Add paged chat history loading

2026-05-07 15:46:08 +02:00
parent 5430a44561
commit eb59f1eb00
42 changed files with 1894 additions and 333 deletions
@@ -0,0 +1,47 @@
+import js from "@eslint/js";
+import { defineConfig } from "eslint/config";
+import globals from "globals";
+import tseslint from "typescript-eslint";
+
+export default defineConfig([
+  {
+    ignores: ["dist/**", "node_modules/**"],
+  },
+  {
+    files: ["src/**/*.ts", "vite.config.ts"],
+    extends: [
+      js.configs.recommended,
+      tseslint.configs.strictTypeChecked,
+      tseslint.configs.stylisticTypeChecked,
+    ],
+    languageOptions: {
+      globals: {
+        ...globals.browser,
+        ...globals.node,
+      },
+      parserOptions: {
+        project: "./tsconfig.json",
+        tsconfigRootDir: import.meta.dirname,
+      },
+    },
+    rules: {
+      "@typescript-eslint/no-explicit-any": "error",
+      "@typescript-eslint/no-unsafe-assignment": "error",
+      "@typescript-eslint/no-unsafe-member-access": "error",
+      "@typescript-eslint/no-unsafe-call": "error",
+      "@typescript-eslint/no-unsafe-return": "error",
+      "@typescript-eslint/no-unsafe-argument": "error",
+      "@typescript-eslint/no-non-null-assertion": "error",
+      "@typescript-eslint/no-unnecessary-condition": "error",
+      "@typescript-eslint/strict-boolean-expressions": "error",
+      "@typescript-eslint/switch-exhaustiveness-check": "error",
+      "@typescript-eslint/no-floating-promises": "error",
+      "@typescript-eslint/no-misused-promises": "error",
+      "@typescript-eslint/await-thenable": "error",
+      "@typescript-eslint/no-unnecessary-type-assertion": "error",
+      "@typescript-eslint/consistent-type-assertions": ["error", { assertionStyle: "never" }],
+      "@typescript-eslint/restrict-template-expressions": "error",
+      "@typescript-eslint/restrict-plus-operands": "error",
+    },
+  },
+]);
@@ -10,6 +10,8 @@
    "dev:server": "npm run dev:web",
    "dev:client": "vite --host 0.0.0.0",
    "build": "tsc && vite build",
+    "typecheck": "tsc --noEmit",
+    "lint": "eslint \"src/**/*.ts\" vite.config.ts",
    "start": "tsx src/server/index.ts",
    "start:sessiond": "tsx src/server/sessiond.ts"
  },
@@ -23,10 +25,14 @@
    "ws": "^8.18.3"
  },
  "devDependencies": {
+    "@eslint/js": "^10.0.1",
    "@types/node": "^24.10.1",
    "@types/ws": "^8.18.1",
+    "eslint": "^10.3.0",
+    "globals": "^17.6.0",
    "tsx": "^4.20.6",
    "typescript": "^5.9.3",
+    "typescript-eslint": "^8.59.2",
    "vite": "^7.2.4"
  }
 }
@@ -64,38 +64,49 @@ export interface CommandOption {
  description?: string;
 }

+export interface MessagePage {
+  messages: unknown[];
+  start: number;
+  total: number;
+}
+
 export type CommandResult =
  | { type: "done"; message?: string; session?: SessionInfo }
  | { type: "select"; requestId: string; title: string; options: CommandOption[] }
  | { type: "unsupported"; message: string };

-async function request<T>(url: string, init?: RequestInit): Promise<T> {
-  const response = await fetch(url, {
-    ...init,
-    headers: { "content-type": "application/json", ...init?.headers },
-  });
+async function request<T>(url: string, parse: (value: unknown) => T, init?: RequestInit): Promise<T> {
+  const headers = new Headers(init?.headers);
+  headers.set("content-type", "application/json");
+  const response = await fetch(url, { ...init, headers });
  if (!response.ok) {
-    const body = await response.json().catch(() => ({}));
-    throw new Error(body.error ?? response.statusText);
+    const body: unknown = await response.json().catch((): unknown => ({}));
+    throw new Error(errorMessage(body) ?? response.statusText);
  }
-  return response.json() as Promise<T>;
+  const body: unknown = await response.json();
+  return parse(body);
+}
+
+function errorMessage(value: unknown): string | undefined {
+  if (!isRecord(value)) return undefined;
+  return typeof value["error"] === "string" ? value["error"] : undefined;
 }

 export const api = {
-  projects: () => request<Project[]>("/api/projects"),
-  addProject: (path: string, name?: string) => request<Project>("/api/projects", { method: "POST", body: JSON.stringify({ path, name }) }),
-  workspaces: (projectId: string) => request<Workspace[]>(`/api/projects/${projectId}/workspaces`),
-  sessions: (cwd: string) => request<SessionInfo[]>(`/api/sessions?cwd=${encodeURIComponent(cwd)}`),
-  startSession: (cwd: string) => request<SessionInfo>("/api/sessions", { method: "POST", body: JSON.stringify({ cwd }) }),
-  messages: (sessionId: string) => request<any[]>(`/api/sessions/${sessionId}/messages`),
-  status: (sessionId: string) => request<SessionStatus>(`/api/sessions/${sessionId}/status`),
-  commands: (sessionId: string) => request<SlashCommand[]>(`/api/sessions/${sessionId}/commands`),
-  files: (cwd: string, query: string, kind?: FileSuggestion["kind"]) => request<FileSuggestion[]>(`/api/files?cwd=${encodeURIComponent(cwd)}&q=${encodeURIComponent(query)}${kind ? `&kind=${encodeURIComponent(kind)}` : ""}`),
-  prompt: (sessionId: string, text: string) => request<{ accepted: true }>(`/api/sessions/${sessionId}/prompt`, { method: "POST", body: JSON.stringify({ text }) }),
-  shell: (sessionId: string, text: string) => request<{ accepted: true }>(`/api/sessions/${sessionId}/shell`, { method: "POST", body: JSON.stringify({ text }) }),
-  runCommand: (sessionId: string, text: string) => request<CommandResult>(`/api/sessions/${sessionId}/commands/run`, { method: "POST", body: JSON.stringify({ text }) }),
-  respondToCommand: (sessionId: string, requestId: string, value: string) => request<CommandResult>(`/api/sessions/${sessionId}/commands/respond`, { method: "POST", body: JSON.stringify({ requestId, value }) }),
-  stop: (sessionId: string) => request<{ stopped: true }>(`/api/sessions/${sessionId}/stop`, { method: "POST" }),
+  projects: () => request("/api/projects", arrayOf(parseProject)),
+  addProject: (path: string, name?: string) => request("/api/projects", parseProject, { method: "POST", body: JSON.stringify({ path, name }) }),
+  workspaces: (projectId: string) => request(`/api/projects/${projectId}/workspaces`, arrayOf(parseWorkspace)),
+  sessions: (cwd: string) => request(`/api/sessions?cwd=${encodeURIComponent(cwd)}`, arrayOf(parseSessionInfo)),
+  startSession: (cwd: string) => request("/api/sessions", parseSessionInfo, { method: "POST", body: JSON.stringify({ cwd }) }),
+  messages: (sessionId: string, options?: { limit?: number; before?: number }) => request(messageUrl(sessionId, options), parseMessagePage),
+  status: (sessionId: string) => request(`/api/sessions/${sessionId}/status`, parseSessionStatus),
+  commands: (sessionId: string) => request(`/api/sessions/${sessionId}/commands`, arrayOf(parseSlashCommand)),
+  files: (cwd: string, query: string, kind?: FileSuggestion["kind"]) => request(`/api/files?cwd=${encodeURIComponent(cwd)}&q=${encodeURIComponent(query)}${kind !== undefined ? `&kind=${encodeURIComponent(kind)}` : ""}`, arrayOf(parseFileSuggestion)),
+  prompt: (sessionId: string, text: string) => request(`/api/sessions/${sessionId}/prompt`, parseAccepted, { method: "POST", body: JSON.stringify({ text }) }),
+  shell: (sessionId: string, text: string) => request(`/api/sessions/${sessionId}/shell`, parseAccepted, { method: "POST", body: JSON.stringify({ text }) }),
+  runCommand: (sessionId: string, text: string) => request(`/api/sessions/${sessionId}/commands/run`, parseCommandResult, { method: "POST", body: JSON.stringify({ text }) }),
+  respondToCommand: (sessionId: string, requestId: string, value: string) => request(`/api/sessions/${sessionId}/commands/respond`, parseCommandResult, { method: "POST", body: JSON.stringify({ requestId, value }) }),
+  stop: (sessionId: string) => request(`/api/sessions/${sessionId}/stop`, parseStopped, { method: "POST" }),
 };

 export function sessionEvents(sessionId: string): WebSocket {
@@ -106,7 +117,202 @@ export function globalSessionEvents(): WebSocket {
  return new WebSocket(`${webSocketBaseUrl()}/api/sessions/events`);
 }

+function messageUrl(sessionId: string, options?: { limit?: number; before?: number }): string {
+  const params = new URLSearchParams();
+  if (options?.limit !== undefined) params.set("limit", String(options.limit));
+  if (options?.before !== undefined) params.set("before", String(options.before));
+  const query = params.toString();
+  return `/api/sessions/${sessionId}/messages${query ? `?${query}` : ""}`;
+}
+
 function webSocketBaseUrl(): string {
  const protocol = location.protocol === "https:" ? "wss:" : "ws:";
  return `${protocol}//${location.host}`;
 }
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null;
+}
+
+function requireRecord(value: unknown): Record<string, unknown> {
+  if (!isRecord(value)) throw new Error("Expected object response");
+  return value;
+}
+
+function requireString(record: Record<string, unknown>, key: string): string {
+  const value = record[key];
+  if (typeof value !== "string") throw new Error(`Expected string field: ${key}`);
+  return value;
+}
+
+function optionalString(record: Record<string, unknown>, key: string): string | undefined {
+  const value = record[key];
+  if (value === undefined) return undefined;
+  if (typeof value !== "string") throw new Error(`Expected optional string field: ${key}`);
+  return value;
+}
+
+function requireNumber(record: Record<string, unknown>, key: string): number {
+  const value = record[key];
+  if (typeof value !== "number") throw new Error(`Expected number field: ${key}`);
+  return value;
+}
+
+function requireBoolean(record: Record<string, unknown>, key: string): boolean {
+  const value = record[key];
+  if (typeof value !== "boolean") throw new Error(`Expected boolean field: ${key}`);
+  return value;
+}
+
+function arrayOf<T>(parse: (value: unknown) => T): (value: unknown) => T[] {
+  return (value) => {
+    if (!Array.isArray(value)) throw new Error("Expected array response");
+    return value.map(parse);
+  };
+}
+
+function parseUnknownArray(value: unknown): unknown[] {
+  if (!Array.isArray(value)) throw new Error("Expected array response");
+  return value;
+}
+
+function parseMessagePage(value: unknown): MessagePage {
+  if (Array.isArray(value)) return { messages: value, start: 0, total: value.length };
+  const record = requireRecord(value);
+  return { messages: parseUnknownArray(record["messages"]), start: requireNumber(record, "start"), total: requireNumber(record, "total") };
+}
+
+function parseProject(value: unknown): Project {
+  const record = requireRecord(value);
+  return { id: requireString(record, "id"), name: requireString(record, "name"), path: requireString(record, "path"), createdAt: requireString(record, "createdAt") };
+}
+
+function parseWorkspace(value: unknown): Workspace {
+  const record = requireRecord(value);
+  const branch = optionalString(record, "branch");
+  return {
+    id: requireString(record, "id"),
+    projectId: requireString(record, "projectId"),
+    path: requireString(record, "path"),
+    label: requireString(record, "label"),
+    ...(branch === undefined ? {} : { branch }),
+    isMain: requireBoolean(record, "isMain"),
+    isGitWorktree: requireBoolean(record, "isGitWorktree"),
+  };
+}
+
+function parseSessionInfo(value: unknown): SessionInfo {
+  const record = requireRecord(value);
+  const name = optionalString(record, "name");
+  return {
+    id: requireString(record, "id"),
+    path: requireString(record, "path"),
+    cwd: requireString(record, "cwd"),
+    ...(name === undefined ? {} : { name }),
+    created: requireString(record, "created"),
+    modified: requireString(record, "modified"),
+    messageCount: requireNumber(record, "messageCount"),
+    firstMessage: requireString(record, "firstMessage"),
+  };
+}
+
+function parseSessionStatus(value: unknown): SessionStatus {
+  const record = requireRecord(value);
+  return {
+    sessionId: requireString(record, "sessionId"),
+    isStreaming: requireBoolean(record, "isStreaming"),
+    isCompacting: requireBoolean(record, "isCompacting"),
+    isBashRunning: requireBoolean(record, "isBashRunning"),
+    pendingMessageCount: requireNumber(record, "pendingMessageCount"),
+    tokens: parseTokens(record["tokens"]),
+    cost: requireNumber(record, "cost"),
+    ...optionalModel(record["model"]),
+    ...optionalContextUsage(record["contextUsage"]),
+    ...optionalField("thinkingLevel", optionalString(record, "thinkingLevel")),
+  };
+}
+
+function parseTokens(value: unknown): SessionStatus["tokens"] {
+  const record = requireRecord(value);
+  return {
+    input: requireNumber(record, "input"),
+    output: requireNumber(record, "output"),
+    cacheRead: requireNumber(record, "cacheRead"),
+    cacheWrite: requireNumber(record, "cacheWrite"),
+    total: requireNumber(record, "total"),
+  };
+}
+
+function optionalModel(value: unknown): Pick<SessionStatus, "model"> | object {
+  if (value === undefined) return {};
+  const record = requireRecord(value);
+  return { model: { ...optionalField("provider", optionalString(record, "provider")), ...optionalField("id", optionalString(record, "id")), ...optionalField("name", optionalString(record, "name")), ...optionalField("contextWindow", optionalNumber(record, "contextWindow")), ...optionalField("reasoning", record["reasoning"]) } };
+}
+
+function optionalContextUsage(value: unknown): Pick<SessionStatus, "contextUsage"> | object {
+  if (value === undefined) return {};
+  const record = requireRecord(value);
+  return { contextUsage: { tokens: numberOrNull(record, "tokens"), contextWindow: requireNumber(record, "contextWindow"), percent: numberOrNull(record, "percent") } };
+}
+
+function parseSlashCommand(value: unknown): SlashCommand {
+  const record = requireRecord(value);
+  const source = requireString(record, "source");
+  if (source !== "extension" && source !== "prompt" && source !== "skill" && source !== "builtin") throw new Error("Invalid command source");
+  return { name: requireString(record, "name"), source, ...optionalField("description", optionalString(record, "description")) };
+}
+
+function parseFileSuggestion(value: unknown): FileSuggestion {
+  const record = requireRecord(value);
+  const kind = requireString(record, "kind");
+  if (kind !== "tracked" && kind !== "untracked" && kind !== "other") throw new Error("Invalid file kind");
+  return { path: requireString(record, "path"), kind };
+}
+
+function parseCommandResult(value: unknown): CommandResult {
+  const record = requireRecord(value);
+  const type = requireString(record, "type");
+  if (type === "unsupported") return { type, message: requireString(record, "message") };
+  if (type === "select") return { type, requestId: requireString(record, "requestId"), title: requireString(record, "title"), options: arrayOf(parseCommandOption)(record["options"]) };
+  if (type === "done") return { type, ...optionalField("message", optionalString(record, "message")), ...optionalSession(record["session"]) };
+  throw new Error("Invalid command result type");
+}
+
+function parseCommandOption(value: unknown): CommandOption {
+  const record = requireRecord(value);
+  return { value: requireString(record, "value"), label: requireString(record, "label"), ...optionalField("description", optionalString(record, "description")) };
+}
+
+function optionalSession(value: unknown): Pick<Extract<CommandResult, { type: "done" }>, "session"> | object {
+  return value === undefined ? {} : { session: parseSessionInfo(value) };
+}
+
+function parseAccepted(value: unknown): { accepted: true } {
+  const record = requireRecord(value);
+  if (record["accepted"] !== true) throw new Error("Expected accepted response");
+  return { accepted: true };
+}
+
+function parseStopped(value: unknown): { stopped: true } {
+  const record = requireRecord(value);
+  if (record["stopped"] !== true) throw new Error("Expected stopped response");
+  return { stopped: true };
+}
+
+function optionalNumber(record: Record<string, unknown>, key: string): number | undefined {
+  const value = record[key];
+  if (value === undefined) return undefined;
+  if (typeof value !== "number") throw new Error(`Expected optional number field: ${key}`);
+  return value;
+}
+
+function numberOrNull(record: Record<string, unknown>, key: string): number | null {
+  const value = record[key];
+  if (value === null) return null;
+  if (typeof value !== "number") throw new Error(`Expected number|null field: ${key}`);
+  return value;
+}
+
+function optionalField(key: string, value: unknown): object {
+  return value === undefined ? {} : { [key]: value };
+}
@@ -6,14 +6,17 @@ export interface AppState {
  workspaces: Workspace[];
  sessions: SessionInfo[];
  messages: ChatLine[];
-  selectedProject?: Project;
-  selectedWorkspace?: Workspace;
-  selectedSession?: SessionInfo;
-  status?: SessionStatus;
-  activity?: SessionActivity;
+  messagePageStart: number;
+  messagePageTotal: number;
+  isLoadingEarlierMessages: boolean;
+  selectedProject: Project | undefined;
+  selectedWorkspace: Workspace | undefined;
+  selectedSession: SessionInfo | undefined;
+  status: SessionStatus | undefined;
+  activity: SessionActivity | undefined;
  sessionStatuses: Record<string, SessionStatus>;
  sessionActivities: Record<string, SessionActivity>;
-  commandDialog?: Extract<CommandResult, { type: "select" }>;
+  commandDialog: Extract<CommandResult, { type: "select" }> | undefined;
  error: string;
 }

@@ -23,8 +26,17 @@ export function initialAppState(): AppState {
    workspaces: [],
    sessions: [],
    messages: [],
+    messagePageStart: 0,
+    messagePageTotal: 0,
+    isLoadingEarlierMessages: false,
+    selectedProject: undefined,
+    selectedWorkspace: undefined,
+    selectedSession: undefined,
+    status: undefined,
+    activity: undefined,
    sessionStatuses: {},
    sessionActivities: {},
+    commandDialog: undefined,
    error: "",
  };
 }
@@ -4,7 +4,7 @@ export type ChatGroup =
  | { kind: "message"; message: ChatLine; index: number }
  | { kind: "group"; messages: ChatLine[]; startIndex: number };

-export function groupChatMessages(messages: ChatLine[]): ChatGroup[] {
+export function groupChatMessages(messages: ChatLine[], indexOffset = 0): ChatGroup[] {
  const groups: ChatGroup[] = [];
  let eventMessages: ChatLine[] = [];
  let eventStartIndex = 0;
@@ -23,10 +23,11 @@ export function groupChatMessages(messages: ChatLine[]): ChatGroup[] {
    const readableParts = message.parts.filter((part) => isReadablePart(message, part));
    const technicalParts = message.parts.filter((part) => !isReadablePart(message, part));

-    if (technicalParts.length) pushEvent({ role: message.role, parts: technicalParts }, index);
+    const absoluteIndex = indexOffset + index;
+    if (technicalParts.length) pushEvent({ role: message.role, parts: technicalParts }, absoluteIndex);
    if (readableParts.length) {
      flushEvents();
-      groups.push({ kind: "message", message: { role: message.role, parts: readableParts }, index });
+      groups.push({ kind: "message", message: { role: message.role, parts: readableParts }, index: absoluteIndex });
    }
  });
  flushEvents();
@@ -38,8 +39,8 @@ export function summarizeChatGroup(messages: ChatLine[]): string {
    acc[message.role] = (acc[message.role] ?? 0) + 1;
    return acc;
  }, {});
-  const details = Object.entries(counts).map(([role, count]) => `${count} ${role}`).join(" · ");
-  return `${messages.length} ${messages.length === 1 ? "event" : "events"}${details ? ` · ${details}` : ""}`;
+  const details = Object.entries(counts).map(([role, count]) => `${String(count)} ${role}`).join(" · ");
+  return `${String(messages.length)} ${messages.length === 1 ? "event" : "events"}${details !== "" ? ` · ${details}` : ""}`;
 }

 function isReadablePart(message: ChatLine, part: ChatPart): boolean {
@@ -1,6 +1,6 @@
 import type { ChatLine, ChatPart } from "./components/shared";

-export function normalizeMessages(messages: any[]): ChatLine[] {
+export function normalizeMessages(messages: unknown[]): ChatLine[] {
  return messages.flatMap(normalizeMessage).filter((message) => message.parts.length > 0);
 }

@@ -20,23 +20,27 @@ export function appendText(messages: ChatLine[], role: ChatLine["role"], text: s
  return [...messages, textMessage(role, text)];
 }

-function normalizeMessage(message: any): ChatLine[] {
-  if (message?.role === "bashExecution") return [normalizeBashExecution(message)];
-  const role = normalizeRole(message?.role);
-  const parts = normalizeContent(message?.content, message);
+function normalizeMessage(message: unknown): ChatLine[] {
+  if (getString(message, "role") === "bashExecution") return [normalizeBashExecution(message)];
+  const role = normalizeRole(getString(message, "role"));
+  const parts = normalizeContent(getProperty(message, "content"), message);
  if (role === "tool") return [{ role, parts }];

  const visible = parts.filter((part) => part.type !== "empty");
-  return visible.length ? [{ role, parts: visible }] : [];
+  return visible.length > 0 ? [{ role, parts: visible }] : [];
 }

-function normalizeBashExecution(message: any): ChatLine {
-  const lines = message.excludeFromContext ? ["excluded from context", "", `$ ${message.command ?? ""}`] : [`$ ${message.command ?? ""}`];
-  if (message.output) lines.push("", String(message.output));
-  if (message.exitCode != null) lines.push("", `exit ${message.exitCode}`);
-  if (message.cancelled) lines.push("", "cancelled");
-  if (message.truncated) lines.push("", "output truncated");
-  if (message.fullOutputPath) lines.push("", `full output: ${message.fullOutputPath}`);
+function normalizeBashExecution(message: unknown): ChatLine {
+  const command = getString(message, "command") ?? "";
+  const lines = getBoolean(message, "excludeFromContext") === true ? ["excluded from context", "", `$ ${command}`] : [`$ ${command}`];
+  const output = getProperty(message, "output");
+  if (output != null) lines.push("", stringifyPrimitive(output));
+  const exitCode = getProperty(message, "exitCode");
+  if (exitCode != null) lines.push("", `exit ${stringifyPrimitive(exitCode)}`);
+  if (getBoolean(message, "cancelled") === true) lines.push("", "cancelled");
+  if (getBoolean(message, "truncated") === true) lines.push("", "output truncated");
+  const fullOutputPath = getString(message, "fullOutputPath");
+  if (fullOutputPath !== undefined && fullOutputPath !== "") lines.push("", `full output: ${fullOutputPath}`);
  return { role: "bash", parts: [{ type: "text", text: lines.join("\n") }] };
 }

@@ -47,33 +51,41 @@ function normalizeRole(role: unknown): ChatLine["role"] {
  return "system";
 }

-function normalizeContent(content: unknown, message: any): ChatPart[] {
-  if (typeof content === "string") return content ? [{ type: "text", text: content }] : [];
+function normalizeContent(content: unknown, message: unknown): ChatPart[] {
+  if (typeof content === "string") return content !== "" ? [{ type: "text", text: content }] : [];
  if (!Array.isArray(content)) return objectFallback(content);

-  return content.flatMap((part: any): ChatPart[] => {
-    if (part?.type === "text") return part.text ? [{ type: "text", text: part.text }] : [];
-    if (part?.type === "thinking") return part.thinking || part.text ? [{ type: "thinking", text: part.thinking ?? part.text }] : [];
-    if (part?.type === "toolCall") return [{ type: "toolCall", toolName: part.name ?? "tool", summary: summarizeArgs(part.arguments) }];
-    if (part?.type === "image") return [{ type: "text", text: "[image]" }];
+  return content.flatMap((part): ChatPart[] => {
+    const type = getString(part, "type");
+    const text = getString(part, "text");
+    if (type === "text") return text !== undefined && text !== "" ? [{ type: "text", text }] : [];
+    if (type === "thinking") {
+      const thinking = getString(part, "thinking") ?? text;
+      return thinking !== undefined && thinking !== "" ? [{ type: "thinking", text: thinking }] : [];
+    }
+    if (type === "toolCall") return [{ type: "toolCall", toolName: getString(part, "name") ?? "tool", summary: summarizeArgs(getProperty(part, "arguments")) }];
+    if (type === "image") return [{ type: "text", text: "[image]" }];
    return objectFallback(part);
-  }).map((part) => part.type === "text" && message?.role === "toolResult"
-    ? { type: "toolResult", toolName: message.toolName ?? "tool", text: part.text, isError: !!message.isError }
+  }).map((part) => part.type === "text" && getString(message, "role") === "toolResult"
+    ? { type: "toolResult", toolName: getString(message, "toolName") ?? "tool", text: part.text, isError: getBoolean(message, "isError") === true }
    : part);
 }

 function objectFallback(value: unknown): ChatPart[] {
  if (value == null) return [];
  if (typeof value === "object") return [{ type: "text", text: summarizeArgs(value) }];
-  return [{ type: "text", text: String(value) }];
+  return [{ type: "text", text: stringifyPrimitive(value) }];
 }

-function summarizeArgs(args: any): string {
-  if (!args || typeof args !== "object") return args == null ? "" : String(args);
-  if (typeof args.command === "string") return args.command;
-  if (typeof args.path === "string") return args.path;
-  if (typeof args.oldText === "string" && typeof args.newText === "string") return "edit text replacement";
-  if (Array.isArray(args.edits)) return `${args.edits.length} edit${args.edits.length === 1 ? "" : "s"}`;
+function summarizeArgs(args: unknown): string {
+  if (!isRecord(args)) return stringifyPrimitive(args);
+  const command = getString(args, "command");
+  if (command !== undefined) return command;
+  const path = getString(args, "path");
+  if (path !== undefined) return path;
+  if (typeof args["oldText"] === "string" && typeof args["newText"] === "string") return "edit text replacement";
+  const edits = args["edits"];
+  if (Array.isArray(edits)) return `${String(edits.length)} edit${edits.length === 1 ? "" : "s"}`;
  const entries = Object.entries(args).filter(([, value]) => value != null).slice(0, 3);
  return entries.map(([key, value]) => `${key}: ${shortValue(value)}`).join(" · ");
 }
@@ -81,7 +93,32 @@ function summarizeArgs(args: any): string {
 function shortValue(value: unknown): string {
  if (typeof value === "string") return value.length > 80 ? `${value.slice(0, 77)}…` : value;
  if (typeof value === "number" || typeof value === "boolean") return String(value);
-  if (Array.isArray(value)) return `${value.length} item${value.length === 1 ? "" : "s"}`;
-  if (typeof value === "object" && value) return "object";
+  if (Array.isArray(value)) return `${String(value.length)} item${value.length === 1 ? "" : "s"}`;
+  if (typeof value === "object" && value !== null) return "object";
+  return "";
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null;
+}
+
+function getProperty(value: unknown, key: string): unknown {
+  return isRecord(value) ? value[key] : undefined;
+}
+
+function getString(value: unknown, key: string): string | undefined {
+  const property = getProperty(value, key);
+  return typeof property === "string" ? property : undefined;
+}
+
+function getBoolean(value: unknown, key: string): boolean | undefined {
+  const property = getProperty(value, key);
+  return typeof property === "boolean" ? property : undefined;
+}
+
+function stringifyPrimitive(value: unknown): string {
+  if (value == null) return "";
+  if (typeof value === "string") return value;
+  if (typeof value === "number" || typeof value === "boolean" || typeof value === "bigint") return String(value);
  return "";
 }
@@ -8,7 +8,7 @@ export class AutocompleteMenu extends LitElement {
  @property({ type: Number }) selectedIndex = 0;
  @property({ attribute: false }) onPick?: (item: CompletionItem) => void;

-  render() {
+  override render() {
    if (!this.items.length) return null;
    return html`
      <div class="menu">
@@ -16,12 +16,12 @@ export class AutocompleteMenu extends LitElement {
          <button class=${index === this.selectedIndex ? "selected" : ""} @mousedown=${(event: MouseEvent) => { event.preventDefault(); this.onPick?.(item); }}>
            <strong>${item.insertText}</strong>
            <span>${item.detail}</span>
-            ${item.description ? html`<small>${item.description}</small>` : null}
+            ${item.description !== undefined && item.description !== "" ? html`<small>${item.description}</small>` : null}
          </button>
        `)}
      </div>
    `;
  }

-  static styles = autocompleteStyles;
+  static override styles = autocompleteStyles;
 }
@@ -5,41 +5,92 @@ import type { ChatLine, ChatPart } from "./shared";
 import { chatStyles } from "./shared";
 import "./FormattedText";

+function isScrollPosition(value: unknown): value is { index: number; offset: number } {
+  return typeof value === "object"
+    && value !== null
+    && "index" in value
+    && "offset" in value
+    && typeof value.index === "number"
+    && typeof value.offset === "number";
+}
+
@customElement("chat-view")
 export class ChatView extends LitElement {
  @property({ attribute: false }) messages: ChatLine[] = [];
  @property() sessionId = "";
+  @property({ type: Number }) messageStart = 0;
+  @property({ type: Number }) messageTotal = 0;
+  @property({ type: Boolean }) hasMore = false;
+  @property({ type: Boolean }) loadingMore = false;
+  @property({ attribute: false }) onLoadMore?: () => void;
  @query(".chat") private chat?: HTMLDivElement;
  @state() private pinnedToBottom = true;
  @state() private openGroupKeys = new Set<string>();
+  @state() private loadedScrollPercent = 100;
  private suppressScrollSave = false;
  private saveScrollTimer?: number;

-  disconnectedCallback(): void {
+  override disconnectedCallback(): void {
    window.clearTimeout(this.saveScrollTimer);
    super.disconnectedCallback();
  }

-  protected willUpdate(changed: Map<string, unknown>): void {
+  protected override willUpdate(changed: Map<string, unknown>): void {
    if (changed.has("sessionId")) this.openGroupKeys = this.readOpenGroupKeys();
    this.pinnedToBottom = this.isNearBottom();
  }

-  protected updated(changed: Map<string, unknown>): void {
+  protected override updated(changed: Map<string, unknown>): void {
    if (changed.has("sessionId")) return;
    if (changed.has("messages") && this.pinnedToBottom) this.scrollToBottom();
+    this.updateLoadedScrollPercent();
  }

-  render() {
+  override render() {
    return html`
-      <div class="chat" @scroll=${this.onScroll}>
-        ${groupChatMessages(this.messages).map((group) => group.kind === "message"
-          ? this.renderMessage(group.message, group.index)
-          : this.renderMessageGroup(group.messages, group.startIndex))}
+      <div class="chat-wrap">
+        ${this.renderHistoryIndicator()}
+        <div class="chat" @scroll=${() => { this.onScroll(); }}>
+          ${this.renderHistoryBoundary()}
+          ${groupChatMessages(this.messages, this.messageStart).map((group) => group.kind === "message"
+            ? this.renderMessage(group.message, group.index)
+            : this.renderMessageGroup(group.messages, group.startIndex))}
+        </div>
      </div>
    `;
  }

+  private renderHistoryIndicator() {
+    if (!this.messages.length || this.messageTotal <= 0) return null;
+    const loadedCount = this.messages.length;
+    const loadedPercent = Math.min(100, Math.round((loadedCount / this.messageTotal) * 100));
+    const olderCount = this.messageStart;
+    const fullHistory = olderCount <= 0
+      ? "full history loaded"
+      : `${olderCount} older not loaded · ${loadedPercent}% loaded`;
+    return html`
+      <div class="history-indicator">
+        <div>${fullHistory}</div>
+        <div>loaded scroll: ${this.loadedScrollPercent}% from top</div>
+      </div>
+    `;
+  }
+
+  private renderHistoryBoundary() {
+    const range = this.historyRangeLabel();
+    if (this.loadingMore) return html`<div class="history-boundary"><span>Loading earlier messages…</span>${range}</div>`;
+    if (this.hasMore) return html`<div class="history-boundary"><span>Scroll up to load earlier messages</span>${range}</div>`;
+    if (this.messages.length) return html`<div class="history-boundary"><span>Beginning of session</span>${range}</div>`;
+    return null;
+  }
+
+  private historyRangeLabel() {
+    if (!this.messages.length || this.messageTotal <= 0) return null;
+    const from = this.messageStart + 1;
+    const to = this.messageStart + this.messages.length;
+    return html`<small>Showing messages ${from}–${to} of ${this.messageTotal}</small>`;
+  }
+
  private renderMessage(message: ChatLine, index: number) {
    return html`
      <article class="msg ${message.role}" data-index=${index}>
@@ -52,7 +103,7 @@ export class ChatView extends LitElement {
  private renderMessageGroup(messages: ChatLine[], startIndex: number) {
    const key = this.groupKey(startIndex);
    return html`
-      <details class="msg event-group" data-index=${startIndex} ?open=${this.openGroupKeys.has(key)} @toggle=${(event: Event) => this.onGroupToggle(key, event)}>
+      <details class="msg event-group" data-index=${startIndex} ?open=${this.openGroupKeys.has(key)} @toggle=${(event: Event) => { this.onGroupToggle(key, event); }}>
        <summary>
          <b class="label">events</b>
          <span>${summarizeChatGroup(messages)}</span>
@@ -84,7 +135,8 @@ export class ChatView extends LitElement {
  }

  private onGroupToggle(key: string, event: Event) {
-    const details = event.currentTarget as HTMLDetailsElement;
+    const details = event.currentTarget;
+    if (!(details instanceof HTMLDetailsElement)) return;
    const openGroupKeys = new Set(this.openGroupKeys);
    if (details.open) openGroupKeys.add(key);
    else openGroupKeys.delete(key);
@@ -93,10 +145,20 @@ export class ChatView extends LitElement {
  }

  private onScroll() {
+    this.updateLoadedScrollPercent();
+    if (this.chat && this.chat.scrollTop < 64 && this.hasMore && !this.loadingMore) this.onLoadMore?.();
    this.pinnedToBottom = this.isNearBottom();
    if (!this.suppressScrollSave) this.scheduleScrollPositionSave();
  }

+  private updateLoadedScrollPercent(): void {
+    const chat = this.chat;
+    if (!chat) return;
+    const maxScroll = chat.scrollHeight - chat.clientHeight;
+    const percent = maxScroll <= 0 ? 100 : Math.round((chat.scrollTop / maxScroll) * 100);
+    this.loadedScrollPercent = Math.max(0, Math.min(100, percent));
+  }
+
  private isNearBottom(): boolean {
    const chat = this.chat;
    if (!chat) return true;
@@ -154,7 +216,7 @@ export class ChatView extends LitElement {
      }
      const chatTop = chat.getBoundingClientRect().top;
      const position = {
-        index: Number(firstVisible.dataset.index ?? 0),
+        index: Number(firstVisible.dataset["index"] ?? 0),
        offset: firstVisible.getBoundingClientRect().top - chatTop,
      };
      localStorage.setItem(this.storageKey(sessionId), JSON.stringify(position));
@@ -165,17 +227,17 @@ export class ChatView extends LitElement {

  private scheduleScrollPositionSave() {
    window.clearTimeout(this.saveScrollTimer);
-    this.saveScrollTimer = window.setTimeout(() => this.saveScrollPosition(), 180);
+    this.saveScrollTimer = window.setTimeout(() => { this.saveScrollPosition(); }, 180);
  }

  private readStoredScrollPosition(): { index: number; offset: number } | undefined {
-    if (!this.sessionId) return undefined;
+    if (this.sessionId === "") return undefined;
    try {
      const raw = localStorage.getItem(this.storageKey());
-      if (!raw) return undefined;
-      const value = JSON.parse(raw);
-      if (typeof value?.index !== "number" || typeof value?.offset !== "number") return undefined;
-      return { index: value.index, offset: value.offset };
+      if (raw === null || raw === "") return undefined;
+      const value: unknown = JSON.parse(raw);
+      if (!isScrollPosition(value)) return undefined;
+      return value;
    } catch {
      return undefined;
    }
@@ -192,7 +254,7 @@ export class ChatView extends LitElement {
  }

  private articleAt(index: number): HTMLElement | undefined {
-    return this.articles().find((article) => Number(article.dataset.index) === index);
+    return this.articles().find((article) => Number(article.dataset["index"]) === index);
  }

  private articles(): HTMLElement[] {
@@ -218,14 +280,14 @@ export class ChatView extends LitElement {
  }

  private groupKey(startIndex: number): string {
-    return `${this.sessionId}:${startIndex}`;
+    return `${this.sessionId}:${String(startIndex)}`;
  }

  private readOpenGroupKeys(): Set<string> {
-    if (!this.sessionId) return new Set();
+    if (this.sessionId === "") return new Set();
    try {
      const raw = localStorage.getItem(this.groupStorageKey());
-      const value = raw ? JSON.parse(raw) : [];
+      const value: unknown = raw !== null && raw !== "" ? JSON.parse(raw) : [];
      return new Set(Array.isArray(value) ? value.filter((item) => typeof item === "string") : []);
    } catch {
      return new Set();
@@ -233,7 +295,7 @@ export class ChatView extends LitElement {
  }

  private saveOpenGroupKeys(): void {
-    if (!this.sessionId) return;
+    if (this.sessionId === "") return;
    try {
      localStorage.setItem(this.groupStorageKey(), JSON.stringify([...this.openGroupKeys]));
    } catch {
@@ -241,5 +303,5 @@ export class ChatView extends LitElement {
    }
  }

-  static styles = chatStyles;
+  static override styles = chatStyles;
 }
@@ -5,25 +5,25 @@ import { commandPickerStyles } from "./shared";

@customElement("command-picker")
 export class CommandPicker extends LitElement {
-  @property() title = "Select";
+  @property() override title = "Select";
  @property({ attribute: false }) options: CommandOption[] = [];
  @property({ attribute: false }) onPick?: (value: string) => void;
  @property({ attribute: false }) onCancel?: () => void;
  @state() private selectedIndex = 0;

-  render() {
+  override render() {
    return html`
      <div class="backdrop" @mousedown=${() => this.onCancel?.()}>
-        <section @mousedown=${(event: MouseEvent) => event.stopPropagation()}>
+        <section @mousedown=${(event: MouseEvent) => { event.stopPropagation(); }}>
          <header>
            <strong>${this.title}</strong>
            <button @click=${() => this.onCancel?.()}>×</button>
          </header>
-          <div class="options" @keydown=${(event: KeyboardEvent) => this.handleKeyDown(event)} tabindex="0">
+          <div class="options" @keydown=${(event: KeyboardEvent) => { this.handleKeyDown(event); }} tabindex="0">
            ${this.options.map((option, index) => html`
              <button class=${index === this.selectedIndex ? "selected" : ""} @click=${() => this.onPick?.(option.value)}>
                <span>${option.label}</span>
-                ${option.description ? html`<small>${option.description}</small>` : null}
+                ${option.description !== undefined && option.description !== "" ? html`<small>${option.description}</small>` : null}
              </button>
            `)}
          </div>
@@ -32,7 +32,7 @@ export class CommandPicker extends LitElement {
    `;
  }

-  firstUpdated() {
+  override firstUpdated() {
    this.renderRoot.querySelector<HTMLElement>(".options")?.focus();
  }

@@ -53,5 +53,5 @@ export class CommandPicker extends LitElement {
    }
  }

-  static styles = commandPickerStyles;
+  static override styles = commandPickerStyles;
 }
@@ -9,13 +9,15 @@ export class Composer extends LitElement {
  @property({ attribute: false }) onStopSession?: () => void;
  @state() private draft = "";

-  render() {
+  override render() {
    return html`
      <footer>
        <textarea
          .value=${this.draft}
          ?disabled=${this.disabled}
-          @input=${(e: Event) => (this.draft = (e.target as HTMLTextAreaElement).value)}
+          @input=${(event: Event) => {
+            if (event.target instanceof HTMLTextAreaElement) this.draft = event.target.value;
+          }}
          @keydown=${(e: KeyboardEvent) => {
            if (e.key === "Enter" && !e.shiftKey) {
              e.preventDefault();
@@ -24,7 +26,7 @@ export class Composer extends LitElement {
          }}
          placeholder="Message pi..."
        ></textarea>
-        <button ?disabled=${this.disabled} @click=${this.send}>Send</button>
+        <button ?disabled=${this.disabled} @click=${() => { this.send(); }}>Send</button>
        <button ?disabled=${this.disabled} @click=${() => this.onStopSession?.()}>Stop session</button>
      </footer>
    `;
@@ -32,10 +34,10 @@ export class Composer extends LitElement {

  private send() {
    const text = this.draft.trim();
-    if (!text || this.disabled) return;
+    if (text === "" || this.disabled) return;
    this.draft = "";
    this.onSend?.(text);
  }

-  static styles = composerStyles;
+  static override styles = composerStyles;
 }
@@ -8,9 +8,9 @@ import { formattedTextStyles } from "./shared";
 export class FormattedText extends LitElement {
  @property() text = "";

-  render() {
+  override render() {
    return html`<div class="formatted">${unsafeHTML(toSafeMarkdownHtml(this.text))}</div>`;
  }

-  static styles = formattedTextStyles;
+  static override styles = formattedTextStyles;
 }
@@ -25,30 +25,30 @@ export class PiWebApp extends LitElement {

  private readonly sessions = new SessionController(
    () => this.state,
-    (patch) => this.setState(patch),
-    () => this.updateUrl(),
+    (patch) => { this.setState(patch); },
+    () => { this.updateUrl(); },
  );
  private readonly workspaces = new WorkspaceController(
    () => this.state,
-    (patch) => this.setState(patch),
-    () => this.updateUrl(),
+    (patch) => { this.setState(patch); },
+    () => { this.updateUrl(); },
    this.sessions,
  );
  private readonly projects = new ProjectController(
    () => this.state,
-    (patch) => this.setState(patch),
+    (patch) => { this.setState(patch); },
    this.workspaces,
  );
  private readonly onPopState = () => void this.withChatScrollTransition(() => this.restoreRoute(false));

-  connectedCallback(): void {
+  override connectedCallback(): void {
    super.connectedCallback();
    window.addEventListener("popstate", this.onPopState);
    this.sessions.connectStatusUpdates();
    void this.loadProjectsAndRestoreRoute();
  }

-  disconnectedCallback(): void {
+  override disconnectedCallback(): void {
    window.removeEventListener("popstate", this.onPopState);
    this.sessions.dispose();
    super.disconnectedCallback();
@@ -65,7 +65,7 @@ export class PiWebApp extends LitElement {

  private async restoreRoute(updateUrl: boolean) {
    const route = readRoute();
-    if (!route.projectId) return;
+    if (route.projectId === undefined || route.projectId === "") return;
    const project = this.state.projects.find((p) => p.id === route.projectId);
    if (!project) return;
    await this.workspaces.selectProject(project, { workspaceId: route.workspaceId, sessionId: route.sessionId, updateUrl });
@@ -89,7 +89,7 @@ export class PiWebApp extends LitElement {
    });
  }

-  render() {
+  override render() {
    const state = this.state;
    return html`
      <div class="shell">
@@ -106,18 +106,18 @@ export class PiWebApp extends LitElement {
          ${state.error ? html`<div class="error">${state.error}</div>` : null}
          ${state.selectedSession ? html`
            <status-bar .status=${state.status} .activity=${state.activity} .workspace=${state.selectedWorkspace}></status-bar>
-            <chat-view .sessionId=${state.selectedSession.id} .messages=${state.messages}></chat-view>
+            <chat-view .sessionId=${state.selectedSession.id} .messages=${state.messages} .messageStart=${state.messagePageStart} .messageTotal=${state.messagePageTotal} .hasMore=${state.messagePageStart > 0} .loadingMore=${state.isLoadingEarlierMessages} .onLoadMore=${() => this.withChatScrollTransition(() => this.sessions.loadEarlierMessages())}></chat-view>
            <prompt-editor .sessionId=${state.selectedSession.id} .cwd=${state.selectedWorkspace?.path} .onSend=${(text: string) => this.sessions.send(text)} .onStopSession=${() => this.sessions.stopSession()}></prompt-editor>
-            ${state.commandDialog ? html`<command-picker .title=${state.commandDialog.title} .options=${state.commandDialog.options} .onPick=${(value: string) => this.sessions.respondToCommand(state.commandDialog!.requestId, value)} .onCancel=${() => this.sessions.cancelCommand()}></command-picker>` : null}
+            ${state.commandDialog !== undefined ? html`<command-picker .title=${state.commandDialog.title} .options=${state.commandDialog.options} .onPick=${(value: string) => this.sessions.respondToCommand(state.commandDialog?.requestId ?? "", value)} .onCancel=${() => { this.sessions.cancelCommand(); }}></command-picker>` : null}
          ` : html`<div class="empty">Select or start a session.</div>`}
        </main>
      </div>
    `;
  }

-  static styles = appStyles;
+  static override styles = appStyles;
 }

 function nextFrame(): Promise<void> {
-  return new Promise((resolve) => requestAnimationFrame(() => resolve()));
+  return new Promise((resolve) => requestAnimationFrame(() => { resolve(); }));
 }
@@ -9,7 +9,7 @@ export class ProjectList extends LitElement {
  @property({ attribute: false }) selected?: Project;
  @property({ attribute: false }) onSelect?: (project: Project) => void;

-  render() {
+  override render() {
    return html`
      <section>
        <h2>Projects</h2>
@@ -22,5 +22,5 @@ export class ProjectList extends LitElement {
    `;
  }

-  static styles = listStyles;
+  static override styles = listStyles;
 }
@@ -18,20 +18,20 @@ export class PromptEditor extends LitElement {
  @state() private selectedIndex = 0;
  private requestVersion = 0;

-  protected willUpdate(changed: PropertyValues<this>) {
+  protected override willUpdate(changed: PropertyValues<this>) {
    if (!changed.has("sessionId")) return;
-    const previousSessionId = changed.get("sessionId") as string | undefined;
-    if (previousSessionId) saveDraft(previousSessionId, this.draft);
-    this.draft = this.sessionId ? loadDraft(this.sessionId) : "";
+    const previousSessionId = changed.get("sessionId");
+    if (previousSessionId !== undefined && previousSessionId !== "") saveDraft(previousSessionId, this.draft);
+    this.draft = this.sessionId !== undefined && this.sessionId !== "" ? loadDraft(this.sessionId) : "";
    this.completions = [];
    this.selectedIndex = 0;
  }

-  protected updated(changed: PropertyValues) {
+  protected override updated(changed: PropertyValues) {
    if (changed.has("draft") || changed.has("sessionId")) this.resizeTextarea();
  }

-  render() {
+  override render() {
    const inputMode = inputModeForDraft(this.draft);
    const shellMode = inputMode.kind === "shell";
    return html`
@@ -40,14 +40,16 @@ export class PromptEditor extends LitElement {
          <textarea
            .value=${this.draft}
            ?disabled=${this.disabled}
-            @input=${(event: Event) => this.updateDraft((event.target as HTMLTextAreaElement).value)}
-            @keydown=${(event: KeyboardEvent) => this.handleKeyDown(event)}
+            @input=${(event: Event) => {
+              if (event.target instanceof HTMLTextAreaElement) this.updateDraft(event.target.value);
+            }}
+            @keydown=${(event: KeyboardEvent) => { this.handleKeyDown(event); }}
            placeholder="Message pi... Use / for commands, @ for files"
          ></textarea>
          ${shellMode ? html`<div class="mode-hint">Shell command${inputMode.excludeFromContext ? " · excluded from context" : ""}</div>` : null}
-          <autocomplete-menu .items=${this.completions} .selectedIndex=${this.selectedIndex} .onPick=${(item: CompletionItem) => this.pick(item)}></autocomplete-menu>
+          <autocomplete-menu .items=${this.completions} .selectedIndex=${this.selectedIndex} .onPick=${(item: CompletionItem) => { this.pick(item); }}></autocomplete-menu>
        </div>
-        <button ?disabled=${this.disabled} @click=${this.send}>Send</button>
+        <button ?disabled=${this.disabled} @click=${() => { this.send(); }}>Send</button>
        <button ?disabled=${this.disabled} title="Stop only this Pi session from continuing" @click=${() => this.onStopSession?.()}>Stop session</button>
      </footer>
    `;
@@ -61,12 +63,12 @@ export class PromptEditor extends LitElement {
    const textarea = this.textarea;
    if (!textarea) return;
    textarea.style.height = "auto";
-    textarea.style.height = `${textarea.scrollHeight}px`;
+    textarea.style.height = `${String(textarea.scrollHeight)}px`;
  }

  private updateDraft(value: string) {
    this.draft = value;
-    if (this.sessionId) saveDraft(this.sessionId, this.draft);
+    if (this.sessionId !== undefined && this.sessionId !== "") saveDraft(this.sessionId, this.draft);
    void this.refreshCompletions();
  }

@@ -74,19 +76,26 @@ export class PromptEditor extends LitElement {
    const trigger = this.currentTrigger();
    const version = ++this.requestVersion;
    this.selectedIndex = 0;
-    if (!trigger) {
+    if (trigger === undefined) {
      this.completions = [];
      return;
    }
-    if (trigger.kind === "command" && this.sessionId) {
-      const commands = await api.commands(this.sessionId).catch(() => [] as SlashCommand[]);
+    if (trigger.kind === "command" && this.sessionId !== undefined && this.sessionId !== "") {
+      const commands = await api.commands(this.sessionId).catch(emptySlashCommands);
      if (version !== this.requestVersion) return;
      this.completions = commands
        .filter((command) => command.name.toLowerCase().includes(trigger.query.toLowerCase()))
        .slice(0, 12)
-        .map((command) => ({ kind: "command", replaceFrom: trigger.from, replaceTo: this.draft.length, insertText: `/${command.name}`, detail: command.source, description: command.description }));
-    } else if (trigger.kind === "file" && this.cwd) {
-      const files = await api.files(this.cwd, trigger.query, trigger.fileKind).catch(() => [] as FileSuggestion[]);
+        .map((command) => ({
+          kind: "command",
+          replaceFrom: trigger.from,
+          replaceTo: this.draft.length,
+          insertText: `/${command.name}`,
+          detail: command.source,
+          ...(command.description === undefined ? {} : { description: command.description }),
+        }));
+    } else if (trigger.kind === "file" && this.cwd !== undefined && this.cwd !== "") {
+      const files = await api.files(this.cwd, trigger.query, trigger.fileKind).catch(emptyFileSuggestions);
      if (version !== this.requestVersion) return;
      this.completions = files
        .slice(0, 12)
@@ -119,7 +128,8 @@ export class PromptEditor extends LitElement {
      }
      if (event.key === "Tab" || event.key === "Enter") {
        event.preventDefault();
-        this.pick(this.completions[this.selectedIndex]);
+        const completion = this.completions[this.selectedIndex];
+        if (completion !== undefined) this.pick(completion);
        return;
      }
      if (event.key === "Escape") {
@@ -136,20 +146,28 @@ export class PromptEditor extends LitElement {

  private pick(item: CompletionItem) {
    this.draft = `${this.draft.slice(0, item.replaceFrom)}${item.insertText} ${this.draft.slice(item.replaceTo)}`;
-    if (this.sessionId) saveDraft(this.sessionId, this.draft);
+    if (this.sessionId !== undefined && this.sessionId !== "") saveDraft(this.sessionId, this.draft);
    this.completions = [];
  }

  private send() {
    const text = this.draft.trim();
-    if (!text || this.disabled) return;
+    if (text === "" || this.disabled) return;
    this.draft = "";
-    if (this.sessionId) clearDraft(this.sessionId);
+    if (this.sessionId !== undefined && this.sessionId !== "") clearDraft(this.sessionId);
    this.completions = [];
    this.onSend?.(text);
  }

-  static styles = promptEditorStyles;
+  static override styles = promptEditorStyles;
+}
+
+function emptySlashCommands(): SlashCommand[] {
+  return [];
+}
+
+function emptyFileSuggestions(): FileSuggestion[] {
+  return [];
 }

 const draftStoragePrefix = "pi-web:prompt-draft:";
@@ -3,6 +3,11 @@ import { customElement, property } from "lit/decorators.js";
 import type { SessionActivity, SessionInfo, SessionStatus } from "../api";
 import { listStyles } from "./shared";

+function sessionLabel(session: SessionInfo): string {
+  if (session.name !== undefined && session.name !== "") return session.name;
+  return session.firstMessage !== "" ? session.firstMessage : session.id.slice(0, 8);
+}
+
@customElement("session-list")
 export class SessionList extends LitElement {
  @property({ attribute: false }) sessions: SessionInfo[] = [];
@@ -13,13 +18,13 @@ export class SessionList extends LitElement {
  @property({ attribute: false }) onSelect?: (session: SessionInfo) => void;
  @property({ attribute: false }) onStart?: () => void;

-  render() {
+  override render() {
    return html`
      <section>
        <h2>Sessions <button ?disabled=${!this.canStart} @click=${() => this.onStart?.()}>+</button></h2>
        ${this.sessions.map((session) => html`
          <button class=${this.selected?.id === session.id ? "selected" : ""} @click=${() => this.onSelect?.(session)}>
-            <span>${session.name || session.firstMessage || session.id.slice(0, 8)}</span><small>${this.renderStatus(session)}${session.messageCount} messages</small>
+            <span>${sessionLabel(session)}</span><small>${this.renderStatus(session)}${String(session.messageCount)} messages</small>
          </button>
        `)}
      </section>
@@ -30,13 +35,13 @@ export class SessionList extends LitElement {
    const status = this.statuses[session.id];
    const activity = this.activities[session.id];
    if (activity?.phase === "active") return `● ${activity.label} · `;
-    if (!status) return "";
+    if (status === undefined) return "";
    if (status.isStreaming) return "● streaming · ";
    if (status.isBashRunning) return "● bash · ";
    if (status.isCompacting) return "● compacting · ";
-    if (status.pendingMessageCount) return `● ${status.pendingMessageCount} pending · `;
+    if (status.pendingMessageCount > 0) return `● ${String(status.pendingMessageCount)} pending · `;
    return "";
  }

-  static styles = listStyles;
+  static override styles = listStyles;
 }
@@ -10,12 +10,12 @@ export class StatusBar extends LitElement {
  @property({ attribute: false }) activity?: SessionActivity;
  @property({ attribute: false }) workspace?: Workspace;

-  render() {
+  override render() {
    const status = this.status;
-    if (!status) return html`<div class="bar muted">No session status yet</div>`;
+    if (status === undefined) return html`<div class="bar muted">No session status yet</div>`;
    const model = status.model?.id ?? "no model";
-    const provider = status.model?.provider ? `${status.model.provider}/` : "";
-    const state = status.isCompacting ? "compacting" : status.isBashRunning ? "bash" : status.isStreaming ? "running" : status.pendingMessageCount ? "queued" : "idle";
+    const provider = status.model?.provider !== undefined && status.model.provider !== "" ? `${status.model.provider}/` : "";
+    const state = status.isCompacting ? "compacting" : status.isBashRunning ? "bash" : status.isStreaming ? "running" : status.pendingMessageCount > 0 ? "queued" : "idle";
    const active = state !== "idle" || this.activity?.phase === "active";
    const context = status.contextUsage;
    const contextText = context
@@ -34,17 +34,17 @@ export class StatusBar extends LitElement {
        <span>↓${formatTokenCount(tokens.output)}</span>
        <span>${contextText}</span>
        <span>${formatCost(status.cost)}</span>
-        ${status.pendingMessageCount ? html`<span>${status.pendingMessageCount} queued</span>` : null}
+        ${status.pendingMessageCount > 0 ? html`<span>${String(status.pendingMessageCount)} queued</span>` : null}
      </div>
    `;
  }

  private activityText(state: string): string {
    const activity = this.activity;
-    if (!activity) return state;
+    if (activity === undefined) return state;
    if (state !== "idle" && activity.phase === "idle") return state;
-    return activity.detail ? `${activity.label}: ${activity.detail}` : activity.label;
+    return activity.detail !== undefined && activity.detail !== "" ? `${activity.label}: ${activity.detail}` : activity.label;
  }

-  static styles = statusBarStyles;
+  static override styles = statusBarStyles;
 }
@@ -9,7 +9,7 @@ export class WorkspaceList extends LitElement {
  @property({ attribute: false }) selected?: Workspace;
  @property({ attribute: false }) onSelect?: (workspace: Workspace) => void;

-  render() {
+  override render() {
    return html`
      <section>
        <h2>Workspaces</h2>
@@ -22,5 +22,5 @@ export class WorkspaceList extends LitElement {
    `;
  }

-  static styles = listStyles;
+  static override styles = listStyles;
 }
@@ -50,7 +50,9 @@ export const listStyles = css`

 export const chatStyles = css`
  :host { display: block; min-height: 0; color: #e6edf3; font: 14px system-ui, sans-serif; }
+  .chat-wrap { position: relative; height: 100%; min-height: 0; }
  .chat { height: 100%; overflow: auto; padding: 16px; box-sizing: border-box; }
+  .history-indicator { position: absolute; top: 10px; right: 18px; z-index: 2; display: grid; gap: 2px; max-width: min(320px, calc(100% - 36px)); border: 1px solid #30363d; border-radius: 8px; background: #0d1117dd; color: #8b949e; padding: 6px 8px; font-size: 12px; text-align: right; pointer-events: none; box-shadow: 0 8px 24px #0006; }
  .msg { margin: 0 0 14px; padding: 12px; border: 1px solid #30363d; border-radius: 10px; background: #161b22; }
  .msg.user { border-color: #2f81f7; background: #0d2847; }
  .msg.tool { border-color: #6e5200; background: #1f1a10; color: #d29922; }
@@ -64,6 +66,8 @@ export const chatStyles = css`
  .group-msg.tool { color: #d29922; }
  .group-msg.system { color: #ff7b72; }
  .group-msg.bash { color: #3fb950; }
+  .history-boundary { display: grid; gap: 3px; margin: 0 0 14px; color: #8b949e; font-size: 12px; text-align: center; }
+  .history-boundary small { color: #6e7681; }
  .label { display: block; margin-bottom: 8px; color: #8b949e; font-size: 12px; text-transform: uppercase; }
  formatted-text.part { display: block; }
  .part + .part { margin-top: 10px; }
@@ -16,7 +16,7 @@ export class ProjectController {

  async addProject() {
    const path = prompt("Project folder path");
-    if (!path) return;
+    if (path === null || path === "") return;
    try {
      const project = await api.addProject(path);
      const projects = this.getState().projects;
@@ -1,4 +1,6 @@
 import { api, type CommandResult, type SessionActivity, type SessionInfo, type SessionStatus } from "../api";
+
+const MESSAGE_PAGE_SIZE = 100;
 import { normalizeMessages, textMessage } from "../chatMessages";
 import { applyTranscriptEvent } from "../chatTranscript";
 import { isShellInput } from "../inputModes";
@@ -25,7 +27,7 @@ export class SessionController {

  clearActiveSession() {
    this.socket.close();
-    this.setState({ selectedSession: undefined, messages: [], status: undefined, activity: undefined });
+    this.setState({ selectedSession: undefined, messages: [], messagePageStart: 0, messagePageTotal: 0, isLoadingEarlierMessages: false, status: undefined, activity: undefined });
  }

  async startSession() {
@@ -40,22 +42,42 @@ export class SessionController {
    }
  }

-  async selectSession(session: SessionInfo, options?: { updateUrl?: boolean }) {
+  async selectSession(session: SessionInfo, options?: { updateUrl?: boolean | undefined }) {
    this.socket.close();
    try {
      const buffered: SessionUiEvent[] = [];
      this.socket.connect(session.id, (event) => buffered.push(event));
-      const [messages, status] = await Promise.all([api.messages(session.id), api.status(session.id)]);
-      this.setState({ selectedSession: session, messages: normalizeMessages(messages), status });
+      const [page, status] = await Promise.all([api.messages(session.id, { limit: MESSAGE_PAGE_SIZE }), api.status(session.id)]);
+      this.setState({ selectedSession: session, messages: normalizeMessages(page.messages), messagePageStart: page.start, messagePageTotal: page.total, isLoadingEarlierMessages: false, status });
      this.applyStatus(status);
      for (const event of buffered) this.applyEvent(event);
-      this.socket.setHandler((event) => this.applyEvent(event));
+      this.socket.setHandler((event) => { this.applyEvent(event); });
      if (options?.updateUrl !== false) this.updateUrl();
    } catch (error) {
      this.setState({ error: String(error) });
    }
  }

+  async loadEarlierMessages() {
+    const state = this.getState();
+    const session = state.selectedSession;
+    if (!session || state.isLoadingEarlierMessages || state.messagePageStart <= 0) return;
+    this.setState({ isLoadingEarlierMessages: true });
+    try {
+      const page = await api.messages(session.id, { before: state.messagePageStart, limit: MESSAGE_PAGE_SIZE });
+      if (this.getState().selectedSession?.id !== session.id) return;
+      this.setState({
+        messages: [...normalizeMessages(page.messages), ...this.getState().messages],
+        messagePageStart: page.start,
+        messagePageTotal: page.total,
+      });
+    } catch (error) {
+      this.setState({ error: String(error) });
+    } finally {
+      if (this.getState().selectedSession?.id === session.id) this.setState({ isLoadingEarlierMessages: false });
+    }
+  }
+
  async send(text: string) {
    const trimmed = text.trim();
    if (trimmed.startsWith("/")) return this.runCommand(text);
@@ -126,7 +148,7 @@ export class SessionController {
      return;
    }
    const message = result.type === "unsupported" ? result.message : result.message;
-    if (message) this.setState({ messages: [...this.getState().messages, textMessage(result.type === "unsupported" ? "system" : "tool", message)] });
+    if (message !== undefined && message !== "") this.setState({ messages: [...this.getState().messages, textMessage(result.type === "unsupported" ? "system" : "tool", message)] });
    if (result.type === "done" && result.session) {
      const current = this.getState().selectedSession;
      const sessions = [result.session, ...this.getState().sessions.filter((session) => session.id !== result.session?.id)];
@@ -5,7 +5,7 @@ export type SetState = (patch: Partial<AppState>) => void;
 export type UpdateUrl = () => void;

 export interface RouteTarget {
-  workspaceId?: string;
-  sessionId?: string;
-  updateUrl?: boolean;
+  workspaceId?: string | undefined;
+  sessionId?: string | undefined;
+  updateUrl?: boolean | undefined;
 }
@@ -16,7 +16,7 @@ export class WorkspaceController {
    try {
      const workspaces = await api.workspaces(project.id);
      this.setState({ workspaces });
-      const workspace = target?.workspaceId ? workspaces.find((w) => w.id === target.workspaceId) : workspaces[0];
+      const workspace = target?.workspaceId !== undefined && target.workspaceId !== "" ? workspaces.find((w) => w.id === target.workspaceId) : workspaces[0];
      if (workspace) await this.selectWorkspace(workspace, { sessionId: target?.sessionId, updateUrl: target?.updateUrl });
      else if (target?.updateUrl !== false) this.updateUrl();
    } catch (error) {
@@ -24,14 +24,14 @@ export class WorkspaceController {
    }
  }

-  async selectWorkspace(workspace: Workspace, target?: { sessionId?: string; updateUrl?: boolean }) {
+  async selectWorkspace(workspace: Workspace, target?: { sessionId?: string | undefined; updateUrl?: boolean | undefined }) {
    this.sessions.clearActiveSession();
    this.setState({ selectedWorkspace: workspace, sessions: [], error: "" });
    try {
      const sessions = await api.sessions(workspace.path);
      this.setState({ sessions });
      const sessionId = target?.sessionId;
-      const session = sessionId ? sessions.find((s) => s.id === sessionId || s.id.startsWith(sessionId)) : sessions[0];
+      const session = sessionId !== undefined && sessionId !== "" ? sessions.find((s) => s.id === sessionId || s.id.startsWith(sessionId)) : sessions[0];
      if (session) await this.sessions.selectSession(session, { updateUrl: target?.updateUrl });
      else if (target?.updateUrl !== false) this.updateUrl();
    } catch (error) {
@@ -1,7 +1,7 @@
 import { marked } from "marked";

 export function toSafeMarkdownHtml(text: string): string {
-  const html = marked.parse(escapeHtml(text), { async: false, breaks: true, gfm: true }) as string;
+  const html = marked.parse(escapeHtml(text), { async: false, breaks: true, gfm: true });
  return sanitizeHtml(html);
 }

@@ -15,7 +15,7 @@ function escapeHtml(text: string): string {
 function sanitizeHtml(html: string): string {
  const template = document.createElement("template");
  template.innerHTML = html;
-  template.content.querySelectorAll("script, style, iframe, object, embed").forEach((node) => node.remove());
+  template.content.querySelectorAll("script, style, iframe, object, embed").forEach((node) => { node.remove(); });
  template.content.querySelectorAll("*").forEach((element) => {
    for (const attribute of [...element.attributes]) {
      const name = attribute.name.toLowerCase();
@@ -1,7 +1,7 @@
 export interface AppRoute {
-  projectId?: string;
-  workspaceId?: string;
-  sessionId?: string;
+  projectId: string | undefined;
+  workspaceId: string | undefined;
+  sessionId: string | undefined;
 }

 export function readRoute(): AppRoute {
@@ -18,9 +18,9 @@ export function writeRoute(route: AppRoute): void {
  url.searchParams.delete("project");
  url.searchParams.delete("workspace");
  url.searchParams.delete("session");
-  if (route.projectId) url.searchParams.set("project", route.projectId);
-  if (route.workspaceId) url.searchParams.set("workspace", route.workspaceId);
-  if (route.sessionId) url.searchParams.set("session", route.sessionId);
+  if (route.projectId !== undefined && route.projectId !== "") url.searchParams.set("project", route.projectId);
+  if (route.workspaceId !== undefined && route.workspaceId !== "") url.searchParams.set("workspace", route.workspaceId);
+  if (route.sessionId !== undefined && route.sessionId !== "") url.searchParams.set("session", route.sessionId);
  const next = `${url.pathname}${url.search}${url.hash}`;
  const current = `${window.location.pathname}${window.location.search}${window.location.hash}`;
  if (next !== current) window.history.pushState({}, "", url);
@@ -13,9 +13,9 @@ export type SessionUiEvent =
  | { type: "session.error"; message: string };

 export class SessionSocket {
-  private socket?: WebSocket;
-  private sessionId?: string;
-  private onEvent?: (event: SessionUiEvent) => void;
+  private socket: WebSocket | undefined;
+  private sessionId: string | undefined;
+  private onEvent: ((event: SessionUiEvent) => void) | undefined;
  private reconnectTimer?: number;
  private reconnectDelay = 500;
  private shouldReconnect = false;
@@ -42,14 +42,14 @@ export class SessionSocket {
  }

  private open(): void {
-    if (!this.sessionId || !this.shouldReconnect) return;
+    if (this.sessionId === undefined || this.sessionId === "" || !this.shouldReconnect) return;
    const socket = sessionEvents(this.sessionId);
    this.socket = socket;
    socket.onopen = () => {
      this.reconnectDelay = 500;
    };
    socket.onmessage = (message) => void this.handleMessage(message.data);
-    socket.onerror = () => socket.close();
+    socket.onerror = () => { socket.close(); };
    socket.onclose = () => {
      if (this.socket === socket) this.socket = undefined;
      this.scheduleReconnect();
@@ -61,7 +61,7 @@ export class SessionSocket {
    window.clearTimeout(this.reconnectTimer);
    const delay = this.reconnectDelay;
    this.reconnectDelay = Math.min(this.reconnectDelay * 1.6, 5000);
-    this.reconnectTimer = window.setTimeout(() => this.open(), delay);
+    this.reconnectTimer = window.setTimeout(() => { this.open(); }, delay);
  }

  private async handleMessage(data: MessageEvent["data"]): Promise<void> {
@@ -71,8 +71,8 @@ export class SessionSocket {
 }

 export class GlobalSessionSocket {
-  private socket?: WebSocket;
-  private onEvent?: (event: Extract<SessionUiEvent, { type: "status.update" | "activity.update" }>) => void;
+  private socket: WebSocket | undefined;
+  private onEvent: ((event: Extract<SessionUiEvent, { type: "status.update" | "activity.update" }>) => void) | undefined;
  private reconnectTimer?: number;
  private reconnectDelay = 500;
  private shouldReconnect = false;
@@ -100,7 +100,7 @@ export class GlobalSessionSocket {
      this.reconnectDelay = 500;
    };
    socket.onmessage = (message) => void this.handleMessage(message.data);
-    socket.onerror = () => socket.close();
+    socket.onerror = () => { socket.close(); };
    socket.onclose = () => {
      if (this.socket === socket) this.socket = undefined;
      this.scheduleReconnect();
@@ -112,7 +112,7 @@ export class GlobalSessionSocket {
    window.clearTimeout(this.reconnectTimer);
    const delay = this.reconnectDelay;
    this.reconnectDelay = Math.min(this.reconnectDelay * 1.6, 5000);
-    this.reconnectTimer = window.setTimeout(() => this.open(), delay);
+    this.reconnectTimer = window.setTimeout(() => { this.open(); }, delay);
  }

  private async handleMessage(data: MessageEvent["data"]): Promise<void> {
@@ -121,12 +121,20 @@ export class GlobalSessionSocket {
  }
 }

-function isSessionUiEvent(event: any): event is SessionUiEvent {
-  return ["assistant.delta", "tool.start", "tool.end", "shell.start", "shell.chunk", "shell.end", "status.update", "activity.update", "command.output", "session.error"].includes(event?.type);
+function isSessionUiEvent(event: unknown): event is SessionUiEvent {
+  const type = eventType(event);
+  return ["assistant.delta", "tool.start", "tool.end", "shell.start", "shell.chunk", "shell.end", "status.update", "activity.update", "command.output", "session.error"].includes(type);
 }

 function isGlobalSessionEvent(event: unknown): event is Extract<SessionUiEvent, { type: "status.update" | "activity.update" }> {
-  return typeof event === "object" && event !== null && ("type" in event) && ((event as any).type === "status.update" || (event as any).type === "activity.update");
+  const type = eventType(event);
+  return type === "status.update" || type === "activity.update";
+}
+
+function eventType(event: unknown): string {
+  if (typeof event !== "object" || event === null || !("type" in event)) return "";
+  const type = event.type;
+  return typeof type === "string" ? type : "";
 }

 async function parseSocketEvent(data: MessageEvent["data"]): Promise<unknown> {
@@ -141,12 +149,12 @@ async function parseSocketEvent(data: MessageEvent["data"]): Promise<unknown> {
 }

 function closeSocketQuietly(socket: WebSocket | undefined): void {
-  if (!socket) return;
+  if (socket === undefined) return;
  socket.onmessage = null;
  socket.onerror = null;
  socket.onclose = null;
  if (socket.readyState === WebSocket.CONNECTING) {
-    socket.onopen = () => socket.close();
+    socket.onopen = () => { socket.close(); };
    return;
  }
  socket.close();
@@ -3,7 +3,7 @@ import type { ChatLine } from "./components/shared";
 import type { SessionUiEvent } from "./sessionSocket";

 export function shellStartMessage(command: string, excludeFromContext?: boolean): ChatLine {
-  return textMessage("bash", `${excludeFromContext ? "excluded from context\n\n" : ""}$ ${command}`);
+  return textMessage("bash", `${excludeFromContext === true ? "excluded from context\n\n" : ""}$ ${command}`);
 }

 export function appendShellChunk(messages: ChatLine[], chunk: string): ChatLine[] {
@@ -19,13 +19,13 @@ export function finalizeShellMessage(messages: ChatLine[], event: Extract<Sessio
  const lastPart = last?.parts.at(-1);
  if (last?.role !== "bash" || lastPart?.type !== "text") return messages;
  const notes: string[] = [];
-  if (!lastPart.text.includes("\n\n") && !event.output) notes.push("(no output)");
-  if (event.isError) notes.push(event.output ?? "Bash command failed");
-  if (event.exitCode != null) notes.push(`exit ${event.exitCode}`);
-  if (event.cancelled) notes.push("cancelled");
-  if (event.truncated) notes.push("output truncated");
-  if (event.fullOutputPath) notes.push(`full output: ${event.fullOutputPath}`);
-  if (!notes.length) return messages;
+  if (!lastPart.text.includes("\n\n") && (event.output === undefined || event.output === "")) notes.push("(no output)");
+  if (event.isError === true) notes.push(event.output ?? "Bash command failed");
+  if (event.exitCode != null) notes.push(`exit ${String(event.exitCode)}`);
+  if (event.cancelled === true) notes.push("cancelled");
+  if (event.truncated === true) notes.push("output truncated");
+  if (event.fullOutputPath !== undefined && event.fullOutputPath !== "") notes.push(`full output: ${event.fullOutputPath}`);
+  if (notes.length === 0) return messages;
  return [...messages.slice(0, -1), { ...last, parts: [...last.parts.slice(0, -1), { ...lastPart, text: `${lastPart.text}\n\n${notes.join("\n")}` }] }];
 }

@@ -2,9 +2,9 @@ export function formatTokenCount(count: number): string {
  if (!Number.isFinite(count)) return "0";
  if (count < 1000) return Math.round(count).toString();
  if (count < 10_000) return `${(count / 1000).toFixed(1)}k`;
-  if (count < 1_000_000) return `${Math.round(count / 1000)}k`;
+  if (count < 1_000_000) return `${String(Math.round(count / 1000))}k`;
  if (count < 10_000_000) return `${(count / 1_000_000).toFixed(1)}M`;
-  return `${Math.round(count / 1_000_000)}M`;
+  return `${String(Math.round(count / 1_000_000))}M`;
 }

 export function formatCost(cost: number): string {
@@ -34,10 +34,10 @@ app.get<{ Params: { projectId: string } }>("/api/projects/:projectId/workspaces"
  }
 });

-await registerSessionProxyRoutes(app);
+registerSessionProxyRoutes(app);

 app.get<{ Querystring: { cwd?: string; q?: string; kind?: "tracked" | "untracked" | "other" } }>("/api/files", async (request, reply) => {
-  if (!request.query.cwd) return reply.code(400).send({ error: "cwd query parameter is required" });
+  if (request.query.cwd === undefined || request.query.cwd === "") return reply.code(400).send({ error: "cwd query parameter is required" });
  try {
    return await listFileSuggestions(request.query.cwd, request.query.q ?? "", request.query.kind);
  } catch (error) {
@@ -51,6 +51,6 @@ if (existsSync(clientDist)) {
  app.setNotFoundHandler((_request, reply) => reply.sendFile("index.html"));
 }

-const port = Number(process.env.PI_WEB_PORT ?? process.env.PORT ?? 3000);
-const host = process.env.PI_WEB_HOST ?? "127.0.0.1";
+const port = Number(process.env["PI_WEB_PORT"] ?? process.env["PORT"] ?? 3000);
+const host = process.env["PI_WEB_HOST"] ?? "127.0.0.1";
 await app.listen({ port, host });
@@ -13,7 +13,7 @@ export class ProjectService {
    const resolved = await realpath(input.path);
    const s = await stat(resolved);
    if (!s.isDirectory()) throw new Error("Project path must be a directory");
-    return this.store.add({ name: input.name, path: resolved });
+    return this.store.add(input.name === undefined ? { path: resolved } : { name: input.name, path: resolved });
  }

  async requireProject(id: string): Promise<Project> {
@@ -11,7 +11,9 @@ export class SessionEventHub {
      this.socketsBySession.set(sessionId, sockets);
    }
    sockets.add(socket);
-    socket.on("close", () => sockets?.delete(socket));
+    socket.on("close", () => {
+      sockets.delete(socket);
+    });
  }

  addGlobal(socket: WebSocket): void {
@@ -12,12 +12,13 @@ await app.register(fastifyWebsocket);

 const eventHub = new SessionEventHub();
 const sessions = new PiSessionService(eventHub);
-await registerSessionRoutes(app, sessions, eventHub);
+registerSessionRoutes(app, sessions, eventHub);

-const port = process.env.PI_WEB_SESSIOND_PORT ? Number(process.env.PI_WEB_SESSIOND_PORT) : undefined;
-const host = process.env.PI_WEB_SESSIOND_HOST ?? "127.0.0.1";
+const portValue = process.env["PI_WEB_SESSIOND_PORT"];
+const port = portValue !== undefined && portValue !== "" ? Number(portValue) : undefined;
+const host = process.env["PI_WEB_SESSIOND_HOST"] ?? "127.0.0.1";

-if (port) {
+if (port !== undefined) {
  await app.listen({ port, host });
 } else {
  const path = sessiondSocketPath();
@@ -2,9 +2,9 @@ import { homedir } from "node:os";
 import { join } from "node:path";

 export function sessiondSocketPath(): string {
-  return process.env.PI_WEB_SESSIOND_SOCKET ?? join(homedir(), ".pi-web", "sessiond.sock");
+  return process.env["PI_WEB_SESSIOND_SOCKET"] ?? join(homedir(), ".pi-web", "sessiond.sock");
 }

 export function sessiondHttpUrl(): string | undefined {
-  return process.env.PI_WEB_SESSIOND_URL;
+  return process.env["PI_WEB_SESSIOND_URL"];
 }
@@ -8,12 +8,12 @@ export class SessionDaemonClient {

  async request(method: string, path: string, body?: unknown): Promise<{ statusCode: number; headers: Record<string, string>; body: string }> {
    const payload = body === undefined ? undefined : JSON.stringify(body);
-    if (this.baseUrl) return this.requestUrl(method, path, payload);
+    if (this.baseUrl !== undefined && this.baseUrl !== "") return this.requestUrl(method, path, payload);
    return this.requestSocket(method, path, payload);
  }

  connectWebSocket(path: string): WebSocket {
-    if (this.baseUrl) {
+    if (this.baseUrl !== undefined && this.baseUrl !== "") {
      const url = new URL(path, this.baseUrl);
      url.protocol = url.protocol === "https:" ? "wss:" : "ws:";
      return new WebSocket(url);
@@ -22,11 +22,12 @@ export class SessionDaemonClient {
  }

  private async requestUrl(method: string, path: string, payload?: string) {
-    const response = await fetch(new URL(path, this.baseUrl), {
-      method,
-      headers: payload ? { "content-type": "application/json" } : undefined,
-      body: payload,
-    });
+    const init: RequestInit = { method };
+    if (payload !== undefined && payload !== "") {
+      init.headers = { "content-type": "application/json" };
+      init.body = payload;
+    }
+    const response = await fetch(new URL(path, this.baseUrl), init);
    return {
      statusCode: response.status,
      headers: Object.fromEntries(response.headers.entries()),
@@ -41,13 +42,15 @@ export class SessionDaemonClient {
          socketPath: this.socketPath,
          path,
          method,
-          headers: payload
+          headers: payload !== undefined && payload !== ""
            ? { "content-type": "application/json", "content-length": Buffer.byteLength(payload) }
            : undefined,
        },
        (response) => {
-          const chunks: Buffer[] = [];
-          response.on("data", (chunk) => chunks.push(Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk)));
+          const chunks: Uint8Array[] = [];
+          response.on("data", (chunk: Buffer | string) => {
+            chunks.push(Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk));
+          });
          response.on("end", () => {
            resolve({
              statusCode: response.statusCode ?? 500,
@@ -58,7 +61,7 @@ export class SessionDaemonClient {
        },
      );
      request.on("error", reject);
-      if (payload) request.write(payload);
+      if (payload !== undefined && payload !== "") request.write(payload);
      request.end();
    });
  }
@@ -2,15 +2,17 @@ import type { FastifyInstance, FastifyReply } from "fastify";
 import { WebSocket, type RawData } from "ws";
 import { SessionDaemonClient } from "./sessionDaemonClient.js";

-export async function registerSessionProxyRoutes(app: FastifyInstance, daemon = new SessionDaemonClient()): Promise<void> {
+export function registerSessionProxyRoutes(app: FastifyInstance, daemon = new SessionDaemonClient()): void {
  const proxy = async (request: { method: string; url: string; body?: unknown }, reply: FastifyReply) => {
    try {
      const upstream = await daemon.request(request.method, stripApiPrefix(request.url), request.body);
      reply.code(upstream.statusCode);
-      if (upstream.headers["content-type"]) reply.header("content-type", upstream.headers["content-type"]);
-      return upstream.body ? JSON.parse(upstream.body) : undefined;
+      const contentType = upstream.headers["content-type"];
+      if (contentType !== undefined && contentType !== "") reply.header("content-type", contentType);
+      return upstream.body !== "" ? parseJson(upstream.body) : undefined;
    } catch (error) {
      requestFailed(reply, error);
+      return undefined;
    }
  };

@@ -36,22 +38,30 @@ export async function registerSessionProxyRoutes(app: FastifyInstance, daemon =
 }

 function stripApiPrefix(url: string): string {
-  return url.startsWith("/api") ? url.slice(4) || "/" : url;
+  const stripped = url.startsWith("/api") ? url.slice(4) : url;
+  return stripped === "" ? "/" : stripped;
 }

-function requestFailed(reply: FastifyReply, error: unknown) {
+function parseJson(text: string): unknown {
+  const value: unknown = JSON.parse(text);
+  return value;
+}
+
+function requestFailed(reply: FastifyReply, error: unknown): void {
  reply.code(502).send({ error: `Session daemon unavailable: ${error instanceof Error ? error.message : String(error)}` });
 }

 function bridgeSockets(client: WebSocket, upstream: WebSocket): void {
-  client.on("message", (data) => sendIfOpen(upstream, data));
-  upstream.on("message", (data) => sendIfOpen(client, data));
-  client.on("close", () => upstream.close());
-  upstream.on("close", () => client.close());
-  upstream.on("error", () => client.close());
-  client.on("error", () => upstream.close());
+  client.on("message", (data) => { sendIfOpen(upstream, data); });
+  upstream.on("message", (data) => { sendIfOpen(client, data); });
+  client.on("close", () => { upstream.close(); });
+  upstream.on("close", () => { client.close(); });
+  upstream.on("error", () => { client.close(); });
+  client.on("error", () => { upstream.close(); });
 }

 function sendIfOpen(socket: WebSocket, data: RawData): void {
-  if (socket.readyState === WebSocket.OPEN) socket.send(data);
+  if (socket.readyState === WebSocket.OPEN) {
+    socket.send(data);
+  }
 }
@@ -7,15 +7,18 @@ import {
  ModelRegistry,
  SessionManager,
  type AgentSession,
-  type AgentSessionRuntime,
  type CreateAgentSessionRuntimeFactory,
 } from "@mariozechner/pi-coding-agent";
-import type { ClientCommand, ClientCommandResult, ClientSession, ClientSessionStatus } from "../types.js";
+import type { ClientCommand, ClientCommandResult, ClientMessagePage, ClientSession, ClientSessionStatus } from "../types.js";
 import type { SessionEventHub } from "../realtime/sessionEventHub.js";
 import { BUILTIN_COMMANDS } from "./builtinCommands.js";
 import { SessionCommandService } from "./sessionCommandService.js";
 import type { ActiveSession } from "./sessionRuntimeStore.js";

+function noop(): void {
+  // Intentionally empty default unsubscribe callback.
+}
+
 export class PiSessionService {
  private readonly active = new Map<string, ActiveSession>();
  private readonly activities = new Map<string, { phase: "active" | "idle" | "error"; label: string; detail?: string; at: string }>();
@@ -26,12 +29,15 @@ export class PiSessionService {
  private readonly modelRegistry = ModelRegistry.create(this.authStorage);
  private readonly createRuntime: CreateAgentSessionRuntimeFactory = async ({ cwd, agentDir, sessionManager, sessionStartEvent }) => {
    const services = await createAgentSessionServices({ cwd, agentDir, authStorage: this.authStorage, modelRegistry: this.modelRegistry });
-    const result = await createAgentSessionFromServices({ services, sessionManager, sessionStartEvent });
+    const options = sessionStartEvent === undefined
+      ? { services, sessionManager }
+      : { services, sessionManager, sessionStartEvent };
+    const result = await createAgentSessionFromServices(options);
    return { ...result, services, diagnostics: services.diagnostics };
  };

  constructor(private readonly events: SessionEventHub) {
-    this.heartbeat = setInterval(() => this.publishHeartbeats(), 2000);
+    this.heartbeat = setInterval(() => { this.publishHeartbeats(); }, 2000);
    this.commandService = new SessionCommandService(
      (sessionId) => this.getActive(sessionId),
      (sessionId, text) => this.prompt(sessionId, text),
@@ -45,7 +51,7 @@ export class PiSessionService {
      id: s.id,
      path: s.path,
      cwd: s.cwd,
-      name: s.name,
+      ...(s.name === undefined ? {} : { name: s.name }),
      created: s.created.toISOString(),
      modified: s.modified.toISOString(),
      messageCount: s.messageCount,
@@ -67,9 +73,15 @@ export class PiSessionService {
    };
  }

-  async messages(sessionId: string): Promise<unknown[]> {
+  async messages(sessionId: string, page?: { before?: number; limit?: number }): Promise<unknown[] | ClientMessagePage> {
    const session = await this.getOrOpen(sessionId);
-    return session.messages;
+    const messages = historyMessages(session);
+    if (page?.before === undefined && page?.limit === undefined) return messages;
+    const total = messages.length;
+    const before = clampInteger(page.before ?? total, 0, total);
+    const limit = clampInteger(page.limit ?? 100, 1, 500);
+    const start = Math.max(0, before - limit);
+    return { messages: messages.slice(start, before), start, total };
  }

  async status(sessionId: string): Promise<ClientSessionStatus> {
@@ -80,7 +92,7 @@ export class PiSessionService {
    const session = await this.getOrOpen(sessionId);
    const commands: ClientCommand[] = [...BUILTIN_COMMANDS];
    for (const command of session.extensionRunner.getRegisteredCommands()) {
-      commands.push({ name: command.invocationName, description: command.description, source: "extension" });
+      commands.push({ name: command.invocationName, ...(command.description === undefined ? {} : { description: command.description }), source: "extension" });
    }
    for (const template of session.promptTemplates) {
      commands.push({ name: template.name, description: template.description, source: "prompt" });
@@ -94,7 +106,7 @@ export class PiSessionService {
  async prompt(sessionId: string, text: string): Promise<void> {
    const session = await this.getOrOpen(sessionId);
    this.publishActivity(session, "prompt accepted", "active");
-    void session.prompt(text).catch((error) => {
+    void session.prompt(text).catch((error: unknown) => {
      const message = error instanceof Error ? error.message : String(error);
      this.publishActivity(session, "error", "error", message);
      this.events.publish(sessionId, { type: "session.error", message });
@@ -126,7 +138,7 @@ export class PiSessionService {
      });
      this.publishActivity(session, "bash complete", result.exitCode === 0 ? "idle" : "error", command);
      this.publishStatus(session);
-    }).catch((error) => {
+    }).catch((error: unknown) => {
      const message = error instanceof Error ? error.message : String(error);
      this.events.publish(session.sessionId, { type: "shell.end", output: message, isError: true });
      this.events.publish(session.sessionId, { type: "session.error", message });
@@ -172,9 +184,12 @@ export class PiSessionService {

  private async create(sessionManager: SessionManager, cwd: string): Promise<ActiveSession> {
    const runtime = await createAgentSessionRuntime(this.createRuntime, { cwd, agentDir: this.agentDir, sessionManager });
-    const active: ActiveSession = { runtime, unsubscribe: () => {} };
+    const active: ActiveSession = { runtime, unsubscribe: noop };
    this.bindRuntime(active);
-    runtime.setRebindSession(async () => this.bindRuntime(active));
+    runtime.setRebindSession(() => {
+      this.bindRuntime(active);
+      return Promise.resolve();
+    });
    this.active.set(runtime.session.sessionId, active);
    this.publishStatus(runtime.session);
    return active;
@@ -214,9 +229,11 @@ export class PiSessionService {
    return "active";
  }

-  private publishActivityForEvent(session: AgentSession, event: any): void {
-    if (event.type === "agent_start") return this.publishActivity(session, "agent running", "active");
-    if (event.type === "agent_end") {
+  private publishActivityForEvent(session: AgentSession, event: unknown): void {
+    const eventType = getString(event, "type");
+    if (eventType === undefined) return;
+    if (eventType === "agent_start") { this.publishActivity(session, "agent running", "active"); return; }
+    if (eventType === "agent_end") {
      this.publishActivity(session, "idle", "idle");
      setTimeout(() => {
        this.publishActivity(session, "idle", "idle");
@@ -224,21 +241,26 @@ export class PiSessionService {
      }, 250);
      return;
    }
-    if (event.type === "turn_end") return this.publishActivity(session, "turn complete", "active");
-    if (event.type === "message_start") return this.publishActivity(session, "message started", "active");
-    if (event.type === "message_end") return this.publishActivity(session, "message complete", "idle");
-    if (event.type === "message_update") return this.publishActivity(session, "receiving response", "active");
-    if (event.type === "tool_execution_start") return this.publishActivity(session, "running tool", "active", event.toolName);
-    if (event.type === "tool_execution_end") return this.publishActivity(session, event.isError ? "tool failed" : "tool complete", event.isError ? "error" : "active", event.toolName);
-    if (event.type === "bash_execution_start") return this.publishActivity(session, "running bash", "active");
-    if (event.type === "bash_execution_end") return this.publishActivity(session, "bash complete", "active");
-    this.publishActivity(session, event.type.replaceAll("_", " "), "active");
+    if (eventType === "turn_end") { this.publishActivity(session, "turn complete", "active"); return; }
+    if (eventType === "message_start") { this.publishActivity(session, "message started", "active"); return; }
+    if (eventType === "message_end") { this.publishActivity(session, "message complete", "idle"); return; }
+    if (eventType === "message_update") { this.publishActivity(session, "receiving response", "active"); return; }
+    if (eventType === "tool_execution_start") { this.publishActivity(session, "running tool", "active", getString(event, "toolName")); return; }
+    if (eventType === "tool_execution_end") {
+      const isError = getBoolean(event, "isError") === true;
+      this.publishActivity(session, isError ? "tool failed" : "tool complete", isError ? "error" : "active", getString(event, "toolName"));
+      return;
+    }
+    if (eventType === "bash_execution_start") { this.publishActivity(session, "running bash", "active"); return; }
+    if (eventType === "bash_execution_end") { this.publishActivity(session, "bash complete", "active"); return; }
+    this.publishActivity(session, eventType.replaceAll("_", " "), "active");
  }

  private publishActivity(session: AgentSession, label: string, phase: "active" | "idle" | "error", detail?: string): void {
    const at = new Date().toISOString();
-    this.activities.set(session.sessionId, { phase, label, detail, at });
-    const activity = { sessionId: session.sessionId, phase, label, detail, at };
+    const stored = detail === undefined ? { phase, label, at } : { phase, label, detail, at };
+    this.activities.set(session.sessionId, stored);
+    const activity = detail === undefined ? { sessionId: session.sessionId, phase, label, at } : { sessionId: session.sessionId, phase, label, detail, at };
    this.events.publish(session.sessionId, { type: "activity.update", activity });
    this.events.publishGlobal({ type: "activity.update", activity });
  }
@@ -251,17 +273,23 @@ export class PiSessionService {

  private statusFromSession(session: AgentSession): ClientSessionStatus {
    const stats = session.getSessionStats();
-    return {
-      sessionId: session.sessionId,
-      model: session.model
-        ? {
+    const model = session.model === undefined
+      ? undefined
+      : (() => {
+          const name = getString(session.model, "name");
+          const reasoning = getProperty(session.model, "reasoning");
+          return {
            provider: session.model.provider,
            id: session.model.id,
-            name: (session.model as any).name,
+            ...(name === undefined ? {} : { name }),
            contextWindow: session.model.contextWindow,
-            reasoning: (session.model as any).reasoning,
-          }
-        : undefined,
+            ...(reasoning === undefined ? {} : { reasoning }),
+          };
+        })();
+    const contextUsage = session.getContextUsage();
+    return {
+      sessionId: session.sessionId,
+      ...(model === undefined ? {} : { model }),
      thinkingLevel: session.thinkingLevel,
      isStreaming: session.isStreaming,
      isCompacting: session.isCompacting,
@@ -269,33 +297,54 @@ export class PiSessionService {
      pendingMessageCount: session.pendingMessageCount,
      tokens: stats.tokens,
      cost: stats.cost,
-      contextUsage: session.getContextUsage(),
+      ...(contextUsage === undefined ? {} : { contextUsage }),
    };
  }
 }

-function toClientEvent(event: any): unknown {
-  if (event.type === "message_update" && event.assistantMessageEvent?.type === "text_delta") {
-    return { type: "assistant.delta", text: event.assistantMessageEvent.delta };
+function historyMessages(session: AgentSession): unknown[] {
+  const messages: unknown[] = [];
+  for (const entry of session.sessionManager.getBranch()) {
+    if (entry.type === "message") messages.push(entry.message);
+    else if (entry.type === "custom_message" && entry.display) messages.push({ role: "custom", content: entry.content, customType: entry.customType, details: entry.details });
+    else if (entry.type === "compaction") messages.push({ role: "system", content: `Compacted history:\n\n${entry.summary}` });
+    else if (entry.type === "branch_summary") messages.push({ role: "system", content: `Branch summary:\n\n${entry.summary}` });
  }
-  if (event.type === "tool_execution_start") {
-    return { type: "tool.start", toolName: event.toolName, toolCallId: event.toolCallId, summary: summarizeToolArgs(event.args) };
-  }
-  if (event.type === "tool_execution_end") {
-    return { type: "tool.end", toolName: event.toolName, toolCallId: event.toolCallId, text: stringifyToolResult(event.result), isError: event.isError };
-  }
-  if (event.type === "agent_start") return { type: "agent.start" };
-  if (event.type === "agent_end") return { type: "agent.end" };
-  if (event.type === "message_end") return { type: "message.end" };
-  return { type: "pi.event", eventType: event.type };
+  return messages;
 }

-function summarizeToolArgs(args: any): string {
-  if (!args || typeof args !== "object") return args == null ? "" : String(args);
-  if (typeof args.command === "string") return args.command;
-  if (typeof args.path === "string") return args.path;
-  if (typeof args.oldText === "string" && typeof args.newText === "string") return "edit text replacement";
-  if (Array.isArray(args.edits)) return `${args.edits.length} edit${args.edits.length === 1 ? "" : "s"}`;
+function clampInteger(value: number, min: number, max: number): number {
+  if (!Number.isFinite(value)) return max;
+  return Math.max(min, Math.min(max, Math.floor(value)));
+}
+
+function toClientEvent(event: unknown): unknown {
+  const eventType = getString(event, "type");
+  const assistantMessageEvent = getProperty(event, "assistantMessageEvent");
+  if (eventType === "message_update" && getString(assistantMessageEvent, "type") === "text_delta") {
+    return { type: "assistant.delta", text: getString(assistantMessageEvent, "delta") ?? "" };
+  }
+  if (eventType === "tool_execution_start") {
+    return { type: "tool.start", toolName: getString(event, "toolName") ?? "", toolCallId: getString(event, "toolCallId") ?? "", summary: summarizeToolArgs(getProperty(event, "args")) };
+  }
+  if (eventType === "tool_execution_end") {
+    return { type: "tool.end", toolName: getString(event, "toolName") ?? "", toolCallId: getString(event, "toolCallId") ?? "", text: stringifyToolResult(getProperty(event, "result")), isError: getBoolean(event, "isError") === true };
+  }
+  if (eventType === "agent_start") return { type: "agent.start" };
+  if (eventType === "agent_end") return { type: "agent.end" };
+  if (eventType === "message_end") return { type: "message.end" };
+  return { type: "pi.event", eventType: eventType ?? "unknown" };
+}
+
+function summarizeToolArgs(args: unknown): string {
+  if (!isRecord(args)) return stringifyPrimitive(args);
+  const command = getString(args, "command");
+  if (command !== undefined) return command;
+  const path = getString(args, "path");
+  if (path !== undefined) return path;
+  if (typeof args["oldText"] === "string" && typeof args["newText"] === "string") return "edit text replacement";
+  const edits = args["edits"];
+  if (Array.isArray(edits)) return `${String(edits.length)} edit${edits.length === 1 ? "" : "s"}`;
  const entries = Object.entries(args).filter(([, value]) => value != null).slice(0, 3);
  return entries.map(([key, value]) => `${key}: ${shortToolValue(value)}`).join(" · ");
 }
@@ -303,18 +352,43 @@ function summarizeToolArgs(args: any): string {
 function shortToolValue(value: unknown): string {
  if (typeof value === "string") return value.length > 80 ? `${value.slice(0, 77)}…` : value;
  if (typeof value === "number" || typeof value === "boolean") return String(value);
-  if (Array.isArray(value)) return `${value.length} item${value.length === 1 ? "" : "s"}`;
-  if (typeof value === "object" && value) return "object";
+  if (Array.isArray(value)) return `${String(value.length)} item${value.length === 1 ? "" : "s"}`;
+  if (typeof value === "object" && value !== null) return "object";
  return "";
 }

 function stringifyToolResult(result: unknown): string {
  if (typeof result === "string") return result;
-  if (Array.isArray(result)) return result.map(stringifyToolResult).filter(Boolean).join("\n");
-  if (result && typeof result === "object") {
-    const text = (result as any).text ?? (result as any).content ?? (result as any).output;
-    if (typeof text === "string") return text;
+  if (Array.isArray(result)) return result.map(stringifyToolResult).filter((text) => text !== "").join("\n");
+  if (isRecord(result)) {
+    const text = getString(result, "text") ?? getString(result, "content") ?? getString(result, "output");
+    if (text !== undefined) return text;
    return JSON.stringify(result, null, 2);
  }
-  return result == null ? "" : String(result);
+  return stringifyPrimitive(result);
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null;
+}
+
+function getProperty(value: unknown, key: string): unknown {
+  return isRecord(value) ? value[key] : undefined;
+}
+
+function getString(value: unknown, key: string): string | undefined {
+  const property = getProperty(value, key);
+  return typeof property === "string" ? property : undefined;
+}
+
+function getBoolean(value: unknown, key: string): boolean | undefined {
+  const property = getProperty(value, key);
+  return typeof property === "boolean" ? property : undefined;
+}
+
+function stringifyPrimitive(value: unknown): string {
+  if (value == null) return "";
+  if (typeof value === "string") return value;
+  if (typeof value === "number" || typeof value === "boolean" || typeof value === "bigint") return String(value);
+  return "";
 }
@@ -44,26 +44,23 @@ export class SessionCommandService {

  async respond(sessionId: string, requestId: string, value: string): Promise<ClientCommandResult> {
    const pending = this.pendingSelects.get(requestId);
-    if (!pending || pending.sessionId !== sessionId) return { type: "unsupported", message: "Command request expired" };
+    if (pending?.sessionId !== sessionId) return { type: "unsupported", message: "Command request expired" };
    this.pendingSelects.delete(requestId);

    const active = await this.getActive(sessionId);
-    if (pending.command === "fork") {
-      const result = await active.runtime.fork(value);
-      if (result.cancelled) return { type: "done", message: "Fork cancelled" };
-      return { type: "done", message: "Session forked", session: clientSessionFromRuntime(active.runtime) };
-    }
-    return { type: "unsupported", message: "Unsupported command response" };
+    const result = await active.runtime.fork(value);
+    if (result.cancelled) return { type: "done", message: "Fork cancelled" };
+    return { type: "done", message: "Session forked", session: clientSessionFromRuntime(active.runtime) };
  }

  private nameSession(active: ActiveSession, name: string): ClientCommandResult {
-    if (!name) return { type: "unsupported", message: "Usage: /name <session name>" };
+    if (name === "") return { type: "unsupported", message: "Usage: /name <session name>" };
    active.runtime.session.setSessionName(name);
    return { type: "done", message: `Session named: ${name}`, session: clientSessionFromRuntime(active.runtime) };
  }

  private compact(session: AgentSession, instructions: string): ClientCommandResult {
-    void session.compact(instructions || undefined)
+    void session.compact(instructions === "" ? undefined : instructions)
      .then((result) => {
        this.events.publish(session.sessionId, {
          type: "command.output",
@@ -71,7 +68,7 @@ export class SessionCommandService {
          message: formatCompactionResult(result),
        });
      })
-      .catch((error) => {
+      .catch((error: unknown) => {
        const message = error instanceof Error ? error.message : String(error);
        this.events.publish(session.sessionId, { type: "command.output", level: "error", message: `Compaction failed: ${message}` });
        this.events.publish(session.sessionId, { type: "session.error", message });
@@ -81,7 +78,7 @@ export class SessionCommandService {

  private async clone(active: ActiveSession): Promise<ClientCommandResult> {
    const leafId = active.runtime.session.sessionManager.getLeafId();
-    if (!leafId) return { type: "unsupported", message: "Cannot clone: no current session entry" };
+    if (leafId === null || leafId === "") return { type: "unsupported", message: "Cannot clone: no current session entry" };
    const result = await active.runtime.fork(leafId, { position: "at" });
    if (result.cancelled) return { type: "done", message: "Clone cancelled" };
    return { type: "done", message: "Session cloned", session: clientSessionFromRuntime(active.runtime) };
@@ -113,7 +110,7 @@ function clientSessionFromRuntime(runtime: AgentSessionRuntime): ClientSession {
    id: session.sessionId,
    path: session.sessionFile ?? "",
    cwd: runtime.cwd,
-    name: session.sessionName,
+    ...(session.sessionName === undefined ? {} : { name: session.sessionName }),
    created: new Date().toISOString(),
    modified: new Date().toISOString(),
    messageCount: session.messages.length,
@@ -125,9 +122,9 @@ function formatSessionStats(session: AgentSession): string {
  const stats = session.getSessionStats();
  return [
    `Session: ${stats.sessionId}`,
-    `Messages: ${stats.totalMessages} (${stats.userMessages} user, ${stats.assistantMessages} assistant)`,
-    `Tool calls: ${stats.toolCalls}`,
-    `Tokens: ↑${stats.tokens.input} ↓${stats.tokens.output} total ${stats.tokens.total}`,
+    `Messages: ${String(stats.totalMessages)} (${String(stats.userMessages)} user, ${String(stats.assistantMessages)} assistant)`,
+    `Tool calls: ${String(stats.toolCalls)}`,
+    `Tokens: ↑${String(stats.tokens.input)} ↓${String(stats.tokens.output)} total ${String(stats.tokens.total)}`,
    `Cost: $${stats.cost.toFixed(4)}`,
  ].join("\n");
 }
@@ -135,7 +132,7 @@ function formatSessionStats(session: AgentSession): string {
 function formatCompactionResult(result: { summary: string; tokensBefore: number }): string {
  return [
    "Compaction complete.",
-    `Tokens before: ${result.tokensBefore}`,
+    `Tokens before: ${String(result.tokensBefore)}`,
    "",
    result.summary,
  ].join("\n");
@@ -2,9 +2,9 @@ import type { FastifyInstance } from "fastify";
 import type { SessionEventHub } from "../realtime/sessionEventHub.js";
 import type { PiSessionService } from "./piSessionService.js";

-export async function registerSessionRoutes(app: FastifyInstance, sessions: PiSessionService, eventHub: SessionEventHub, prefix = ""): Promise<void> {
+export function registerSessionRoutes(app: FastifyInstance, sessions: PiSessionService, eventHub: SessionEventHub, prefix = ""): void {
  app.get<{ Querystring: { cwd?: string } }>(`${prefix}/sessions`, async (request, reply) => {
-    if (!request.query.cwd) return reply.code(400).send({ error: "cwd query parameter is required" });
+    if (request.query.cwd === undefined || request.query.cwd === "") return reply.code(400).send({ error: "cwd query parameter is required" });
    return sessions.list(request.query.cwd);
  });

@@ -16,9 +16,10 @@ export async function registerSessionRoutes(app: FastifyInstance, sessions: PiSe
    }
  });

-  app.get<{ Params: { sessionId: string } }>(`${prefix}/sessions/:sessionId/messages`, async (request, reply) => {
+  app.get<{ Params: { sessionId: string }; Querystring: { before?: string; limit?: string } }>(`${prefix}/sessions/:sessionId/messages`, async (request, reply) => {
    try {
-      return await sessions.messages(request.params.sessionId);
+      const page = { ...optionalField("before", optionalNumber(request.query.before)), ...optionalField("limit", optionalNumber(request.query.limit)) };
+      return await sessions.messages(request.params.sessionId, page);
    } catch (error) {
      return reply.code(404).send({ error: error instanceof Error ? error.message : String(error) });
    }
@@ -79,7 +80,7 @@ export async function registerSessionRoutes(app: FastifyInstance, sessions: PiSe
    return { aborted: true };
  });

-  app.post<{ Params: { sessionId: string } }>(`${prefix}/sessions/:sessionId/stop`, async (request) => {
+  app.post<{ Params: { sessionId: string } }>(`${prefix}/sessions/:sessionId/stop`, (request) => {
    sessions.stop(request.params.sessionId);
    return { stopped: true };
  });
@@ -92,3 +93,13 @@ export async function registerSessionRoutes(app: FastifyInstance, sessions: PiSe
    eventHub.addGlobal(socket);
  });
 }
+
+function optionalField<T>(key: string, value: T | undefined): Record<string, T> | object {
+  return value === undefined ? {} : { [key]: value };
+}
+
+function optionalNumber(value: string | undefined): number | undefined {
+  if (value === undefined || value === "") return undefined;
+  const parsed = Number(value);
+  return Number.isFinite(parsed) ? parsed : undefined;
+}
@@ -8,6 +8,29 @@ interface ProjectFile {
  projects: Project[];
 }

+function isNodeErrorWithCode(error: unknown, code: string): error is NodeJS.ErrnoException {
+  return error instanceof Error && "code" in error && error.code === code;
+}
+
+function parseProjectFile(value: unknown): ProjectFile {
+  if (!isRecord(value) || !Array.isArray(value["projects"])) throw new Error("Invalid project file");
+  return { projects: value["projects"].map(parseProject) };
+}
+
+function parseProject(value: unknown): Project {
+  if (!isRecord(value)) throw new Error("Invalid project");
+  const id = value["id"];
+  const name = value["name"];
+  const path = value["path"];
+  const createdAt = value["createdAt"];
+  if (typeof id !== "string" || typeof name !== "string" || typeof path !== "string" || typeof createdAt !== "string") throw new Error("Invalid project");
+  return { id, name, path, createdAt };
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null;
+}
+
 export class ProjectStore {
  constructor(private readonly filePath = join(homedir(), ".pi-web", "projects.json")) {}

@@ -21,9 +44,11 @@ export class ProjectStore {
    const existing = data.projects.find((p) => p.path === path);
    if (existing) return existing;

+    const trimmedName = input.name?.trim();
+    const leafName = path.split("/").filter((part) => part !== "").at(-1);
    const project: Project = {
      id: randomUUID(),
-      name: input.name?.trim() || path.split("/").filter(Boolean).at(-1) || path,
+      name: trimmedName !== undefined && trimmedName !== "" ? trimmedName : leafName ?? path,
      path,
      createdAt: new Date().toISOString(),
    };
@@ -38,9 +63,10 @@ export class ProjectStore {

  private async read(): Promise<ProjectFile> {
    try {
-      return JSON.parse(await readFile(this.filePath, "utf8")) as ProjectFile;
-    } catch (error: any) {
-      if (error?.code === "ENOENT") return { projects: [] };
+      const value: unknown = JSON.parse(await readFile(this.filePath, "utf8"));
+      return parseProjectFile(value);
+    } catch (error: unknown) {
+      if (isNodeErrorWithCode(error, "ENOENT")) return { projects: [] };
      throw error;
    }
  }
@@ -26,6 +26,12 @@ export interface ClientSession {
  firstMessage: string;
 }

+export interface ClientMessagePage {
+  messages: unknown[];
+  start: number;
+  total: number;
+}
+
 export interface ClientSessionStatus {
  sessionId: string;
  model?: { provider?: string; id?: string; name?: string; contextWindow?: number; reasoning?: unknown };
@@ -14,15 +14,18 @@ export class WorkspaceService {
    const worktrees = await discoverGitWorktrees(project.path);
    if (worktrees.length === 0) return [this.single(project)];

-    return worktrees.map((worktree) => ({
-      id: idFor(`${project.id}:${worktree.path}`),
-      projectId: project.id,
-      path: worktree.path,
-      label: worktree.branch || (worktree.detached ? "detached" : worktree.path.split("/").filter(Boolean).at(-1) || worktree.path),
-      branch: worktree.branch,
-      isMain: worktree.path === project.path,
-      isGitWorktree: true,
-    }));
+    return worktrees.map((worktree) => {
+      const leafName = worktree.path.split("/").filter((part) => part !== "").at(-1);
+      return {
+        id: idFor(`${project.id}:${worktree.path}`),
+        projectId: project.id,
+        path: worktree.path,
+        label: worktree.branch ?? (worktree.detached === true ? "detached" : leafName ?? worktree.path),
+        ...(worktree.branch === undefined ? {} : { branch: worktree.branch }),
+        isMain: worktree.path === project.path,
+        isGitWorktree: true,
+      };
+    });
  }

  private single(project: Project): Workspace {
@@ -4,6 +4,15 @@
    "module": "ESNext",
    "moduleResolution": "Bundler",
    "strict": true,
+    "noUncheckedIndexedAccess": true,
+    "exactOptionalPropertyTypes": true,
+    "noImplicitOverride": true,
+    "noPropertyAccessFromIndexSignature": true,
+    "noImplicitReturns": true,
+    "noFallthroughCasesInSwitch": true,
+    "forceConsistentCasingInFileNames": true,
+    "allowUnreachableCode": false,
+    "allowUnusedLabels": false,
    "noEmit": true,
    "skipLibCheck": true,
    "experimentalDecorators": true,