diff --git a/crates/bashkit/src/interpreter/mod.rs b/crates/bashkit/src/interpreter/mod.rs
index 5e547381..77d04f92 100644
--- a/crates/bashkit/src/interpreter/mod.rs
+++ b/crates/bashkit/src/interpreter/mod.rs
@@ -3860,6 +3860,8 @@ impl Interpreter {
         let mut is_assoc = false;
         let mut is_integer = false;
         let mut is_nameref = false;
+        let mut is_lowercase = false;
+        let mut is_uppercase = false;
         let mut names: Vec<&str> = Vec::new();
 
         for arg in args {
@@ -3873,7 +3875,9 @@ impl Interpreter {
                         'i' => is_integer = true,
                         'A' => is_assoc = true,
                         'n' => is_nameref = true,
-                        'g' | 'l' | 'u' | 't' | 'f' | 'F' => {} // ignored
+                        'l' => is_lowercase = true,
+                        'u' => is_uppercase = true,
+                        'g' | 't' | 'f' | 'F' => {} // ignored
                         _ => {}
                     }
                 }
@@ -4027,10 +4031,28 @@ impl Interpreter {
                     self.variables
                         .insert(var_name.to_string(), int_val.to_string());
                 } else {
-                    self.variables
-                        .insert(var_name.to_string(), value.to_string());
+                    // Apply case conversion attributes
+                    let final_value = if is_lowercase {
+                        value.to_lowercase()
+                    } else if is_uppercase {
+                        value.to_uppercase()
+                    } else {
+                        value.to_string()
+                    };
+                    self.variables.insert(var_name.to_string(), final_value);
                 }
 
+                // Set case conversion attribute markers
+                if is_lowercase {
+                    self.variables
+                        .insert(format!("_LOWER_{}", var_name), "1".to_string());
+                    self.variables.remove(&format!("_UPPER_{}", var_name));
+                }
+                if is_uppercase {
+                    self.variables
+                        .insert(format!("_UPPER_{}", var_name), "1".to_string());
+                    self.variables.remove(&format!("_LOWER_{}", var_name));
+                }
                 if is_readonly {
                     self.variables
                         .insert(format!("_READONLY_{}", var_name), "1".to_string());
@@ -4055,6 +4077,17 @@ impl Interpreter {
                 } else if !self.variables.contains_key(name.as_str()) {
                     self.variables.insert(name.to_string(), String::new());
                 }
+                // Set case conversion attribute markers
+                if is_lowercase {
+                    self.variables
+                        .insert(format!("_LOWER_{}", name), "1".to_string());
+                    self.variables.remove(&format!("_UPPER_{}", name));
+                }
+                if is_uppercase {
+                    self.variables
+                        .insert(format!("_UPPER_{}", name), "1".to_string());
+                    self.variables.remove(&format!("_LOWER_{}", name));
+                }
                 if is_readonly {
                     self.variables
                         .insert(format!("_READONLY_{}", name), "1".to_string());
@@ -5627,6 +5660,24 @@ impl Interpreter {
     fn set_variable(&mut self, name: String, value: String) {
         // Resolve nameref: if `name` is a nameref, assign to the target instead
         let resolved = self.resolve_nameref(&name).to_string();
+        // Apply case conversion attributes (declare -l / declare -u)
+        let value = if self
+            .variables
+            .get(&format!("_LOWER_{}", resolved))
+            .map(|v| v == "1")
+            .unwrap_or(false)
+        {
+            value.to_lowercase()
+        } else if self
+            .variables
+            .get(&format!("_UPPER_{}", resolved))
+            .map(|v| v == "1")
+            .unwrap_or(false)
+        {
+            value.to_uppercase()
+        } else {
+            value
+        };
         for frame in self.call_stack.iter_mut().rev() {
             if let std::collections::hash_map::Entry::Occupied(mut e) =
                 frame.locals.entry(resolved.clone())
diff --git a/crates/bashkit/tests/spec_cases/bash/declare.test.sh b/crates/bashkit/tests/spec_cases/bash/declare.test.sh
index e11b1993..bccb9d7c 100644
--- a/crates/bashkit/tests/spec_cases/bash/declare.test.sh
+++ b/crates/bashkit/tests/spec_cases/bash/declare.test.sh
@@ -143,3 +143,68 @@ echo "$ref"
 first
 second
 ### end
+
+### declare_lowercase
+# declare -l converts value to lowercase
+declare -l x=HELLO
+echo "$x"
+### expect
+hello
+### end
+
+### declare_uppercase
+# declare -u converts value to uppercase
+declare -u x=hello
+echo "$x"
+### expect
+HELLO
+### end
+
+### declare_lowercase_subsequent
+# declare -l applies to subsequent assignments
+declare -l x
+x=WORLD
+echo "$x"
+### expect
+world
+### end
+
+### declare_uppercase_subsequent
+# declare -u applies to subsequent assignments
+declare -u x
+x=world
+echo "$x"
+### expect
+WORLD
+### end
+
+### declare_lowercase_mixed
+# declare -l handles mixed case
+declare -l x=HeLLo_WoRLd
+echo "$x"
+### expect
+hello_world
+### end
+
+### declare_uppercase_overrides_lowercase
+# declare -u after -l overrides to uppercase
+declare -l x=Hello
+echo "$x"
+declare -u x
+x=Hello
+echo "$x"
+### expect
+hello
+HELLO
+### end
+
+### declare_case_in_function
+# declare -l works in functions
+toupper() {
+  declare -u result="$1"
+  echo "$result"
+}
+toupper "hello world"
+### expect
+HELLO WORLD
+### end
diff --git a/specs/009-implementation-status.md b/specs/009-implementation-status.md
index e3abbc56..e32e9726 100644
--- a/specs/009-implementation-status.md
+++ b/specs/009-implementation-status.md
@@ -103,17 +103,17 @@ Bashkit implements IEEE 1003.1-2024 Shell Command Language. See
 
 ## Spec Test Coverage
 
-**Total spec test cases:** 1305 (1300 pass, 5 skip)
+**Total spec test cases:** 1318 (1313 pass, 5 skip)
 
 | Category | Cases | In CI | Pass | Skip | Notes |
 |----------|-------|-------|------|------|-------|
-| Bash (core) | 893 | Yes | 888 | 5 | `bash_spec_tests` in CI |
+| Bash (core) | 900 | Yes | 895 | 5 | `bash_spec_tests` in CI |
 | AWK | 96 | Yes | 96 | 0 | loops, arrays, -v, ternary, field assign, getline, %.6g |
 | Grep | 76 | Yes | 76 | 0 | -z, -r, -a, -b, -H, -h, -f, -P, --include, --exclude, binary detect |
 | Sed | 75 | Yes | 75 | 0 | hold space, change, regex ranges, -E |
 | JQ | 114 | Yes | 114 | 0 | reduce, walk, regex funcs, --arg/--argjson, combined flags, input/inputs, env |
 | Python | 57 | Yes | 57 | 0 | embedded Python (Monty) |
-| **Total** | **1311** | **Yes** | **1306** | **5** | |
+| **Total** | **1318** | **Yes** | **1313** | **5** | |
 
 ### Bash Spec Tests Breakdown
 
@@ -160,7 +160,7 @@ Bashkit implements IEEE 1003.1-2024 Shell Command Language. See
 | variables.test.sh | 86 | includes special vars, prefix env, PIPESTATUS, trap EXIT, `${var@Q}`, `\<newline>` line continuation, PWD/HOME/USER/HOSTNAME/BASH_VERSION/SECONDS, `set -x` xtrace, `shopt` builtin, nullglob |
 | wc.test.sh | 35 | word count (5 skipped) |
 | type.test.sh | 15 | `type`, `which`, `hash` builtins |
-| declare.test.sh | 16 | `declare`/`typeset`, `-i`, `-r`, `-x`, `-a`, `-p`, `-n` nameref |
+| declare.test.sh | 23 | `declare`/`typeset`, `-i`, `-r`, `-x`, `-a`, `-p`, `-n` nameref, `-l`/`-u` case conversion |
 | ln.test.sh | 5 | `ln -s`, `-f`, symlink creation |
 | eval-bugs.test.sh | 4 | regression tests for eval/script bugs |
 | script-exec.test.sh | 10 | script execution by path, $PATH search, exit codes |
@@ -183,7 +183,7 @@ Features that may be added in the future (not intentionally excluded):
 | ~~`getopts`~~ | ~~Medium~~ | Implemented: POSIX option parsing |
 | ~~`command` builtin~~ | ~~Medium~~ | Implemented: `-v`, `-V`, bypass functions |
 | ~~`type`/`which` builtins~~ | ~~Medium~~ | Implemented: `-t`, `-a`, `-p` flags |
-| ~~`declare` builtin~~ | ~~Medium~~ | Implemented: `-i`, `-r`, `-x`, `-a`, `-p` |
+| ~~`declare` builtin~~ | ~~Medium~~ | Implemented: `-i`, `-r`, `-x`, `-a`, `-p`, `-n`, `-l`, `-u` |
 | ~~`ln` builtin~~ | ~~Medium~~ | Implemented: symbolic links (`-s`, `-f`) |
 | `alias` | Low | Interactive feature |
 | History expansion | Out of scope | Interactive only |
diff --git a/supply-chain/config.toml b/supply-chain/config.toml
index fc2868e9..fbb2fec5 100644
--- a/supply-chain/config.toml
+++ b/supply-chain/config.toml
@@ -610,6 +610,10 @@ criteria = "safe-to-deploy"
 version = "0.3.89"
 criteria = "safe-to-deploy"
 
+[[exemptions.js-sys]]
+version = "0.3.90"
+criteria = "safe-to-deploy"
+
 [[exemptions.leb128fmt]]
 version = "0.1.0"
 criteria = "safe-to-deploy"
@@ -1386,22 +1390,42 @@ criteria = "safe-to-run"
 version = "0.2.112"
 criteria = "safe-to-deploy"
 
+[[exemptions.wasm-bindgen]]
+version = "0.2.113"
+criteria = "safe-to-deploy"
+
 [[exemptions.wasm-bindgen-futures]]
 version = "0.4.62"
 criteria = "safe-to-deploy"
 
+[[exemptions.wasm-bindgen-futures]]
+version = "0.4.63"
+criteria = "safe-to-deploy"
+
 [[exemptions.wasm-bindgen-macro]]
 version = "0.2.112"
 criteria = "safe-to-deploy"
 
+[[exemptions.wasm-bindgen-macro]]
+version = "0.2.113"
+criteria = "safe-to-deploy"
+
 [[exemptions.wasm-bindgen-macro-support]]
 version = "0.2.112"
 criteria = "safe-to-deploy"
 
+[[exemptions.wasm-bindgen-macro-support]]
+version = "0.2.113"
+criteria = "safe-to-deploy"
+
 [[exemptions.wasm-bindgen-shared]]
 version = "0.2.112"
 criteria = "safe-to-deploy"
 
+[[exemptions.wasm-bindgen-shared]]
+version = "0.2.113"
+criteria = "safe-to-deploy"
+
 [[exemptions.wasm-encoder]]
 version = "0.244.0"
 criteria = "safe-to-deploy"
@@ -1422,6 +1446,10 @@ criteria = "safe-to-deploy"
 version = "0.3.89"
 criteria = "safe-to-deploy"
 
+[[exemptions.web-sys]]
+version = "0.3.90"
+criteria = "safe-to-deploy"
+
 [[exemptions.web-time]]
 version = "1.1.0"
 criteria = "safe-to-deploy"