• SchemaSpec + TemplateSet + a pluggable PresetStore codec — a declarative, self-documenting template-file system (2026-06-27). A new shared layer for "named config/template files a user can model their own after," split into three composable, Qt-free, zero-dependency primitives so the shape and the storage of a template each have one SSoT. SchemaSpec (core_utils/schema_spec.py) is a base for schemas defined as a @dataclass: fields declared via spec_field(help=…, example=…, required=…, nested=…, choices=…, validate=…) carry their own documentation, and from that single definition the base derives — with no per-schema code — validate() (returns a ValidationResult that deliberately splits errors (unknown discriminator, wrong structure, missing required) from warnings (an unrecognised key; _-prefixed keys are reserved for annotations and never warned), so a file that merely carries an extra key keeps working; its raise_or_warn() is the one-call "enforce a validated file" helper every loader shares), skeleton() (a fully-populated example dict to copy, omitting unset optionals), generic from_dict/to_dict (recursing nested schemas), and describe()/to_markdown() (a field-by-field reference, nested schemas rendered as sub-tables — so the doc can never drift from the enforced shape). PresetStore gained an additive codec: Codec parameter (default JSON_CODEC, fully back-compatible — every existing caller and uitk's PresetManager are unaffected): a Codec(ext, load, dump) makes the store format-agnostic, so a caller can back *.yaml files by injecting a YAML codec without pythontk taking a YAML dependency (the caller supplies it). ext is now a property; discovery/path/load/save route through the codec. TemplateSet (core_utils/template_set.py) is the thin glue binding a PresetStore (two-tier built-in + user discovery, shadowing, last-used .active pointer) to a SchemaSpec (shape): names()/source()/user_dir/active, raw() (plain dict) vs load() (parse → validate → deserialise, raising on errors, logging warnings, strict= to raise on warnings too), skeleton(), save()/write_skeleton() (write arbitrary data or the generated skeleton to the user dir), and markdown(). Motivated by — and first consumed by — mayatk's Shot Manifest, whose CSV mapping (JSON) and behavior (YAML) template files were each globbed from inside the installed package with no user tier, no validation, and docstring-only schemas; both now share this one mechanism (see mayatk CHANGELOG 2026-06-27). Root exports: SchemaSpec, spec_field, ValidationResult, SchemaError, FieldDoc, Codec, JSON_CODEC, TemplateSet. Tests: test_schema_spec.py (19: validate errors/warnings/nested/choices/custom-validator, skeleton-is-self-valid, describe/markdown, round-trip), test_template_set.py (10: tiering, load-validates-and-raises, raw-skips-validation, skeleton/write_skeleton, user-shadows-builtin, custom-codec ext+IO), test_preset_store.py (+3 codec: default-is-JSON, custom-ext round-trip, cross-codec invisibility); 45 green pythontk-side, uitk PresetManager suite 74 green (consumer unaffected).