diff --git a/.changes/unreleased/internal-20261025-012014.yaml b/.changes/unreleased/internal-20261025-012014.yaml
new file mode 100644
index 0000000..cba446d
--- /dev/null
+++ b/.changes/unreleased/internal-20261025-012014.yaml
@@ -0,0 +1,5 @@
+kind: internal
+body: Lint code with Ameba in CI and the dev container
+time: 2026-10-25T01:20:14.000000+02:00
+custom:
+    Issue: ""
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 62c4bb1..f42e1c7 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -27,6 +27,15 @@ jobs:
       - uses: crystal-lang/install-crystal@v1
       - run: crystal tool format --check
 
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: crystal-ameba/github-action@v1
+        with:
+          # keep rules in sync with docker/dev.dockerfile
+          version: 1.7.0
+
   test:
     runs-on: ubuntu-latest
     steps:
diff --git a/AGENTS.md b/AGENTS.md
index 734d645..2a22afe 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -67,8 +67,14 @@ crystal spec --verbose                 # Verbose
 # Format (enforced by CI)
 crystal tool format src/ spec/         # Apply
 crystal tool format --check src/ spec/ # Check only
+
+# Lint (enforced by CI)
+ameba                                  # Check src/ and spec/
 ```
 
+Ameba is installed in the dev image (`docker/dev.dockerfile`). After a change
+to that file, run `docker compose build app`.
+
 ## Pull request guidelines
 
 **Branch naming:** Use dashes, not slashes (`feature-add-postgres-support`).
@@ -85,11 +91,11 @@ Kinds: `added`, `improved`, `changed`, `deprecated`, `removed`, `fixed`, `securi
 
 **Before submitting:**
 1. Tests pass
-2. Code formatted
+2. Code formatted and `ameba` passes
 3. Changelog entry added
 4. Rebased on main
 
-**CI checks:** Format, tests, changelog.
+**CI checks:** Format, lint, tests, changelog.
 
 ## Contribution policy
 
diff --git a/compose.yaml b/compose.yaml
index 3f5f793..d366f14 100644
--- a/compose.yaml
+++ b/compose.yaml
@@ -1,6 +1,10 @@
 services:
   app:
-    image: ghcr.io/luislavena/hydrofoil-crystal:${CRYSTAL_VERSION:-1.16}
+    build:
+      context: .
+      dockerfile: docker/dev.dockerfile
+      args:
+        CRYSTAL_VERSION: ${CRYSTAL_VERSION:-1.16}
     command: overmind start -f Procfile.dev
     working_dir: /workspace/${COMPOSE_PROJECT_NAME}
     environment:
diff --git a/docker/dev.dockerfile b/docker/dev.dockerfile
new file mode 100644
index 0000000..d5c0c76
--- /dev/null
+++ b/docker/dev.dockerfile
@@ -0,0 +1,37 @@
+# syntax=docker/dockerfile:1
+
+# ---
+# Development image: hydrofoil-crystal plus project-specific tools
+ARG CRYSTAL_VERSION=1.16
+FROM ghcr.io/luislavena/hydrofoil-crystal:${CRYSTAL_VERSION}
+
+# install development utilities
+RUN --mount=type=tmpfs,target=/tmp \
+    set -eux; \
+    cd /tmp; \
+    # Ameba
+    { \
+        export AMEBA_VERSION=1.7.0; \
+        case "$(arch)" in \
+        x86_64) \
+            export \
+                AMEBA_ARCH=x86_64 \
+                AMEBA_SHA256=7ed747711e76579902c5a4165a78a41b1e5acf0681ffcc538197bab435b4318f \
+            ; \
+            ;; \
+        aarch64) \
+            export \
+                AMEBA_ARCH=aarch64 \
+                AMEBA_SHA256=6467cdf69cae19ab3c52be93d2a1604e9b50e67fc20c7c1cb257117bd970837c \
+            ; \
+            ;; \
+        esac; \
+        curl --fail -Lo ameba.tar.gz https://github.com/crystal-ameba/ameba/releases/download/v${AMEBA_VERSION}/ameba-${AMEBA_VERSION}-linux-musl-${AMEBA_ARCH}.tar.gz; \
+        echo "${AMEBA_SHA256} *ameba.tar.gz" | sha256sum -c - >/dev/null 2>&1; \
+        tar -xf ameba.tar.gz; \
+        mv ameba /usr/local/bin/; \
+        rm -f ameba.tar.gz; \
+    }; \
+    # smoke tests
+    [ "$(command -v ameba)" = '/usr/local/bin/ameba' ]; \
+    ameba --version
diff --git a/src/drift/commands/new.cr b/src/drift/commands/new.cr
index b353f7d..14c5cba 100644
--- a/src/drift/commands/new.cr
+++ b/src/drift/commands/new.cr
@@ -18,10 +18,10 @@ module Drift
   module Commands
     class New < Command
       MIGRATION_TEMPLATE = <<-SQL
-      -- drift:up
+        -- drift:up
 
-      -- drift:down
-      SQL
+        -- drift:down
+        SQL
 
       def run(*args)
         migration_name = args.first?
diff --git a/src/drift/commands/status.cr b/src/drift/commands/status.cr
index 04798c1..6d8171d 100644
--- a/src/drift/commands/status.cr
+++ b/src/drift/commands/status.cr
@@ -49,7 +49,7 @@ module Drift
                   cell id.to_s
                 end
 
-                if migration = applied.find { |m| m.id == id }
+                if migration = applied.find { |entry| entry.id == id }
                   cell "Yes"
                   cell migration.batch.to_s, align: :right
                   cell migration.applied_at.to_s
diff --git a/src/drift/migration.cr b/src/drift/migration.cr
index 61e23be..a80ba44 100644
--- a/src/drift/migration.cr
+++ b/src/drift/migration.cr
@@ -23,15 +23,18 @@ module Drift
     # :nodoc:
     MAGIC_MARKER = "-- drift:"
 
+    # :nodoc:
+    DEPRECATED_MARKERS = {"migrate" => "up", "rollback" => "down"}
+
     getter id : Int64
     getter filename : String? = nil
 
     @statements : Hash(Type, Array(String))
 
     def initialize(@id : Int64, @filename : String? = nil)
-      @statements = Type.values.to_h { |type|
+      @statements = Type.values.to_h do |type|
         {type, Array(String).new}
-      }
+      end
     end
 
     def add(type : Type, statement : String)
@@ -48,39 +51,34 @@ module Drift
       @statements[type]
     end
 
+    # TODO: remove ameba:disable along with the deprecated markers support
+    # ameba:disable Metrics/CyclomaticComplexity
     def self.from_io(io, id : Int64, filename : String? = nil) : self
       migration = new(id, filename)
 
       buffer = IO::Memory.new
       type = nil
       multi_statement_mode = false
-      deprecated_warning_shown = false
+      deprecated_marker_found = false
 
       io.each_line do |line|
         stripped_line = line.strip
         # detect markers
         if stripped_line.starts_with?(MAGIC_MARKER)
-          case stripped_line[MAGIC_MARKER.size..-1]
+          raw_marker = stripped_line[MAGIC_MARKER.size..-1]
+          marker, deprecated = normalize_marker(raw_marker)
+          if deprecated && !deprecated_marker_found
+            STDERR.puts "DEPRECATED: 'drift:#{raw_marker}' marker in '#{filename || id}' is deprecated, use 'drift:#{marker}' instead"
+            deprecated_marker_found = true
+          end
+
+          case marker
           when "up"
             type = Type::Up
             next
           when "down"
             type = Type::Down
             next
-          when "migrate"
-            unless deprecated_warning_shown
-              STDERR.puts "DEPRECATED: 'drift:migrate' marker in '#{filename || id}' is deprecated, use 'drift:up' instead"
-              deprecated_warning_shown = true
-            end
-            type = Type::Up
-            next
-          when "rollback"
-            unless deprecated_warning_shown
-              STDERR.puts "DEPRECATED: 'drift:rollback' marker in '#{filename || id}' is deprecated, use 'drift:down' instead"
-              deprecated_warning_shown = true
-            end
-            type = Type::Down
-            next
           when "begin"
             multi_statement_mode = true
             next
@@ -113,6 +111,15 @@ module Drift
       migration
     end
 
+    # Returns the current name for a marker, and whether it was deprecated
+    private def self.normalize_marker(marker : String) : {String, Bool}
+      if replacement = DEPRECATED_MARKERS[marker]?
+        {replacement, true}
+      else
+        {marker, false}
+      end
+    end
+
     def self.load_file(filename : String) : self
       basename = File.basename(filename)