diff --git a/src/cli.tsx b/src/cli.tsx
index 26e383c..daa4783 100644
--- a/src/cli.tsx
+++ b/src/cli.tsx
@@ -170,6 +170,14 @@ const promptHistory = await store.loadHistory();
 
 const installedPlugins = has('--no-plugins') ? { plugins: [], errors: [] } : await registry.loadInstalledPlugins();
 
+// Full ignore-aware file list injected into the system prompt at boot.
+// Same walk as `@` completion (5000 cap, .gitignore + .shiroignore, skips .git/node_modules),
+// so a filtered repo stays small even though it's "full".
+let workspaceFiles: string[] = [];
+try {
+  for await (const rel of walk({ limit: 5000 })) workspaceFiles.push(rel);
+} catch {}
+
 /** Installed entries, as `kind:name`, so the registry list can mark what is already here. */
 async function installedNames(): Promise<Set<string>> {
   const names = new Set<string>();
@@ -321,6 +329,7 @@ const session = new Session({
   skills,
   plugins,
   agent: agentVariant,
+  ...(workspaceFiles.length > 0 ? { workspaceFiles } : {}),
   ...(cfg.toolSets ? { toolSets: cfg.toolSets } : {}),
   ...(cfg.permission ? { permissions: cfg.permission } : {}),
   // Headless has no one to answer, so the tool is withheld rather than left to hang.
@@ -343,6 +352,7 @@ const session = new Session({
             model: languageModel ?? unconfiguredModel,
             subagentModel,
             subagentModelId: cfg.subagentModel,
+            ...(workspaceFiles.length > 0 ? { workspaceFiles } : {}),
             onUsage: (u) => recordSubagent(u),
             ...(headless ? {} : { report: subagents.emit }),
             // A worker's writes go through the parent's rules and the parent's
diff --git a/src/prompt.ts b/src/prompt.ts
index 1e9ba23..cb946d7 100644
--- a/src/prompt.ts
+++ b/src/prompt.ts
@@ -20,6 +20,8 @@ export type PromptParts = {
   canAsk?: boolean;
   /** MCP server names — listed by name only so their schemas cost nothing until mcp_call. */
   mcpServers?: readonly string[];
+  /** Ignore-aware workspace file list injected at boot (gitignore-respected, capped). */
+  workspaceFiles?: readonly string[];
 };
 
 type ToolDoc = { name: string; line: string };
@@ -215,7 +217,7 @@ export function systemPrompt(parts: PromptParts): string {
 Environment
 - Workspace root: ${cwd}
 - Platform: ${process.platform}
-- Paths are resolved inside the workspace. Anything outside it is refused.
+- Paths are resolved inside the workspace. Anything outside it is refused.${parts.workspaceFiles && parts.workspaceFiles.length > 0 ? `\n- Workspace files (${parts.workspaceFiles.length}, gitignore-respected, capped 5000):\n${parts.workspaceFiles.join('\n')}` : ''}
 
 Tools available to you now
 ${renderTools(toolNames)}${mcpServers.length > 0 ? `\n\nMCP servers (${mcpServers.length}): ${mcpServers.join(', ')} — tools are NOT in the prompt. Use mcp_list to see what each exposes, mcp_inspect for a tool\'s schema, then mcp_call to run it. Each mcp_call needs approval like a built-in.` : ''}
diff --git a/src/session.ts b/src/session.ts
index 0aa2dab..492b63b 100644
--- a/src/session.ts
+++ b/src/session.ts
@@ -98,6 +98,8 @@ export type SessionOptions = {
   learnerModel?: LanguageModel;
   /** Emit learner notices to the UI. */
   onNotice?: (text: string) => void;
+  /** Ignore-aware file list injected into the system prompt at boot; gitignore-respected. */
+  workspaceFiles?: readonly string[];
   /** Disable background auto-learn (tests). */
   disableAutoLearn?: boolean;
 };
@@ -487,6 +489,7 @@ export class Session {
       availableTools: this.activeTools(),
       canAsk: this.opts.ask !== undefined && this.activeTools().includes('ask'),
       ...(this.mcpServerNamesForPrompt() ? { mcpServers: this.mcpServerNamesForPrompt() } : {}),
+      ...(this.opts.workspaceFiles && this.opts.workspaceFiles.length > 0 ? { workspaceFiles: this.opts.workspaceFiles } : {}),
     });
   }
 
diff --git a/src/subagent.ts b/src/subagent.ts
index 1ee87e9..c66c4db 100644
--- a/src/subagent.ts
+++ b/src/subagent.ts
@@ -103,6 +103,11 @@ Rules:
   it said, and anything you could not finish. The parent cannot see your transcript.`,
 };
 
+function withWorkspaceFiles(base: string, workspaceFiles?: readonly string[]): string {
+  if (!workspaceFiles || workspaceFiles.length === 0) return base;
+  return `${base}\n\nWorkspace files (${workspaceFiles.length}, gitignore-respected, capped 5000):\n${workspaceFiles.join('\n')}`;
+}
+
 /** One line of detail for the panel: the argument that identifies the call. */
 const summarize = (input: unknown): string => {
   if (input === null || typeof input !== 'object') return String(input);
@@ -148,6 +153,7 @@ async function runOne(
     model: LanguageModel;
     subagentModel?: LanguageModel;
     cwd?: string;
+    workspaceFiles?: readonly string[];
     maxSteps?: number;
     report?: SubagentReporter;
     approve?: SubagentApproval;
@@ -170,7 +176,7 @@ async function runOne(
     const model = flavour === 'explore' ? (opts.subagentModel ?? opts.model) : opts.model;
     const result = streamText({
       model,
-      system: PROMPTS[flavour](opts.cwd ?? process.cwd()),
+      system: withWorkspaceFiles(PROMPTS[flavour](opts.cwd ?? process.cwd()), opts.workspaceFiles),
       messages: [{ role: 'user', content: spec.prompt }],
       tools: TOOLS[flavour],
       stopWhen: isStepCount(opts.maxSteps ?? 20),
@@ -236,6 +242,7 @@ export function createTaskTool(opts: {
   /** Its id, so the parent can price the subagent's spend separately. */
   subagentModelId?: string;
   cwd?: string;
+  workspaceFiles?: readonly string[];
   maxSteps?: number;
   report?: SubagentReporter;
   /** Parent-owned approval for a worker's gated calls. Omit to disable `worker`. */
@@ -304,6 +311,7 @@ export function createTaskTool(opts: {
           model: opts.model,
           subagentModel: opts.subagentModel,
           cwd: opts.cwd,
+          workspaceFiles: opts.workspaceFiles,
           maxSteps: opts.maxSteps,
           report: opts.report,
           approve: opts.approve,
diff --git a/test/prompt-workspace.test.ts b/test/prompt-workspace.test.ts
new file mode 100644
index 0000000..26ac393
--- /dev/null
+++ b/test/prompt-workspace.test.ts
@@ -0,0 +1,19 @@
+import { expect, test } from 'bun:test';
+import { systemPrompt } from '../src/prompt';
+
+test('workspaceFiles are injected gitignore-style when provided', () => {
+  const prompt = systemPrompt({ cwd: '/repo', workspaceFiles: ['src/app.ts', 'README.md'] });
+  expect(prompt).toContain('Workspace files (2, gitignore-respected');
+  expect(prompt).toContain('src/app.ts');
+  expect(prompt).toContain('README.md');
+});
+
+test('workspaceFiles omitted when empty', () => {
+  const prompt = systemPrompt({ cwd: '/repo', workspaceFiles: [] });
+  expect(prompt).not.toContain('Workspace files');
+});
+
+test('workspaceFiles undefined leaves prompt unchanged', () => {
+  const prompt = systemPrompt({ cwd: '/repo' });
+  expect(prompt).not.toContain('Workspace files');
+});