modifiers

name	modifiers
description	Object modifiers and constraints. Use to inspect, add, edit, or delete modifiers/constraints; query type-specific fields via params_json.
allowed-tools	["Bash","Read","Glob","Grep"]

The modifier stack and the constraint stack on objects (and bones). Both carry their type-specific fields as a JSON blob in params_json — query into it with json_extract, write to it by passing a JSON object.

---

Tables

Table	RW	Key columns
modifiers	RW (UPDATE/DELETE)	object, name, type (SUBSURF/ARRAY/MIRROR/SOLIDIFY/NODES/…), show_viewport, show_render, params_json
constraints	RW (UPDATE/DELETE)	owner_type (OBJECT/BONE), owner_name, name, type (COPY_LOCATION/TRACK_TO/CHILD_OF/LIMIT_ROTATION/…), target, subtarget, influence, mute, params_json

params_json holds the fields that vary by modifier/constraint type — {"levels": 2, "render_levels": 3} for SUBSURF, {"count": 5, "use_relative_offset": true} for ARRAY, etc. Discovery: PRAGMA table_info(modifiers); · SELECT object, name, type, params_json FROM modifiers WHERE object='Cube'; to see what keys a given one has.

Canonical writability + one-line descriptions kept in sync by scripts/regen_skills.py:

name	writable	description
constraints	yes	Object and pose-bone constraints: target binding, influence, packed params.
modifiers	yes	Per-object modifier stack with type and packed parameters.

---

Common Queries

-- Modifier stack on an object (order = stack order)
SELECT name, type, show_viewport, show_render FROM modifiers WHERE object='Cube';

-- Every object that has a Subsurf, with its level
SELECT object, name, json_extract(params_json,'$.levels') AS levels,
       json_extract(params_json,'$.render_levels') AS render_levels
FROM modifiers WHERE type='SUBSURF' ORDER BY object;

-- Geometry-nodes modifiers and the node group they run
SELECT object, name, json_extract(params_json,'$.node_group') AS node_group FROM modifiers WHERE type='NODES';

-- Modifier histogram across the file
SELECT type, COUNT(*) FROM modifiers GROUP BY type ORDER BY 2 DESC;

-- Constraints on an object
SELECT name, type, target, subtarget, influence, mute FROM constraints WHERE owner_name='Cube';

-- Bone constraints (owner_type='BONE'; owner_name is the pose-bone name)
SELECT owner_name, name, type, target, subtarget, influence FROM constraints WHERE owner_type='BONE' ORDER BY owner_name;

-- Constraints pointing at a given target object
SELECT owner_type, owner_name, type, influence FROM constraints WHERE target='Empty';

-- Type-specific constraint field (e.g. TRACK_TO axis)
SELECT owner_name, json_extract(params_json,'$.track_axis') AS track_axis FROM constraints WHERE type='TRACK_TO';

---

Writing

modifiers — UPDATE / DELETE

params_json is the whole knob set; assigning it applies each field in the object.

-- Bump Subsurf levels
UPDATE modifiers SET params_json='{"levels":3,"render_levels":4}' WHERE object='Cube' AND name='Subsurf';

-- Turn a modifier off in the viewport but keep it for render
UPDATE modifiers SET show_viewport=0, show_render=1 WHERE object='Cube' AND type='SUBSURF';

-- Reconfigure an Array modifier
UPDATE modifiers SET params_json='{"count":6,"use_relative_offset":true,"relative_offset_displace":[1.2,0,0]}'
WHERE object='Fence' AND type='ARRAY';

-- Rename / delete a modifier
UPDATE modifiers SET name='SubD' WHERE object='Cube' AND name='Subsurf';
DELETE FROM modifiers WHERE object='Cube' AND name='SubD';

You can't change a modifier's type by UPDATE — delete it and add a fresh one. You can't INSERT a modifier directly either — use the verb.

constraints — UPDATE / DELETE

-- Dial influence, mute, retarget
UPDATE constraints SET influence=0.5 WHERE owner_name='Cube' AND name='Copy Location';
UPDATE constraints SET mute=1 WHERE owner_name='Cube' AND type='LIMIT_ROTATION';
UPDATE constraints SET target='NewTarget', subtarget='Head' WHERE owner_name='Cube' AND name='Track To';

-- Type-specific tweak
UPDATE constraints SET params_json='{"track_axis":"TRACK_NEGATIVE_Z","up_axis":"UP_Y"}'
WHERE owner_name='Cube' AND type='TRACK_TO';

-- Delete
DELETE FROM constraints WHERE owner_name='Cube' AND name='Track To';

Verbs — add modifiers and constraints

-- add_modifier(object, type, params_json?)
SELECT add_modifier('Cube', 'SUBSURF', '{"levels":2,"render_levels":3}');
SELECT add_modifier('Fence', 'ARRAY', '{"count":5}');
SELECT add_modifier('Cube', 'NODES', '{"node_group":"MyGeoNodes"}');

-- add_constraint(object, type, target?, params_json?)
SELECT add_constraint('Cube', 'COPY_LOCATION', 'Empty');
SELECT add_constraint('Cube', 'TRACK_TO', 'Camera', '{"track_axis":"TRACK_NEGATIVE_Z","up_axis":"UP_Y"}');
SELECT add_constraint('Cube', 'LIMIT_ROTATION', NULL, '{"use_limit_x":true,"max_x":1.0}');

Verb failures (bad type, missing object/target, rejected param) come back inside the JSON envelope, not as a SQL error. Bone constraints aren't covered by add_constraint yet — use bpy_exec (pose_bone.constraints.new('COPY_ROTATION')).

---

Gotchas

• params_json is type-specific. To know which keys a modifier/constraint accepts, read its current params_json, or check bpy_eval('[p.identifier for p in bpy.data.objects["Cube"].modifiers["Subsurf"].bl_rna.properties]').
• Assigning params_json sets the listed fields and only those; unlisted fields keep their current value (it's not a full replace of the modifier).
• Stack order = row order in modifiers for an object; there's no reorder via SQL — use bpy_op('object.modifier_move_to_index', ...).
• bpy_op('object.modifier_apply', '{"modifier":"Subsurf"}', '{"active_object":"Cube"}') to apply (bake) a modifier — that's an operator, not a row write.
• Constraint subtarget only matters when target is an armature (it's the bone name); for object targets leave it empty.