diff --git a/src/resources/extensions/sf/code-intelligence.ts b/src/resources/extensions/sf/code-intelligence.ts
index aab552625..e92e2c676 100644
--- a/src/resources/extensions/sf/code-intelligence.ts
+++ b/src/resources/extensions/sf/code-intelligence.ts
@@ -145,12 +145,12 @@ const DEFAULT_SIFT_WARMUP_HARD_TIMEOUT_SEC = 30;
 const SIFT_WARMUP_KILL_GRACE_SEC = 10;
 
 function resolveSiftWarmupRuntimeDirs(projectRoot: string): {
-	cacheHome: string;
+	searchCache: string;
 	tmpDir: string;
 } {
 	const runtimeRoot = join(projectRoot, ".sf", "runtime", "sift");
 	return {
-		cacheHome: join(runtimeRoot, "xdg-cache"),
+		searchCache: join(runtimeRoot, "search-cache"),
 		tmpDir: join(runtimeRoot, "tmp"),
 	};
 }
@@ -162,7 +162,7 @@ function buildSiftWarmupEnv(
 	const dirs = resolveSiftWarmupRuntimeDirs(projectRoot);
 	return {
 		...env,
-		XDG_CACHE_HOME: dirs.cacheHome,
+		SIFT_SEARCH_CACHE: dirs.searchCache,
 		TMPDIR: dirs.tmpDir,
 	};
 }
@@ -513,7 +513,7 @@ export function ensureSiftIndexWarmup(
 	try {
 		const runtimeDirs = resolveSiftWarmupRuntimeDirs(projectRoot);
 		mkdirSync(join(projectRoot, ".sf", "runtime"), { recursive: true });
-		mkdirSync(runtimeDirs.cacheHome, { recursive: true });
+		mkdirSync(runtimeDirs.searchCache, { recursive: true });
 		mkdirSync(runtimeDirs.tmpDir, { recursive: true });
 		const childEnv = buildSiftWarmupEnv(projectRoot, env);
 		writeFileSync(
@@ -527,7 +527,7 @@ export function ensureSiftIndexWarmup(
 					args,
 					siftBinary: detection.binaryPath,
 					hardTimeoutSec: wrapper?.timeoutSec ?? null,
-					cacheHome: runtimeDirs.cacheHome,
+					searchCache: runtimeDirs.searchCache,
 					tmpDir: runtimeDirs.tmpDir,
 				},
 				null,
@@ -820,7 +820,7 @@ function buildSiftContextLines(
 				'`--strategy path-hybrid` for path-heavy queries, and `sift search <path> --agent "<task>"` for bounded planner-driven exploration.',
 		);
 		lines.push(
-			"- SF runs Sift warmup with project-scoped cache/temp directories under `.sf/runtime/sift/`; " +
+			"- SF runs Sift warmup with a project-scoped `SIFT_SEARCH_CACHE` under `.sf/runtime/sift/` while leaving model cache shared; " +
 				"if the CLI is missing or fails, continue with `.sf/CODEBASE.md`, native `grep`/`find`/`ls`, `lsp`, and scout.",
 		);
 	} else {
@@ -989,7 +989,7 @@ export function formatSiftStatus(
 		'When configured, agents should use `sift search --json <path> "<query>"`; `page-index-hybrid` is the strongest direct-search preset and `path-hybrid` is best for path-heavy queries.',
 	);
 	lines.push(
-		"SF runs Sift warmup with project-scoped cache/temp directories under .sf/runtime/sift/.",
+		"SF runs Sift warmup with a project-scoped SIFT_SEARCH_CACHE under .sf/runtime/sift/ while leaving model cache shared.",
 	);
 	return lines.join("\n");
 }
diff --git a/src/resources/extensions/sf/tests/code-intelligence.test.ts b/src/resources/extensions/sf/tests/code-intelligence.test.ts
index 6e64a6cdb..d3babc31d 100644
--- a/src/resources/extensions/sf/tests/code-intelligence.test.ts
+++ b/src/resources/extensions/sf/tests/code-intelligence.test.ts
@@ -529,8 +529,8 @@ test("ensureSiftIndexWarmup defaults optional warmup hard cap to 30 seconds", ()
 		]);
 		assert.match(result.reason, /hard cap 30s/);
 		assert.equal(
-			calls[0].options?.env?.XDG_CACHE_HOME,
-			join(projectRoot, ".sf", "runtime", "sift", "xdg-cache"),
+			calls[0].options?.env?.SIFT_SEARCH_CACHE,
+			join(projectRoot, ".sf", "runtime", "sift", "search-cache"),
 		);
 		assert.equal(
 			calls[0].options?.env?.TMPDIR,
@@ -543,8 +543,8 @@ test("ensureSiftIndexWarmup defaults optional warmup hard cap to 30 seconds", ()
 			),
 		);
 		assert.equal(
-			marker.cacheHome,
-			join(projectRoot, ".sf", "runtime", "sift", "xdg-cache"),
+			marker.searchCache,
+			join(projectRoot, ".sf", "runtime", "sift", "search-cache"),
 		);
 		assert.equal(
 			marker.tmpDir,