diff --git a/plugins/guides/api/routes.py b/plugins/guides/api/routes.py
index 293af01b..ac59426c 100644
--- a/plugins/guides/api/routes.py
+++ b/plugins/guides/api/routes.py
@@ -84,7 +84,7 @@ def _slugify(title, guideid=None):
     somebody pasted into a work order months ago.
     """
     base = re.sub(r'[^a-z0-9]+', '-', (title or '').lower()).strip('-') or 'guide'
-    base = base[:200]
+    base = base[:180]   # room for a '-2' style suffix inside the 191 cap
     candidate = base
     suffix = 2
     while True:
@@ -135,7 +135,7 @@ def list_guides():
             Guide.createdby == mine,
         ))
 
-    rows = query.order_by(Guide.updatedat.desc()).all()
+    rows = query.order_by(Guide.modifieddate.desc()).all()
 
     out = []
     for guide in rows:
diff --git a/plugins/guides/frontend/components/GuideBlocks.vue b/plugins/guides/frontend/components/GuideBlocks.vue
index 941a1457..3ddd31b9 100644
--- a/plugins/guides/frontend/components/GuideBlocks.vue
+++ b/plugins/guides/frontend/components/GuideBlocks.vue
@@ -230,11 +230,21 @@ async function copy (block) {
 .gb-table th { background: var(--surface-2, rgba(127,127,127,0.08)); }
 
 @media print {
-  /* Paper has no hover, no clipboard and no theme. */
+  /* Paper has no hover, no clipboard and no theme. The light-mode token
+     overrides live in GuideView.vue, which can reach :root; this block is only
+     about what belongs on paper. */
   .gb-copy { display: none; }
-  .gb-step, .gb-callout, .gb-code, .gb-figure { break-inside: avoid; }
-  .gb-check input { /* keep the box, printed empty, so it can be ticked by hand */ }
+  .gb-step, .gb-callout, .gb-code, .gb-figure, .gb-check { break-inside: avoid; }
+
+  /* Checkboxes print EMPTY on purpose, even where they are ticked on screen:
+     a printed guide is a worksheet somebody carries to the bay and ticks by
+     hand, and one person's progress is not part of the procedure. */
   .gb-done { opacity: 1; text-decoration: none; }
+  .gb-check input { appearance: none; -webkit-appearance: none;
+                    width: 0.85rem; height: 0.85rem; border: 1px solid #000;
+                    border-radius: 2px; background: #fff; }
+
   .gb-code pre { white-space: pre-wrap; }
+  .gb-stepnum { color: #000; }
 }
 </style>
diff --git a/plugins/guides/frontend/views/GuideView.vue b/plugins/guides/frontend/views/GuideView.vue
index fb2e61c0..e0ff3686 100644
--- a/plugins/guides/frontend/views/GuideView.vue
+++ b/plugins/guides/frontend/views/GuideView.vue
@@ -218,3 +218,54 @@ watch(() => route.params.slug, load)
   .gv-foot { border-top: 1px solid #999; }
 }
 </style>
+
+<style>
+/*
+ * PRINT IS ALWAYS LIGHT, whatever the screen theme is.
+ *
+ * Printing a dark-mode page lays down a full page of toner for the background
+ * and then knocks the text out of it in white. On a shopfloor printer that is
+ * a cartridge for a handful of guides, and the result is harder to read than
+ * the plain version.
+ *
+ * So the theme tokens are redefined for print only. Every guide element already
+ * renders through these variables rather than literal colours, which is what
+ * makes this a dozen lines instead of a rewrite - and the same discipline that
+ * made dark mode work at all.
+ *
+ * Deliberately NOT scoped: a scoped block cannot reach :root, and these have to
+ * override tokens set on the document element.
+ */
+@media print {
+  :root,
+  :root[data-theme="dark"],
+  :root[data-theme="light"] {
+    --text: #000;
+    --text-light: #333;
+    --border: #999;
+    --surface: #fff;
+    --surface-2: #fff;
+    --primary: #000;
+    --info: #666;
+    --warning: #666;
+    --success: #666;
+  }
+
+  html, body, .app-layout, .main-content {
+    background: #fff !important;
+    color: #000 !important;
+  }
+
+  /* Backgrounds are dropped rather than printed grey: a callout is identified
+     by its rule and its heading, which cost nothing to print. */
+  .gb-callout, .gb-code, .gb-codehead, .gb-table th {
+    background: #fff !important;
+  }
+  .gb-callout { border-left: 3px solid #000 !important; }
+  .gb-code, .gb-table th, .gb-table td { border-color: #999 !important; }
+
+  /* Links: the text is what matters on paper, and a blue underline on a mono
+     printer is just grey. */
+  a { color: #000 !important; text-decoration: underline; }
+}
+</style>
diff --git a/plugins/guides/migrations/versions/0001_guides_baseline.py b/plugins/guides/migrations/versions/0001_guides_baseline.py
index 2ebd51f1..8964c3a7 100644
--- a/plugins/guides/migrations/versions/0001_guides_baseline.py
+++ b/plugins/guides/migrations/versions/0001_guides_baseline.py
@@ -30,7 +30,9 @@ def upgrade():
             'guides',
             sa.Column('guideid', sa.Integer(), nullable=False),
             sa.Column('title', sa.String(length=300), nullable=False),
-            sa.Column('slug', sa.String(length=300), nullable=False),
+            # 191 because this is UNIQUE-indexed and MySQL caps an index key at
+            # 767 bytes; utf8mb4 is 4 bytes per character.
+            sa.Column('slug', sa.String(length=191), nullable=False),
             sa.Column('summary', sa.String(length=1000)),
             sa.Column('tags', sa.String(length=500)),
             sa.Column('status', sa.String(length=20), nullable=False,
@@ -41,9 +43,13 @@ def upgrade():
             sa.Column('publishedrevisionid', sa.Integer()),
             sa.Column('createdby', sa.Integer()),
             sa.Column('updatedby', sa.Integer()),
-            sa.Column('createdat', sa.DateTime(), nullable=False),
-            sa.Column('updatedat', sa.DateTime(), nullable=False),
             sa.Column('publishedat', sa.DateTime()),
+            # BaseModel contributes these to every model in the app; a plugin
+            # migration has to spell them out or the table is missing columns
+            # the ORM selects on every query.
+            sa.Column('createddate', sa.DateTime(), nullable=False),
+            sa.Column('modifieddate', sa.DateTime(), nullable=False),
+            sa.Column('isactive', sa.Boolean(), nullable=False),
             sa.Column('revision', sa.Integer(), nullable=False, server_default='1'),
             sa.PrimaryKeyConstraint('guideid'),
             sa.UniqueConstraint('slug', name='uq_guides_slug'),
@@ -65,7 +71,12 @@ def upgrade():
             sa.Column('contenthash', sa.String(length=64), nullable=False),
             sa.Column('note', sa.String(length=500)),
             sa.Column('createdby', sa.Integer()),
-            sa.Column('createdat', sa.DateTime(), nullable=False),
+            # BaseModel contributes these to every model in the app; a plugin
+            # migration has to spell them out or the table is missing columns
+            # the ORM selects on every query.
+            sa.Column('createddate', sa.DateTime(), nullable=False),
+            sa.Column('modifieddate', sa.DateTime(), nullable=False),
+            sa.Column('isactive', sa.Boolean(), nullable=False),
             sa.PrimaryKeyConstraint('guiderevisionid'),
             sa.ForeignKeyConstraint(['guideid'], ['guides.guideid'],
                                     ondelete='CASCADE'),
@@ -85,7 +96,12 @@ def upgrade():
                       if op.get_bind().dialect.name == 'mysql' else sa.LargeBinary(),
                       nullable=False),
             sa.Column('uploadedby', sa.Integer()),
-            sa.Column('createdat', sa.DateTime(), nullable=False),
+            # BaseModel contributes these to every model in the app; a plugin
+            # migration has to spell them out or the table is missing columns
+            # the ORM selects on every query.
+            sa.Column('createddate', sa.DateTime(), nullable=False),
+            sa.Column('modifieddate', sa.DateTime(), nullable=False),
+            sa.Column('isactive', sa.Boolean(), nullable=False),
             sa.PrimaryKeyConstraint('guideimageid'),
             sa.ForeignKeyConstraint(['guideid'], ['guides.guideid'],
                                     ondelete='CASCADE'),
diff --git a/plugins/guides/models/guide.py b/plugins/guides/models/guide.py
index 6cbda923..a3587798 100644
--- a/plugins/guides/models/guide.py
+++ b/plugins/guides/models/guide.py
@@ -74,7 +74,12 @@ class Guide(BaseModel):
     # derived on read so an edited title cannot silently break a link somebody
     # pasted into a work order.
     title = db.Column(db.String(300), nullable=False)
-    slug = db.Column(db.String(300), nullable=False, unique=True, index=True)
+    # 191, not 300: this column is UNIQUE-indexed, and MySQL caps an index key
+    # at 767 bytes. utf8mb4 stores up to 4 bytes per character, so 191 * 4 =
+    # 764 is the longest indexable string - 300 produces
+    # "Specified key was too long" the moment the migration runs on a real
+    # database, having passed every SQLite test.
+    slug = db.Column(db.String(191), nullable=False, unique=True, index=True)
 
     # One line, shown in the list and in search results.
     summary = db.Column(db.String(1000))
@@ -114,11 +119,12 @@ class Guide(BaseModel):
                                   use_alter=True,
                                   name='fk_guides_publishedrevision'))
 
+    # createddate / modifieddate / isactive come from BaseModel - no second set
+    # of timestamps on top of them, or the next person has to work out which
+    # pair is authoritative. publishedat is ours because "when did readers start
+    # seeing this" is a different fact from "when was the row last touched".
     createdby = db.Column(db.Integer, db.ForeignKey('users.userid'))
     updatedby = db.Column(db.Integer, db.ForeignKey('users.userid'))
-    createdat = db.Column(db.DateTime, nullable=False, default=_utcnow)
-    updatedat = db.Column(db.DateTime, nullable=False, default=_utcnow,
-                          onupdate=_utcnow)
     publishedat = db.Column(db.DateTime)
 
     # The working copy's version number. Bumped only when a save actually
@@ -161,8 +167,10 @@ class Guide(BaseModel):
             'tags': self.taglist(),
             'status': self.status,
             'revision': self.revision,
-            'createdat': self.createdat.isoformat() + 'Z' if self.createdat else None,
-            'updatedat': self.updatedat.isoformat() + 'Z' if self.updatedat else None,
+            # API names stay createdat/updatedat: the column names are a
+            # storage detail, and renaming a payload field breaks callers.
+            'createdat': self.createddate.isoformat() + 'Z' if self.createddate else None,
+            'updatedat': self.modifieddate.isoformat() + 'Z' if self.modifieddate else None,
             'publishedat': (self.publishedat.isoformat() + 'Z'
                             if self.publishedat else None),
         }
@@ -212,7 +220,6 @@ class GuideRevision(BaseModel):
     note = db.Column(db.String(500))
 
     createdby = db.Column(db.Integer, db.ForeignKey('users.userid'))
-    createdat = db.Column(db.DateTime, nullable=False, default=_utcnow)
 
     @property
     def blocks(self):
@@ -234,7 +241,7 @@ class GuideRevision(BaseModel):
             'tags': [t.strip() for t in (self.tags or '').split(',') if t.strip()],
             'note': self.note,
             'createdby': self.createdby,
-            'createdat': self.createdat.isoformat() + 'Z' if self.createdat else None,
+            'createdat': self.createddate.isoformat() + 'Z' if self.createddate else None,
             'shorthash': (self.contenthash or '')[:12],
         }
         if includeblocks:
@@ -268,7 +275,6 @@ class GuideImage(BaseModel):
     data = db.Column(db.LargeBinary(length=(2 ** 24) - 1), nullable=False)
 
     uploadedby = db.Column(db.Integer, db.ForeignKey('users.userid'))
-    createdat = db.Column(db.DateTime, nullable=False, default=_utcnow)
 
     def to_dict(self):
         return {
@@ -278,5 +284,5 @@ class GuideImage(BaseModel):
             'mimetype': self.mimetype,
             'bytesize': self.bytesize,
             'url': '/api/guides/images/{}'.format(self.guideimageid),
-            'createdat': self.createdat.isoformat() + 'Z' if self.createdat else None,
+            'createdat': self.createddate.isoformat() + 'Z' if self.createddate else None,
         }
diff --git a/plugins/guides/services/authoring.py b/plugins/guides/services/authoring.py
index d645d2f0..1afd4389 100644
--- a/plugins/guides/services/authoring.py
+++ b/plugins/guides/services/authoring.py
@@ -52,7 +52,6 @@ def save(guide, title=None, summary=None, tags=None, blocks=None, note=None,
 
     guide.revision = (latest.revision + 1) if latest else 1
     guide.updatedby = userid
-    guide.updatedat = _utcnow()
 
     revision = GuideRevision(
         guideid=guide.guideid,