diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index dbde1fd01d..172868aed6 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -1301,6 +1301,17 @@ Clue:
   tm_scope: source.clue
   ace_mode: text
   language_id: 163763508
+Cobrust:
+  type: programming
+  color: "#b45309"
+  extensions:
+  - ".cb"
+  tm_scope: source.cobrust
+  ace_mode: python
+  codemirror_mode: python
+  codemirror_mime_type: text/x-python
+  aliases:
+  - cobrust
 CoNLL-U:
   type: data
   extensions:
diff --git a/samples/Cobrust/fib.cb b/samples/Cobrust/fib.cb
new file mode 100644
index 0000000000..7875328e69
--- /dev/null
+++ b/samples/Cobrust/fib.cb
@@ -0,0 +1,14 @@
+# Fibonacci — M11.2 example (ADR-0034).
+#
+# Real recursive algorithm. Demonstrates user-defined fn calls via
+# `Constant::FnRef` Call lowering (forward-declaration two-pass per
+# ADR-0034 §"Decision" Option 3). fib(10) = 55.
+fn fib(n: i64) -> i64:
+    if n < 2:
+        return n
+    return fib(n - 1) + fib(n - 2)
+
+fn main() -> i64:
+    print("fib(10) =")
+    print(fib(10))
+    return 0
diff --git a/samples/Cobrust/fizzbuzz.cb b/samples/Cobrust/fizzbuzz.cb
new file mode 100644
index 0000000000..b2bfe1c2d2
--- /dev/null
+++ b/samples/Cobrust/fizzbuzz.cb
@@ -0,0 +1,24 @@
+# FizzBuzz — M11.1 example (ADR-0030).
+#
+# Real algorithm: while loop + if/elif/elif/else + modulo arithmetic.
+# Demonstrates:
+#   - while loop with mutation
+#   - if/elif/elif/else with if as the first statement in the loop body
+#   - modulo operator (%)
+#   - print (polymorphic: string and integer, ADR-0064)
+#
+# The M11 prelude fixes (ADR-0030) enable this after the while-loop-
+# with-leading-if codegen regression was resolved.
+fn main() -> i64:
+    let n: i64 = 1
+    while n <= 15:
+        if n % 15 == 0:
+            print("FizzBuzz")
+        elif n % 3 == 0:
+            print("Fizz")
+        elif n % 5 == 0:
+            print("Buzz")
+        else:
+            print(n)
+        n = n + 1
+    return 0
diff --git a/samples/Cobrust/hello.cb b/samples/Cobrust/hello.cb
new file mode 100644
index 0000000000..6dec94a81e
--- /dev/null
+++ b/samples/Cobrust/hello.cb
@@ -0,0 +1,3 @@
+fn main() -> i64:
+    print("hello, world")
+    return 0
diff --git a/samples/Cobrust/two_sum.cb b/samples/Cobrust/two_sum.cb
new file mode 100644
index 0000000000..986ea17214
--- /dev/null
+++ b/samples/Cobrust/two_sum.cb
@@ -0,0 +1,31 @@
+# LC-01 Two Sum (ADR-0044 W2 Phase 3).
+#
+# Input  (stdin):
+#   Line 1: N
+#   Lines 2..N+1: one integer each
+#   Line N+2: target
+#
+# Output: indices i j (i < j) with nums[i]+nums[j]==target, one per line.
+#
+# Algorithm: O(N²) brute-force scan.
+
+fn main() -> i64:
+    let n = parse_int(input(""))
+    let nums = list_new(n)
+    let i: i64 = 0
+    while i < n:
+        let v = parse_int(input(""))
+        list_set(nums, i, v)
+        i = i + 1
+    let target = parse_int(input(""))
+    let a: i64 = 0
+    while a < n:
+        let b: i64 = a + 1
+        while b < n:
+            if list_get(nums, a) + list_get(nums, b) == target:
+                print(a)
+                print(b)
+                return 0
+            b = b + 1
+        a = a + 1
+    return 0
diff --git a/samples/Cobrust/valid_anagram.cb b/samples/Cobrust/valid_anagram.cb
new file mode 100644
index 0000000000..d059900a73
--- /dev/null
+++ b/samples/Cobrust/valid_anagram.cb
@@ -0,0 +1,37 @@
+# LC-022 hashmap-valid-anagram (ADR-0047 LC-100 Tier A bucket B1).
+#
+# Input  (stdin): Line 1: string s; Line 2: string t
+# Output: "true" if s and t are anagrams, else "false"
+# Algorithm: 26-slot frequency count; increment for s, decrement for t
+
+fn main() -> i64:
+    let s = input("")
+    let t = input("")
+    let sn = str_len(&s)
+    let tn = str_len(&t)
+    if sn != tn:
+        print("false")
+        return 0
+    let freq = list_new(26)
+    let i: i64 = 0
+    while i < 26:
+        list_set(freq, i, 0)
+        i = i + 1
+    let j: i64 = 0
+    while j < sn:
+        let code = str_ord(str_at(&s, j)) - 97
+        list_set(freq, code, list_get(freq, code) + 1)
+        j = j + 1
+    let k: i64 = 0
+    while k < tn:
+        let code2 = str_ord(str_at(&t, k)) - 97
+        list_set(freq, code2, list_get(freq, code2) - 1)
+        k = k + 1
+    let m: i64 = 0
+    while m < 26:
+        if list_get(freq, m) != 0:
+            print("false")
+            return 0
+        m = m + 1
+    print("true")
+    return 0