fix(completion): restore .zshrc byte for byte on zsh uninstall (#2016)

removeZshrcConfig stripped every blank line at the top of .zshrc after
removing the OpenSpec block, so a file that started with blank lines
lost them in an install/uninstall round trip, even when the user had
moved the block further down. Drop only the separator line install
added, and only when the block sits at the top, as #1872 did for bash.

Closes #2015

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

.changeset/zsh-completion-uninstall-restores-zshrc.md

@@ -0,0 +1,5 @@
+---
+'@fission-ai/openspec': patch
+---
+
+Make `openspec completion uninstall zsh` hand `.zshrc` back exactly as `completion install zsh` found it. Uninstall stripped every blank line at the top of the file, so a `.zshrc` that started with blank lines lost them after an install/uninstall round trip, even when the OpenSpec block had been moved further down. Uninstall now drops only the separator line install added, and only when the block sits at the top of the file, matching the bash installer.

src/core/completions/installers/zsh-installer.ts

@@ -220,8 +220,10 @@ export class ZshInstaller {
       // Remove lines between markers (inclusive)
       lines.splice(startIndex, endIndex - startIndex + 1);
 
-      // Remove trailing empty lines at the start if the markers were at the top
-      while (lines.length > 0 && lines[0].trim() === '') {
+      // Install puts the block at the top of the file followed by one blank
+      // separator line; drop that line too so the file reads as it did before.
+      // Everything else, including blank lines the user had at the top, is left as is.
+      if (startIndex === 0 && lines.length > 0 && lines[0].trim() === '') {
         lines.shift();
       }
 

test/core/completions/installers/zsh-installer.round-trip.test.ts

@@ -0,0 +1,76 @@
+import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import { promises as fs } from 'fs';
+import path from 'path';
+import os from 'os';
+import { ZshInstaller } from '../../../../src/core/completions/installers/zsh-installer.js';
+
+/**
+ * Installing and then uninstalling zsh completions must hand the user's .zshrc
+ * back byte for byte, as bash does since #1872. Uninstall used to strip every
+ * blank line at the top of the file, so a .zshrc that started with blank lines
+ * lost them, even when the OpenSpec block was not at the top.
+ */
+describe('ZshInstaller .zshrc round trip', () => {
+  let homeDir: string;
+  let zshrcPath: string;
+  let completionsDir: string;
+  let installer: ZshInstaller;
+  let savedZsh: string | undefined;
+
+  beforeEach(async () => {
+    homeDir = await fs.mkdtemp(path.join(os.tmpdir(), 'openspec-zshrc-round-trip-'));
+    zshrcPath = path.join(homeDir, '.zshrc');
+    completionsDir = path.join(homeDir, '.zsh', 'completions');
+    installer = new ZshInstaller(homeDir);
+    // Standard zsh only: Oh My Zsh does not use the .zshrc block.
+    savedZsh = process.env.ZSH;
+    delete process.env.ZSH;
+  });
+
+  afterEach(async () => {
+    if (savedZsh === undefined) delete process.env.ZSH;
+    else process.env.ZSH = savedZsh;
+    await fs.rm(homeDir, { recursive: true, force: true });
+  });
+
+  /** Writes `original`, adds the OpenSpec block, removes it, and returns the file. */
+  async function roundTrip(original: string): Promise<string> {
+    await fs.writeFile(zshrcPath, original);
+    expect(await installer.configureZshrc(completionsDir)).toBe(true);
+    expect(await fs.readFile(zshrcPath, 'utf-8')).toContain('# OPENSPEC:START');
+    expect(await installer.removeZshrcConfig()).toBe(true);
+    return fs.readFile(zshrcPath, 'utf-8');
+  }
+
+  it.each([
+    ['a file ending in a newline', 'export PATH="$HOME/bin:$PATH"\nalias ll="ls -la"\n'],
+    ['a file with no final newline', 'export PATH="$HOME/bin:$PATH"\nalias ll="ls -la"'],
+    ['an empty file', ''],
+    ['a file ending in blank lines', 'alias ll="ls -la"\n\n\n'],
+    ['a file starting with blank lines', '\n\nalias ll="ls -la"\n'],
+    ['a file with CRLF line endings', 'export PATH="$HOME/bin:$PATH"\r\nalias ll="ls -la"\r\n'],
+  ])('restores %s byte for byte', async (_label, original) => {
+    expect(await roundTrip(original)).toBe(original);
+  });
+
+  it('keeps leading blank lines when the user moved the block further down', async () => {
+    await fs.writeFile(
+      zshrcPath,
+      ['', 'export PATH="$HOME/bin:$PATH"', '# OPENSPEC:START', '# OpenSpec shell completions configuration', '# OPENSPEC:END', 'alias ll="ls -la"', ''].join('\n')
+    );
+
+    expect(await installer.removeZshrcConfig()).toBe(true);
+    expect(await fs.readFile(zshrcPath, 'utf-8')).toBe('\nexport PATH="$HOME/bin:$PATH"\nalias ll="ls -la"\n');
+  });
+
+  it('keeps user content written directly after a top-of-file block', async () => {
+    // The user deleted the separator line, so nothing blank follows the block.
+    await fs.writeFile(
+      zshrcPath,
+      '# OPENSPEC:START\n# OpenSpec shell completions configuration\n# OPENSPEC:END\nalias ll="ls -la"\n\nexport EDITOR=vim\n'
+    );
+
+    expect(await installer.removeZshrcConfig()).toBe(true);
+    expect(await fs.readFile(zshrcPath, 'utf-8')).toBe('alias ll="ls -la"\n\nexport EDITOR=vim\n');
+  });
+});