, 100,
+  ])("shows first/last six of %i lines, retaining everything for expansion", (n) => {
+    expect(view("mcp", {}, lines(n).join("\n"), true).output).toEqual({
+      kind: "elided",
+      head: lines(n).slice(0, 6),
+      hiddenCount: n - 12,
+      tail: lines(n).slice(-6),
+      all: lines(n),
+      isError: true,
+    });
+  });
+  it("ignores one final newline terminator at the 12/13 boundary (including CRLF)", () => {
+    expect(view("mcp", {}, `${lines(12).join("\r\n")}\r\n`).output?.kind).toBe("full");
+    expect(view("mcp", {}, `${lines(13).join("\n")}\n`).output).toMatchObject({
+      kind: "elided",
+      hiddenCount: 1,
+    });
+  });
+  it("preserves meaningful blank lines including an extra trailing blank line", () => {
+    expect(view("mcp", {}, "a\n\nb\n\n").output).toEqual({
+      kind: "full",
+      lines: ["a", "", "b", ""],
+      isError: false,
+    });
+  });
+});
diff --git a/src/features/chat/logic/tool-summary.ts b/src/features/chat/logic/tool-summary.ts
new file mode 100644
index 0000000..3b75a6b
--- /dev/null
+++ b/src/features/chat/logic/tool-summary.ts
@@ -0,0 +1,263 @@
+import type { ToolEntry } from "../../../core/chunks";
+
+export interface ToolCardView {
+  readonly name: string;
+  readonly status: "pending" | "ok" | "error";
+  readonly callSummary: string;
+  readonly callBadges: readonly string[];
+  readonly resultSummary: string | null;
+  readonly callDetail:
+    | { readonly kind: "command"; readonly text: string }
+    | {
+        readonly kind: "edit";
+        readonly path: string;
+        readonly oldText: string;
+        readonly newText: string;
+      }
+    | {
+        readonly kind: "fields";
+        readonly fields: readonly {
+          readonly key: string;
+          readonly value: string;
+          readonly multiline: boolean;
+        }[];
+      };
+  readonly output: ToolOutputView | null;
+}
+
+export type ToolOutputView =
+  | { readonly kind: "full"; readonly lines: readonly string[]; readonly isError: boolean }
+  | {
+      readonly kind: "elided";
+      readonly head: readonly string[];
+      readonly hiddenCount: number;
+      readonly tail: readonly string[];
+      readonly all: readonly string[];
+      readonly isError: boolean;
+    };
+
+type Args = Readonly<Record<string, unknown>>;
+type CallSummary = (args: Args) => string;
+
+function oneLine(text: string, cap = 120): string {
+  const compact = text.replace(/\s+/g, " ").trim();
+  return compact.length > cap ? `${compact.slice(0, cap - 1)}…` : compact;
+}
+
+function normalize(input: unknown): unknown {
+  if (typeof input !== "string") return input;
+  try {
+    return JSON.parse(input);
+  } catch {
+    return input;
+  }
+}
+
+function asArgs(input: unknown): Args {
+  return typeof input === "object" && input !== null && !Array.isArray(input)
+    ? (input as Args)
+    : {};
+}
+
+function serialize(input: unknown, pretty = false): string {
+  if (typeof input === "string") return input;
+  try {
+    return JSON.stringify(input, null, pretty ? 2 : undefined) ?? String(input);
+  } catch {
+    return "[unserializable input]";
+  }
+}
+
+function arg(args: Args, ...keys: string[]): string {
+  for (const key of keys) {
+    const value = Object.hasOwn(args, key) ? args[key] : undefined;
+    if (typeof value === "string" && value.trim()) return value;
+    if (typeof value === "number" || typeof value === "boolean") return String(value);
+  }
+  return "";
+}
+
+function lineCount(text: string): number {
+  return text === "" ? 0 : outputLines(text).length;
+}
+
+/** Drop one final newline terminator, not meaningful blank lines within the output. */
+function outputLines(content: string): string[] {
+  const normalized = content.replace(/\r\n/g, "\n");
+  return normalized === "" ? [] : normalized.replace(/\n$/, "").split("\n");
+}
+
+function readSummary(args: Args): string {
+  const path = arg(args, "path");
+  const offset = typeof args.offset === "number" && Number.isFinite(args.offset) ? args.offset : 1;
+  const limit = typeof args.limit === "number" && Number.isFinite(args.limit) ? args.limit : null;
+  return `${path}${limit !== null ? `:${offset}-${offset + limit - 1}` : args.offset !== undefined ? `:${offset}` : ""}`;
+}
+
+function lspSummary(args: Args): string {
+  const line = arg(args, "line");
+  const character = arg(args, "character");
+  return `${arg(args, "operation")} ${arg(args, "path")}${line ? `:${line}${character ? `:${character}` : ""}` : ""}`;
+}
+
+function todoSummary(args: Args): string {
+  if (!Array.isArray(args.todos)) return "";
+  const done = args.todos.filter((t) => asArgs(t).status === "completed").length;
+  return `${args.todos.length} tasks · ${done} completed`;
+}
+
+const summarizeAgent: CallSummary = (args) => arg(args, "title", "task", "agent", "model");
+const summarizeConversation: CallSummary = (args) => arg(args, "conversationId", "message");
+
+/** Optional built-in polish; all unknown/MCP names use the same generic path. */
+const summaries: Readonly<Record<string, CallSummary>> = {
+  run_shell: (args) => arg(args, "command"),
+  read_file: readSummary,
+  edit_file: (args) => arg(args, "path"),
+  write_file: (args) => arg(args, "path"),
+  web_search: (args) => arg(args, "query", "url"),
+  lsp: lspSummary,
+  todo_write: todoSummary,
+  load_skill: (args) => arg(args, "name"),
+  consult_vision: (args) => arg(args, "question", "path"),
+  youtube_transcript: (args) => arg(args, "url"),
+  summon_agent: summarizeAgent,
+  send_agent_message: summarizeConversation,
+  read_agent: summarizeConversation,
+  open_agent: summarizeConversation,
+  cancel_agent_message: summarizeConversation,
+  list_agents: (args) => arg(args, "query", "relationship", "workspaceId"),
+  list_agent_models: (args) => arg(args, "query"),
+};
+
+function detail(name: string, input: unknown, args: Args): ToolCardView["callDetail"] {
+  if (name === "run_shell" && typeof args.command === "string") {
+    return { kind: "command", text: args.command };
+  }
+  if (name === "edit_file" && typeof args.path === "string") {
+    return {
+      kind: "edit",
+      path: args.path,
+      oldText: typeof args.oldString === "string" ? args.oldString : "",
+      newText: typeof args.newString === "string" ? args.newString : "",
+    };
+  }
+  const entries = Object.entries(args);
+  return {
+    kind: "fields",
+    fields: (entries.length > 0 ? entries : [["input", input]]).map(([key, value]) => {
+      const text = serialize(value, true);
+      return { key: String(key), value: text, multiline: text.includes("\n") };
+    }),
+  };
+}
+
+function bytesLabel(bytes: number): string {
+  if (bytes < 1024) return `${bytes} B`;
+  if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(1)} KB`;
+  return `${(bytes / (1024 * 1024)).toFixed(1)} MB`;
+}
+
+function responseSummary(name: string, content: string, isError: boolean): string {
+  const lines = outputLines(content);
+  const first = oneLine(lines.find((line) => line.trim()) ?? "", 72);
+  const count = `${lines.length} ${lines.length === 1 ? "line" : "lines"}`;
+  const timeout = /\[Command timed out\]/i.test(content);
+  const truncated = /\[Output truncated[^\]]*\]/i.test(content);
+  let summary: string;
+  if (timeout) summary = "timed out";
+  else if (isError)
+    summary = `failed${lines.length > 1 ? ` · ${count}` : first ? ` · ${first}` : ""}`;
+  else if (!content.trim()) summary = "no output";
+  else if (/^\(empty file\b/i.test(content)) summary = "empty file";
+  else {
+    const replaced =
+      name === "edit_file" ? /^Replaced (\d+) occurrence(?:\(s\)|s)?/i.exec(content) : null;
+    const written =
+      name === "write_file" ? /^(Created|Overwrote)\b[^\n]*\((\d+) bytes\)/i.exec(content) : null;
+    if (replaced) {
+      summary = `${replaced[1]} ${replaced[1] === "1" ? "replacement" : "replacements"}`;
+      if (content.trim().includes("\n")) summary += " · diagnostics";
+    } else if (written) {
+      summary = `${written[1]?.toLowerCase()} · ${bytesLabel(Number(written[2]))}`;
+    } else if (
+      name === "run_shell" ||
+      name === "read_file" ||
+      lines.length > 1 ||
+      first.length > 60
+    ) {
+      summary = count;
+    } else summary = first;
+  }
+  return oneLine(`${summary}${truncated ? " · truncated" : ""}`, 96);
+}
+
+export function viewToolEntry(entry: ToolEntry): ToolCardView {
+  const input = normalize(entry.call?.input);
+  const args = asArgs(input);
+  const summarize = Object.hasOwn(summaries, entry.toolName)
+    ? summaries[entry.toolName]
+    : undefined;
+  const generic = arg(
+    args,
+    "command",
+    "path",
+    "file_path",
+    "query",
+    "url",
+    "pattern",
+    "name",
+    "question",
+    "title",
+    "task",
+    "message",
+    "conversationId",
+  );
+  const builtInSummary = summarize?.(args).trim();
+  const callSummary =
+    entry.call === null
+      ? "call unavailable"
+      : oneLine(builtInSummary || generic || serialize(input));
+  const callBadges: string[] = [];
+  if (entry.toolName === "edit_file" && entry.call !== null) {
+    if (typeof args.oldString === "string" && typeof args.newString === "string") {
+      callBadges.push(`+${lineCount(args.newString)} −${lineCount(args.oldString)}`);
+    }
+  }
+  const result = entry.result;
+  const lines = result === null ? [] : outputLines(result.content);
+  return {
+    name: entry.toolName,
+    status: result === null ? "pending" : result.isError ? "error" : "ok",
+    callSummary,
+    callBadges,
+    callDetail:
+      entry.call === null
+        ? {
+            kind: "fields",
+            fields: [
+              {
+                key: "call",
+                value: "Call unavailable (earlier history unloaded)",
+                multiline: false,
+              },
+            ],
+          }
+        : detail(entry.toolName, input, args),
+    resultSummary:
+      result === null ? null : responseSummary(entry.toolName, result.content, result.isError),
+    output:
+      result === null
+        ? null
+        : lines.length <= 12
+          ? { kind: "full", lines, isError: result.isError }
+          : {
+              kind: "elided",
+              head: lines.slice(0, 6),
+              hiddenCount: lines.length - 12,
+              tail: lines.slice(-6),
+              all: lines,
+              isError: result.isError,
+            },
+  };
+}
diff --git a/src/features/chat/ui.test.ts b/src/features/chat/ui.test.ts
index 3c7fd0d..c3a76d4 100644
--- a/src/features/chat/ui.test.ts
+++ b/src/features/chat/ui.test.ts
@@ -210,7 +210,7 @@ describe("ChatView", () => {
     expect(log.children).toHaveLength(0);
   });
 
-  it("groups batched tool calls (shared stepId) into one DaisyUI list", async () => {
+  it("renders parallel tool calls (shared stepId) as separate bubbles", async () => {
     const chunks: RenderedChunk[] = [
       {
         seq: 1,
@@ -254,10 +254,12 @@ describe("ChatView", () => {
     const { container } = render(ChatView, { props: { chunks } });
     await openAllCollapses(container);
 
-    // Batched calls render as collapsible cards (one per call), not a list.
+    // Parallel calls render as independent collapsible cards (one per bubble).
     const collapses = container.querySelectorAll(".collapse");
     expect(collapses).toHaveLength(2);
 
+    expect(container.querySelectorAll(".chat-bubble")).toHaveLength(2);
+
     // Both call names + the available result are shown; the result is absorbed
     // (no standalone tool-result card).
     expect(screen.getByText("read_file")).toBeInTheDocument();
diff --git a/src/features/chat/ui/ChatView.svelte b/src/features/chat/ui/ChatView.svelte
index 5e4513c..18fea7c 100644
--- a/src/features/chat/ui/ChatView.svelte
+++ b/src/features/chat/ui/ChatView.svelte
@@ -11,6 +11,7 @@
   } from "../../../core/metrics";
   import { Markdown } from "../../markdown";
   import LazyCollapse from "./LazyCollapse.svelte";
+  import ToolCard from "./ToolCard.svelte";
 
   const badgeClass = {
     success: "badge-success",
@@ -73,6 +74,7 @@
 
   const rows = $derived(interleaveTurnMetrics(groups, turnMetrics));
 
+  // Tool cards use toolCallId keys across pending/result/seal and orphan page-in.
   // Stable per-row keys. Thinking blocks get an ordinal key (`think<n>`) that
   // survives the provisional→committed (seq null → seq N) transition, so the
   // collapse's open/close state is NOT lost when a turn seals. The ordinal
@@ -89,8 +91,8 @@
       }
       const group = row.group;
       let key: string;
-      if (group.kind === "tool-batch") {
-        key = `b${group.stepId}`;
+      if (group.kind === "tool") {
+        key = `t${group.entry.toolCallId}`;
       } else if (group.chunk.chunk.type === "thinking") {
         key = `think${thinking++}`;
       } else if (group.chunk.seq != null) {
@@ -103,22 +105,6 @@
   });
 </script>
 
-{#snippet wrench()}
-  <svg
-    class="h-4 w-4 opacity-60"
-    xmlns="http://www.w3.org/2000/svg"
-    viewBox="0 0 24 24"
-    fill="none"
-    stroke="currentColor"
-    stroke-width="2"
-    stroke-linecap="round"
-    stroke-linejoin="round"
-    ><path
-      d="M14.7 6.3a1 1 0 0 0 0 1.4l1.6 1.6a1 1 0 0 0 1.4 0l3.77-3.77a6 6 0 0 1-7.94 7.94l-6.91 6.91a2.12 2.12 0 0 1-3-3l6.91-6.91a6 6 0 0 1 7.94-7.94l-3.76 3.76z"
-    /></svg
-  >
-{/snippet}
-
 {#snippet chunkRow(rendered: RenderedChunk)}
   {#if rendered.role === "user"}
     <!-- User: a speech bubble, left-aligned. A user message may be multi-chunk
@@ -158,36 +144,6 @@
         </LazyCollapse>
       </div>
     </div>
-  {:else if rendered.chunk.type === "tool-call" || rendered.chunk.type === "tool-result"}
-    <!-- Single tool call/result: a collapsible card (collapsed by default,
-         like thinking). Title shows the tool name; content shows the
-         input/output. Same chat-start grid shim as the thinking block. -->
-    <div class="chat chat-start [&>.chat-bubble]:max-w-5xl [&>.chat-bubble]:p-0">
-      <div class="chat-bubble w-full bg-transparent">
-        {#if rendered.chunk.type === "tool-call"}
-          {@const call = rendered.chunk}
-          <LazyCollapse label="Toggle tool call">
-            {#snippet title()}
-              {@render wrench()}
-              <span>{call.toolName}</span>
-            {/snippet}
-            <pre class="overflow-x-auto text-xs">{JSON.stringify(call.input, null, 2)}</pre>
-          </LazyCollapse>
-        {:else}
-          {@const res = rendered.chunk}
-          <LazyCollapse label="Toggle tool result" titleClass={res.isError ? "text-error" : ""}>
-            {#snippet title()}
-              {@render wrench()}
-              <span>{res.toolName}</span>
-              {#if res.isError}
-                <span class="badge badge-error badge-xs">error</span>
-              {/if}
-            {/snippet}
-            <pre class="max-h-96 overflow-auto text-xs">{res.content}</pre>
-          </LazyCollapse>
-        {/if}
-      </div>
-    </div>
   {:else}
     <!-- Assistant text / system / error: an INVISIBLE speech bubble — same
          chat-start grid as the user bubble, so it inherits identical left spacing. -->
@@ -287,31 +243,10 @@
     {:else if row.group.kind === "single"}
       {@render chunkRow(row.group.chunk)}
     {:else}
-      <!-- Batched tool calls (one step): each entry is a collapsible card.
-           Click to expand and see the input/output. -->
-      <div class="chat chat-start [&>.chat-bubble]:max-w-5xl [&>.chat-bubble]:p-0">
-        <div class="chat-bubble w-full bg-transparent">
-          <div class="flex flex-col gap-1">
-            {#each row.group.entries as entry, entryIndex (entryIndex)}
-              <LazyCollapse label="Toggle tool call">
-                {#snippet title()}
-                  {@render wrench()}
-                  <span>{entry.call.toolName}</span>
-                  {#if entry.result?.isError}
-                    <span class="badge badge-error badge-xs">error</span>
-                  {:else if entry.result === null}
-                    <span class="loading loading-spinner loading-xs" aria-label="Running"></span>
-                  {/if}
-                {/snippet}
-                <pre class="overflow-x-auto text-xs">{JSON.stringify(entry.call.input, null, 2)}</pre>
-                {#if entry.result}
-                  <pre
-                    class="mt-1 max-h-96 overflow-auto text-xs"
-                    class:text-error={entry.result.isError}>{entry.result.content}</pre>
-                {/if}
-              </LazyCollapse>
-            {/each}
-          </div>
+      <!-- Each call owns one bubble; the matching result is folded into its card. -->
+      <div class="chat chat-start [grid-template-columns:auto_minmax(0,1fr)] [&>.chat-bubble]:max-w-5xl [&>.chat-bubble]:p-0">
+        <div class="chat-bubble min-w-0 w-full bg-transparent">
+          <ToolCard entry={row.group.entry} />
         </div>
       </div>
     {/if}
diff --git a/src/features/chat/ui/ChatView.test.ts b/src/features/chat/ui/ChatView.test.ts
index fcac312..d12088b 100644
--- a/src/features/chat/ui/ChatView.test.ts
+++ b/src/features/chat/ui/ChatView.test.ts
@@ -19,7 +19,7 @@ async function openAllCollapses(container: HTMLElement): Promise<void> {
 // Svelte `each_key_duplicate` (which aborts the reactive flush and makes the
 // tab appear dead). See fix-toolcall-duplicate-keys plan Part 1.
 describe("ChatView — duplicate toolCallIds", () => {
-  it("renders a tool batch with duplicated toolCallIds without throwing, showing one card per unique call", async () => {
+  it("renders duplicated toolCallIds without throwing, showing one bubble per unique call", async () => {
     const chunks: RenderedChunk[] = [
       {
         seq: 1,
@@ -96,7 +96,7 @@ describe("ChatView — duplicate toolCallIds", () => {
         },
         provisional: false,
       },
-      // Duplicate results too — absorbed into the single deduped batch.
+      // Duplicate results too — absorbed into the corresponding cards.
       {
         seq: 7,
         role: "tool",
@@ -128,10 +128,11 @@ describe("ChatView — duplicate toolCallIds", () => {
     const { container } = render(ChatView, { props: { chunks } });
     await openAllCollapses(container);
 
-    // No each_key_duplicate crash. Batched calls render as collapsible cards —
+    // No each_key_duplicate crash. Calls render as independent collapsible cards —
     // exactly ONE per unique toolCallId (deduped), not 4.
     const collapses = container.querySelectorAll(".collapse");
     expect(collapses).toHaveLength(2);
+    expect(container.querySelectorAll(".chat-bubble")).toHaveLength(2);
 
     // Both unique tool names shown; each result rendered once (deduped).
     expect(screen.getByText("read_file")).toBeInTheDocument();
@@ -161,7 +162,7 @@ describe("ChatView — lazy collapse bodies", () => {
     expect(screen.getByText("run_shell")).toBeInTheDocument();
     expect(screen.queryByText("HUGE-OUTPUT")).toBeNull();
 
-    const box = screen.getByRole("checkbox", { name: "Toggle tool result" });
+    const box = screen.getByRole("checkbox", { name: "Toggle tool call run_shell" });
     await userEvent.click(box);
     expect(screen.getByText("HUGE-OUTPUT")).toBeInTheDocument();
 
@@ -170,3 +171,174 @@ describe("ChatView — lazy collapse bodies", () => {
     expect(container.querySelectorAll(".chat-row")).toHaveLength(1);
   });
 });
+
+function shellChunks(content: string | null, isError = false, committed = false): RenderedChunk[] {
+  const call: RenderedChunk = {
+    seq: committed ? 1 : null,
+    role: "assistant",
+    provisional: !committed,
+    chunk: {
+      type: "tool-call",
+      toolCallId: "shell-1",
+      toolName: "run_shell",
+      input: { command: "bun run test" },
+    },
+  };
+  return content === null
+    ? [call]
+    : [
+        call,
+        {
+          seq: committed ? 2 : null,
+          role: "tool",
+          provisional: !committed,
+          chunk: {
+            type: "tool-result",
+            toolCallId: "shell-1",
+            toolName: "run_shell",
+            content,
+            isError,
+          },
+        },
+      ];
+}
+
+describe("ChatView — tool cards", () => {
+  it("pairs a single call/result into one collapsed bubble with both summaries and a success icon", async () => {
+    const { container } = render(ChatView, { props: { chunks: shellChunks("first\nsecond") } });
+    expect(container.querySelectorAll(".chat-bubble")).toHaveLength(1);
+    expect(container.querySelectorAll(".collapse")).toHaveLength(1);
+    expect(screen.getByText("bun run test")).toBeInTheDocument();
+    expect(screen.getByText("→ 2 lines")).toBeInTheDocument();
+    expect(screen.getByLabelText("Succeeded")).toHaveTextContent("✓");
+    const box = screen.getByRole("checkbox", { name: "Toggle tool call run_shell" });
+    expect(box).not.toBeChecked();
+    expect(container.querySelector("pre")).toBeNull();
+    await userEvent.click(box);
+    expect(screen.getByText("$ bun run test")).toBeInTheDocument();
+    expect(screen.getByText("first second")).toBeInTheDocument();
+    expect(screen.queryByRole("checkbox", { name: /tool result/ })).toBeNull();
+  });
+  it("transitions pending → result → sealed without losing open state", async () => {
+    const { container, rerender } = render(ChatView, { props: { chunks: shellChunks(null) } });
+    expect(screen.getByLabelText("Running")).toHaveClass("loading-spinner");
+    expect(container.querySelector(".collapse-title")).not.toHaveTextContent("→");
+    const box = screen.getByRole("checkbox", { name: "Toggle tool call run_shell" });
+    await userEvent.click(box);
+    expect(screen.getByText("running…")).toBeInTheDocument();
+    await rerender({ chunks: shellChunks("done") });
+    expect(screen.queryByLabelText("Running")).toBeNull();
+    expect(screen.getByLabelText("Succeeded")).toBeInTheDocument();
+    expect(screen.getByRole("checkbox", { name: "Toggle tool call run_shell" })).toBe(box);
+    expect(box).toBeChecked();
+    await rerender({ chunks: shellChunks("done", false, true) });
+    expect(screen.getByRole("checkbox", { name: "Toggle tool call run_shell" })).toBe(box);
+    expect(box).toBeChecked();
+    expect(screen.getByText("done")).toBeInTheDocument();
+  });
+  it("keeps errors collapsed with a failure icon and tints the expanded output", async () => {
+    const { container } = render(ChatView, {
+      props: { chunks: shellChunks("Permission denied", true) },
+    });
+    const box = screen.getByRole("checkbox", { name: "Toggle tool call run_shell" });
+    expect(box).not.toBeChecked();
+    expect(screen.getByLabelText("Failed")).toHaveClass("text-error");
+    expect(screen.getByLabelText("Failed")).toHaveTextContent("✗");
+    expect(screen.getByText("→ failed · Permission denied")).toHaveClass("text-error");
+    expect(container.querySelector("pre")).toBeNull();
+    await userEvent.click(box);
+    expect(screen.getByText("Permission denied").parentElement).toHaveClass("text-error");
+  });
+  it("renders an orphan result as the same card and retains state when its call is paged back in", async () => {
+    const chunks = shellChunks("contents", false, true);
+    const { container, rerender } = render(ChatView, { props: { chunks: chunks.slice(1) } });
+    expect(container.querySelectorAll(".chat-bubble")).toHaveLength(1);
+    expect(screen.getByText("call unavailable")).toBeInTheDocument();
+    const box = screen.getByRole("checkbox", { name: "Toggle tool call run_shell" });
+    await userEvent.click(box);
+    expect(screen.getByText(/Call unavailable \(earlier history unloaded\)/)).toBeInTheDocument();
+    expect(screen.getByText("contents")).toBeInTheDocument();
+    await rerender({ chunks });
+    expect(screen.getByRole("checkbox", { name: "Toggle tool call run_shell" })).toBe(box);
+    expect(box).toBeChecked();
+    expect(screen.getByText("$ bun run test")).toBeInTheDocument();
+  });
+  it("folds 13 output lines as 6 + toggle + 6, expands and collapses without closing the card", async () => {
+    const output = Array.from({ length: 13 }, (_, i) => `output-${i + 1}`).join("\n");
+    const { rerender } = render(ChatView, { props: { chunks: shellChunks(output) } });
+    const box = screen.getByRole("checkbox", { name: "Toggle tool call run_shell" });
+    await userEvent.click(box);
+    const response = screen.getByRole("region", { name: "Response" });
+    expect(response).toHaveTextContent("output-1");
+    expect(response).toHaveTextContent("output-6");
+    expect(response).not.toHaveTextContent("output-7");
+    expect(response).toHaveTextContent("output-8");
+    expect(response).toHaveTextContent("output-13");
+    const toggle = screen.getByRole("button", { name: "⋯ 1 more lines" });
+    expect(toggle).toHaveAttribute("aria-expanded", "false");
+    await userEvent.click(toggle);
+    expect(response).toHaveTextContent("output-7");
+    expect(response.querySelectorAll("pre")).toHaveLength(1);
+    expect(response.querySelector("pre")?.textContent).toBe(output);
+    expect(box).toBeChecked();
+    expect(screen.getByRole("button", { name: "Show fewer lines" })).toHaveAttribute(
+      "aria-expanded",
+      "true",
+    );
+    await userEvent.click(screen.getByRole("button", { name: "Show fewer lines" }));
+    expect(response).not.toHaveTextContent("output-7");
+    expect(box).toBeChecked();
+    // The separate output-fold state also survives sealing.
+    await userEvent.click(screen.getByRole("button", { name: "⋯ 1 more lines" }));
+    expect(response).toHaveTextContent("output-7");
+    await rerender({ chunks: shellChunks(output, false, true) });
+    expect(box).toBeChecked();
+    expect(screen.getByRole("button", { name: "Show fewer lines" })).toHaveAttribute(
+      "aria-expanded",
+      "true",
+    );
+    expect(response).toHaveTextContent("output-7");
+  });
+  it("shows 12 output lines without an inner toggle", async () => {
+    const output = Array.from({ length: 12 }, (_, i) => `output-${i + 1}`).join("\n");
+    render(ChatView, { props: { chunks: shellChunks(output) } });
+    await userEvent.click(screen.getByRole("checkbox", { name: "Toggle tool call run_shell" }));
+    expect(screen.queryByRole("button", { name: /more lines|fewer lines/ })).toBeNull();
+    expect(screen.getByRole("region", { name: "Response" })).toHaveTextContent("output-12");
+  });
+  it("renders edit details and treats tool output as text, not executable markup", async () => {
+    const chunks: RenderedChunk[] = [
+      {
+        seq: 1,
+        role: "assistant",
+        provisional: false,
+        chunk: {
+          type: "tool-call",
+          toolCallId: "edit",
+          toolName: "edit_file",
+          input: { path: "a.ts", oldString: "before", newString: "after\nsecond" },
+        },
+      },
+      {
+        seq: 2,
+        role: "tool",
+        provisional: false,
+        chunk: {
+          type: "tool-result",
+          toolCallId: "edit",
+          toolName: "edit_file",
+          content: 'Replaced 1 occurrence(s) in "a.ts".\n<script>alert(1)</script>',
+          isError: false,
+        },
+      },
+    ];
+    const { container } = render(ChatView, { props: { chunks } });
+    expect(screen.getByText("+2 −1")).toBeInTheDocument();
+    expect(screen.getByText("→ 1 replacement · diagnostics")).toBeInTheDocument();
+    await userEvent.click(screen.getByRole("checkbox", { name: "Toggle tool call edit_file" }));
+    expect(screen.getByText("before")).toHaveClass("text-error");
+    expect(screen.getByText("after second")).toHaveClass("text-success");
+    expect(container.querySelector("script")).toBeNull();
+    expect(container).toHaveTextContent("<script>alert(1)</script>");
+  });
+});
diff --git a/src/features/chat/ui/LazyCollapse.svelte b/src/features/chat/ui/LazyCollapse.svelte
index 0f66451..912adb4 100644
--- a/src/features/chat/ui/LazyCollapse.svelte
+++ b/src/features/chat/ui/LazyCollapse.svelte
@@ -33,7 +33,7 @@
 
 <div class="collapse w-full rounded-box bg-base-200 text-sm">
   <input type="checkbox" aria-label={label} bind:checked={open} />
-  <div class="collapse-title flex min-h-0 items-center gap-2 py-2 font-medium {titleClass}">
+  <div class="collapse-title flex min-h-0 min-w-0 items-center gap-2 py-2 whitespace-nowrap font-medium {titleClass}">
     {@render title()}
   </div>
   <div class="collapse-content">
diff --git a/src/features/chat/ui/ToolCard.svelte b/src/features/chat/ui/ToolCard.svelte
new file mode 100644
index 0000000..8c6e325
--- /dev/null
+++ b/src/features/chat/ui/ToolCard.svelte
@@ -0,0 +1,111 @@
+<script lang="ts">
+  import type { ToolEntry } from "../index";
+  import { viewToolEntry } from "../logic/tool-summary";
+  import LazyCollapse from "./LazyCollapse.svelte";
+
+  let { entry }: { entry: ToolEntry } = $props();
+  const card = $derived(viewToolEntry(entry));
+  let showAll = $state(false);
+</script>
+
+<LazyCollapse label={`Toggle tool call ${card.name}`}>
+  {#snippet title()}
+    {#if card.status === "pending"}
+      <span class="loading loading-spinner loading-xs shrink-0" aria-label="Running"></span>
+    {:else if card.status === "error"}
+      <span class="shrink-0 text-error" aria-label="Failed">✗</span>
+    {:else}
+      <span class="shrink-0 text-success" aria-label="Succeeded">✓</span>
+    {/if}
+    <svg
+      class="h-4 w-4 shrink-0 opacity-60"
+      xmlns="http://www.w3.org/2000/svg"
+      viewBox="0 0 24 24"
+      fill="none"
+      stroke="currentColor"
+      stroke-width="2"
+      stroke-linecap="round"
+      stroke-linejoin="round"
+      aria-hidden="true"
+    >
+      <path
+        d="M14.7 6.3a1 1 0 0 0 0 1.4l1.6 1.6a1 1 0 0 0 1.4 0l3.77-3.77a6 6 0 0 1-7.94 7.94l-6.91 6.91a2.12 2.12 0 0 1-3-3l6.91-6.91a6 6 0 0 1 7.94-7.94l-3.76 3.76z"
+      />
+    </svg>
+    <span class="max-w-[35%] shrink-0 truncate" title={card.name}>{card.name}</span>
+    <span class="min-w-0 flex-1 truncate opacity-70" title={card.callSummary}
+      >{card.callSummary}</span
+    >
+    {#each card.callBadges as badge}
+      <span class="shrink-0 text-xs opacity-70">{badge}</span>
+    {/each}
+    {#if card.resultSummary !== null}
+      <span
+        class="max-w-[40%] shrink-0 truncate text-xs"
+        class:text-error={card.status === "error"}
+        title={card.resultSummary}
+      >
+        → {card.resultSummary}
+      </span>
+    {/if}
+  {/snippet}
+  <div class="min-w-0 space-y-3 text-xs">
+    <section aria-label="Call">
+      <div class="mb-1 font-medium opacity-60">Call</div>
+      {#if card.callDetail.kind === "command"}
+        <pre class="overflow-x-auto">$ {card.callDetail.text}</pre>
+      {:else if card.callDetail.kind === "edit"}
+        <div class="mb-1 break-all font-mono">{card.callDetail.path}</div>
+        <div class="space-y-1">
+          <div class="opacity-60">− old</div>
+          <pre class="overflow-x-auto text-error">{card.callDetail.oldText}</pre>
+          <div class="opacity-60">+ new</div>
+          <pre class="overflow-x-auto text-success">{card.callDetail.newText}</pre>
+        </div>
+      {:else}
+        <dl class="space-y-1">
+          {#each card.callDetail.fields as field}
+            <div>
+              <dt class="opacity-60">{field.key}</dt>
+              <dd>
+                <pre
+                  class="overflow-x-auto"
+                  class:whitespace-pre-wrap={!field.multiline}>{field.value}</pre>
+              </dd>
+            </div>
+          {/each}
+        </dl>
+      {/if}
+    </section>
+    <section aria-label="Response">
+      <div class="mb-1 font-medium opacity-60">Response</div>
+      {#if card.output === null}
+        <span class="opacity-60">running…</span>
+      {:else}
+        <div class:text-error={card.output.isError}>
+          {#if card.output.kind === "full"}
+            <pre class="overflow-x-auto">{card.output.lines.join("\n") || "(no output)"}</pre>
+          {:else}
+            {#if showAll}
+              <pre class="overflow-x-auto">{card.output.all.join("\n")}</pre>
+            {:else}
+              <pre class="overflow-x-auto">{card.output.head.join("\n")}</pre>
+            {/if}
+            <button
+              class="btn btn-ghost btn-xs my-1"
+              aria-expanded={showAll}
+              onclick={() => {
+                showAll = !showAll;
+              }}
+            >
+              {showAll ? "Show fewer lines" : `⋯ ${card.output.hiddenCount} more lines`}
+            </button>
+            {#if !showAll}
+              <pre class="overflow-x-auto">{card.output.tail.join("\n")}</pre>
+            {/if}
+          {/if}
+        </div>
+      {/if}
+    </section>
+  </div>
+</LazyCollapse>