diff --git a/.trellis/spec/backend/quality-guidelines.md b/.trellis/spec/backend/quality-guidelines.md
index d3cca2e..a90219d 100644
--- a/.trellis/spec/backend/quality-guidelines.md
+++ b/.trellis/spec/backend/quality-guidelines.md
@@ -47,6 +47,18 @@ the chosen IDEA/Tomcat project structure. Until then, documentation-only
 changes should run Trellis validation, Python compile checks for Trellis
 scripts when relevant, and placeholder scans for scaffold markers.
 
+For this workspace, Maven is available at:
+
+```bash
+/home/sjy/.sdkman/candidates/maven/current/bin/mvn
+```
+
+Use the explicit path when `mvn` is not on `PATH`:
+
+```bash
+/home/sjy/.sdkman/candidates/maven/current/bin/mvn clean package
+```
+
 ---
 
 ## Review Checklist
diff --git a/.trellis/tasks/04-27-core-function-gap-check/prd.md b/.trellis/tasks/04-27-core-function-gap-check/prd.md
index 04d7d12..65efc1e 100644
--- a/.trellis/tasks/04-27-core-function-gap-check/prd.md
+++ b/.trellis/tasks/04-27-core-function-gap-check/prd.md
@@ -16,7 +16,9 @@ without broad redesign.
   reader loan history, reports, administrator user management, and system-log
   viewing.
 * Existing lightweight checks pass with `javac -Xlint:all` for non-Servlet
-  layers and all service check mains. Maven is unavailable in this environment.
+  layers and all service check mains.
+* Maven is available in this workspace at
+  `/home/sjy/.sdkman/candidates/maven/current/bin/mvn`.
 * The clearest missing core requirement is book category maintenance. The
   schema and selectors already have `book_categories`, but there is no route,
   controller, JSP, DAO/service mutation API, or test coverage for maintaining
@@ -48,8 +50,8 @@ without broad redesign.
 * [x] Book forms/search continue to load categories from the shared DAO/service
   path.
 * [x] JSPs do not contain SQL/JDBC/scriptlet logic.
-* [x] Existing lightweight checks pass; Maven limitation is documented if still
-  unavailable.
+* [x] Existing lightweight checks pass and Maven package succeeds through the
+  workspace Maven path.
 
 ## Definition of Done
 
@@ -82,12 +84,14 @@ without broad redesign.
   `BookServiceCheck`.
 * Initial verification before implementation:
   `javac -Xlint:all` over non-Servlet app layers and tests passed; all eight
-  service check mains passed. `mvn` is not installed.
+  service check mains passed.
 * Final verification after implementation:
   `javac -Xlint:all` over non-Servlet app layers and tests passed;
   `PermissionPolicyCheck`, `AuthServiceCheck`, `BookServiceCheck`,
   `ReaderServiceCheck`, `BorrowingServiceCheck`, `ReportServiceCheck`,
   `UserAccountServiceCheck`, and `SystemLogServiceCheck` passed;
   JSP/static scriptlet and SQL/JDBC scan returned no matches;
-  `git diff --check` passed; `mvn clean package` remains blocked because `mvn`
-  is not installed.
+  `git diff --check` passed.
+* Maven verification on 2026-04-27:
+  `/home/sjy/.sdkman/candidates/maven/current/bin/mvn clean package` passed and
+  produced `target/library-management.war`.