feat(FN-2944): merge fusion/fn-2944

- test(FN-2944): cover already checked out worktree conflict recovery
- fix(FN-2944): recognize git already checked out worktree conflict
- fix(engine): auto-recover from squash-merge orphan rebase failures

Fusion-Task-Id: FN-2944

packages/core/src/__tests__/setup-test-isolation.ts

@@ -14,3 +14,11 @@ import { join } from "node:path";
 
 const tempHome = mkdtempSync(join(tmpdir(), "fn-test-home-"));
 process.env.HOME = tempHome;
+process.env.USERPROFILE = tempHome;
+if (process.platform === "win32") {
+  const match = tempHome.match(/^([A-Za-z]:)(.*)$/);
+  if (match) {
+    process.env.HOMEDRIVE = match[1];
+    process.env.HOMEPATH = match[2] || "\\";
+  }
+}

packages/core/src/global-settings.ts

@@ -20,19 +20,23 @@ import { existsSync, mkdirSync, renameSync } from "node:fs";
 import type { GlobalSettings } from "./types.js";
 import { DEFAULT_GLOBAL_SETTINGS } from "./types.js";
 
+function getHomeDir(): string {
+  return process.env.HOME || process.env.USERPROFILE || homedir();
+}
+
 /** Legacy directory for global settings (original name before rename to `.fusion`). */
 export function legacyGlobalDir(): string {
-  return join(homedir(), ".pi", "fusion");
+  return join(getHomeDir(), ".pi", "fusion");
 }
 
 /** Legacy directory for global settings from the earliest fn version (`.pi/kb`). */
 export function legacyGlobalDirOriginal(): string {
-  return join(homedir(), ".pi", "kb");
+  return join(getHomeDir(), ".pi", "kb");
 }
 
 /** Default directory for global fusion settings: `~/.fusion/` */
 export function defaultGlobalDir(): string {
-  return join(homedir(), ".fusion");
+  return join(getHomeDir(), ".fusion");
 }
 
 /**

packages/core/src/migration.ts

@@ -16,6 +16,10 @@ import { isAbsolute, join, resolve, basename, dirname } from "node:path";
 import type { CentralCore } from "./central-core.js";
 import { CentralCore as CentralCoreClass } from "./central-core.js";
 
+function getHomeDir(): string {
+  return process.env.HOME || process.env.USERPROFILE || homedir();
+}
+
 /**
  * Check whether `<dir>/<folderName>/<dbName>` exists as a non-empty regular file.
  * Used to decide if a directory contains a current (.fusion/fusion.db) project database.
@@ -192,7 +196,7 @@ export class FirstRunDetector {
     const visited = new Set<string>();
 
     let current = resolve(startDir);
-    const home = homedir();
+    const home = getHomeDir();
     const root = dirname(current) === current ? current : "/"; // Handle Windows vs Unix root
     // Also stop at the OS temp directory — it is a shared system boundary and
     // should never itself host a project; stopping here prevents the walk from
@@ -299,7 +303,7 @@ export class FirstRunDetector {
   }
 
   private getDefaultGlobalDir(): string {
-    return join(homedir(), ".pi", "kb");
+    return join(getHomeDir(), ".pi", "kb");
   }
 }