chore: auto-commit before switching to gsd/M002/S01

.claude/worktrees/agent-aa26d13d

@@ -1 +0,0 @@
-Subproject commit afcbdfa956c83b3bb6f5476bb02437d9edeeda10

.claude/worktrees/agent-aca4a27a

@@ -1 +0,0 @@
-Subproject commit 00d9aed6b03298b902452da0a29d9a8ff7f7f7c7

.claude/worktrees/agent-af52432f

@@ -1 +0,0 @@
-Subproject commit 5f7e040254970b356e4e70d9d1a307fe07e2209a

src/resources/extensions/gsd/auto.ts

@@ -56,7 +56,7 @@ import {
 } from "./metrics.js";
 import { join } from "node:path";
 import { readdirSync, readFileSync, existsSync, mkdirSync, writeFileSync } from "node:fs";
-import { execSync } from "node:child_process";
+import { execSync, execFileSync } from "node:child_process";
 import {
   autoCommitCurrentBranch,
   ensureSliceBranch,
@@ -373,7 +373,8 @@ export async function startAuto(
   try {
     execSync("git rev-parse --git-dir", { cwd: base, stdio: "pipe" });
   } catch {
-    execSync("git init", { cwd: base, stdio: "pipe" });
+    const mainBranch = loadEffectiveGSDPreferences()?.preferences?.git?.main_branch || "main";
+    execFileSync("git", ["init", "-b", mainBranch], { cwd: base, stdio: "pipe" });
   }
 
   // Ensure .gitignore has baseline patterns

src/resources/extensions/gsd/docs/preferences-reference.md

@@ -47,6 +47,7 @@ Full documentation for `~/.gsd/preferences.md` (global) and `.gsd/preferences.md
   - `snapshots`: boolean — create snapshot commits (WIP saves) during long-running tasks. Default: `false`.
   - `pre_merge_check`: boolean or `"auto"` — run pre-merge checks before merging a slice branch. `true` always runs, `false` never runs, `"auto"` runs when CI is detected. Default: `false`.
   - `commit_type`: string — override the conventional commit type prefix. Must be one of: `feat`, `fix`, `refactor`, `docs`, `test`, `chore`, `perf`, `ci`, `build`, `style`. Default: inferred from diff content.
+  - `main_branch`: string — the primary branch name for new git repos (e.g., `"main"`, `"master"`, `"trunk"`). Also used by `getMainBranch()` as the preferred branch when auto-detection is ambiguous. Default: `"main"`.
 
 ---
 

src/resources/extensions/gsd/git-service.ts

@@ -27,8 +27,11 @@ export interface GitPreferences {
   snapshots?: boolean;
   pre_merge_check?: boolean | string;
   commit_type?: string;
+  main_branch?: string;
 }
 
+export const VALID_BRANCH_NAME = /^[a-zA-Z0-9_\-\/.]+$/;
+
 export interface CommitOptions {
   message: string;
   allowEmpty?: boolean;
@@ -192,6 +195,12 @@ export class GitServiceImpl {
       return this.git(["branch", "--show-current"]);
     }
 
+    // Explicit preference takes priority over auto-detection
+    const configured = this.prefs.main_branch;
+    if (configured && VALID_BRANCH_NAME.test(configured)) {
+      return configured;
+    }
+
     const symbolic = this.git(["symbolic-ref", "refs/remotes/origin/HEAD"], { allowFailure: true });
     if (symbolic) {
       const match = symbolic.match(/refs\/remotes\/origin\/(.+)$/);

src/resources/extensions/gsd/gitignore.ts

@@ -145,6 +145,7 @@ See \`~/.gsd/agent/extensions/gsd/docs/preferences-reference.md\` for full field
 - \`models\`: Model preferences for specific task types
 - \`skill_discovery\`: Automatic skill detection preferences
 - \`auto_supervisor\`: Supervision and gating rules for autonomous modes
+- \`git\`: Git preferences — \`main_branch\` (default branch name for new repos, e.g., "main", "master", "trunk"), \`auto_push\`, \`snapshots\`, etc.
 
 ## Examples
 

src/resources/extensions/gsd/guided-flow.ts

@@ -20,8 +20,9 @@ import {
 } from "./paths.js";
 import { join } from "node:path";
 import { readFileSync, existsSync, mkdirSync, readdirSync } from "node:fs";
-import { execSync } from "node:child_process";
+import { execSync, execFileSync } from "node:child_process";
 import { ensureGitignore, ensurePreferences } from "./gitignore.js";
+import { loadEffectiveGSDPreferences } from "./preferences.js";
 
 // ─── Auto-start after discuss ─────────────────────────────────────────────────
 
@@ -444,7 +445,8 @@ export async function showSmartEntry(
   try {
     execSync("git rev-parse --git-dir", { cwd: basePath, stdio: "pipe" });
   } catch {
-    execSync("git init", { cwd: basePath, stdio: "pipe" });
+    const mainBranch = loadEffectiveGSDPreferences()?.preferences?.git?.main_branch || "main";
+    execFileSync("git", ["init", "-b", mainBranch], { cwd: basePath, stdio: "pipe" });
   }
 
   // ── Ensure .gitignore has baseline patterns ──────────────────────────

src/resources/extensions/gsd/preferences.ts

@@ -3,6 +3,7 @@ import { homedir } from "node:os";
 import { isAbsolute, join } from "node:path";
 import { getAgentDir } from "@mariozechner/pi-coding-agent";
 import type { GitPreferences } from "./git-service.ts";
+import { VALID_BRANCH_NAME } from "./git-service.ts";
 
 const GLOBAL_PREFERENCES_PATH = join(homedir(), ".gsd", "preferences.md");
 const LEGACY_GLOBAL_PREFERENCES_PATH = join(homedir(), ".pi", "agent", "gsd-preferences.md");
@@ -639,6 +640,13 @@ function validatePreferences(preferences: GSDPreferences): {
         errors.push(`git.commit_type must be one of: feat, fix, refactor, docs, test, chore, perf, ci, build, style`);
       }
     }
+    if (g.main_branch !== undefined) {
+      if (typeof g.main_branch === "string" && g.main_branch.trim() !== "" && VALID_BRANCH_NAME.test(g.main_branch)) {
+        git.main_branch = g.main_branch;
+      } else {
+        errors.push("git.main_branch must be a valid branch name (alphanumeric, _, -, /, .)");
+      }
+    }
 
     if (Object.keys(git).length > 0) {
       validated.git = git as GitPreferences;