feat(extensions): scripts support, command filtering, and template discovery

[mbachorik]

Summary

Brings the extension system to parity with presets across three areas:

• Extension system: Add template type diversity (scripts support) #1847 — Scripts support: Extensions now accept provides.scripts alongside commands in the manifest. Includes name format validation (^[a-z0-9-]+$), path safety checks (no traversal), executable permissions on .sh files during install, and CLI display in extension list, extension add, and extension info.

• Extension system: Add extension filtering for ext-specific commands #1848 — Command filtering: Adds _filter_commands_for_installed_extensions() to CommandRegistrar — filters extension-specific commands (speckit.<ext-id>.<cmd>) against installed extension directories. Mirrors the preset filtering logic at presets.py:518-529. Available as a utility for cross-boundary filtering (e.g. when presets provide commands for extensions that may not be installed). Not applied during extension self-registration since all commands in an extension's own manifest are always valid.

• Extension system: Add template resolution system #1846 — Template resolution & discovery: Introduces ExtensionResolver — a dedicated class in extensions.py that owns extension template resolution, source attribution, and discovery. PresetResolver now delegates its tier-3 (extension) lookups to ExtensionResolver instead of walking extension directories directly. New specify preset list-templates --type <type> CLI command for template discovery across the full 4-tier stack.

Why ExtensionResolver instead of using PresetResolver?

The PresetResolver already had extension logic baked in (tier 3 of its resolution stack), but this meant extensions had to go through the preset system to discover their own templates — mixing concerns. ExtensionResolver gives extensions their own resolution/discovery API:

• resolve(name, type) — find a template from extensions
• resolve_with_source(name, type) — with source attribution
• list_templates(type) — discover all templates provided by extensions

PresetResolver remains the unified resolver across all 4 tiers (overrides → presets → extensions → core) but now delegates to ExtensionResolver for the extension tier rather than owning that logic directly. Each system owns its own domain.

Closes #1846, closes #1847, closes #1848

Test plan

• 843 tests pass (1 pre-existing failure in test_search_with_cached_data unrelated to this PR)
• Verify specify extension add with a scripts-only extension
• Verify specify preset list-templates outputs templates with correct source attribution
• Verify command filtering works when a preset provides commands for an uninstalled extension

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR extends Spec Kit’s extension and preset ecosystems to improve parity and discoverability: extensions can now declare scripts, commands can be filtered based on installed extensions, and presets gain a resolver-backed template discovery/listing command.

Changes:

• Add extension manifest + manager support for provides.scripts, including validation, install-time .sh executable bits, and CLI surface area (list/add/info).
• Introduce CommandRegistrar._filter_commands_for_installed_extensions() plus tests to filter speckit.<ext-id>.<cmd> commands when the target extension isn’t installed.
• Add PresetResolver.list_available() and a new specify preset list-templates --type <...> command, with template discovery tests.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/specify_cli/extensions.py	Adds scripts support to extension manifests/installs and introduces command filtering utility.
src/specify_cli/presets.py	Adds PresetResolver.list_available() for priority-stack template discovery with sources.
src/specify_cli/__init__.py	Adds preset list-templates CLI command and surfaces script counts in extension CLI output.
tests/test_extensions.py	Updates manifest validation tests and adds coverage for scripts support + command filtering utility.
tests/test_presets.py	Adds tests for PresetResolver.list_available() behavior (priority, sources, sorting).

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Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

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Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

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Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

src/specify_cli/extensions.py:160

• The commands/scripts validators assume each entry is a dict with string fields. If a manifest has provides.commands: ["foo"] or name/file values that aren’t strings, this will raise TypeError/KeyError (e.g., on cmd["name"] / regex) rather than a ValidationError. Validate isinstance(cmd, dict) and that name/file are strings before running regex/path checks.

        # Validate commands
        for cmd in commands:
            if "name" not in cmd or "file" not in cmd:
                raise ValidationError("Command missing 'name' or 'file'")

            # Validate command name format
            if not re.match(r'^speckit\.[a-z0-9-]+\.[a-z0-9-]+$', cmd["name"]):

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