Improve rules with filters, conditions, and scoped loading

[zikajk]

• Add YAML frontmatter support for filtering rules by agent, model, paths, and enforcement mode.

• Split rules into static prompt-injected rules and path-scoped rules that can be loaded on demand with fetch_rule.

• Add condition-variable rendering, /rules inspection, docs, and tests for the expanded rules behavior.

• I added a entry in changelog under unreleased section.

• This is not an AI slop.

[Copilot]

Pull request overview

This PR expands ECA’s rules system to support YAML-frontmatter filtering (agent/model/path/enforcement), splits rules into static vs path-scoped (on-demand) loading via a new fetch_rule tool, and adds Selmer condition-variable rendering plus /rules inspection with accompanying docs/tests.

Changes:

• Add YAML frontmatter parsing and rule filtering/partitioning into :static and :path-scoped, with path matching and enforcement metadata.
• Introduce fetch_rule tool and path-scoped rule enforcement gates for file tools (read/modify), plus prompt/catalog rendering updates.
• Add /rules command output, documentation updates, and comprehensive unit/integration tests.

Reviewed changes

Copilot reviewed 27 out of 27 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
test/eca/shared_test.clj	Adds coverage for new path normalization, Selmer rendering fallback behavior, and frontmatter parsing errors.
test/eca/features/tools_test.clj	Adds end-to-end tests for eca__fetch_rule and rule-enforced file tool flows.
test/eca/features/tools/filesystem_test.clj	Verifies enforcement gating behavior in filesystem tools depending on fetch_rule availability.
test/eca/features/rules_test.clj	Large expansion of rules tests for filtering, partitioning, matching, id lookup, and real-file loading.
test/eca/features/prompt_test.clj	Updates prompt-building tests for static/global/project rule grouping and path-scoped catalog rendering.
test/eca/features/commands_test.clj	Adds /rules command tests to validate output structure and filtering metadata display.
test/eca/features/chat_test.clj	Adds prompt cache reuse test to ensure cache keying includes both agent and model.
src/eca/shared.clj	Implements YAML frontmatter parsing, symlink-safe normalization, path-inside-root?, and safe-selmer-render.
src/eca/oauth.clj	Minor require/order changes to support Selmer usage consistently.
src/eca/features/tools/util.clj	Adds tool-available? helper and updates workspace path checks to use normalized path logic.
src/eca/features/tools/skill.clj	Adds :enabled-fn so skill tool is enabled only when skills exist.
src/eca/features/tools/path_rules.clj	New module to track per-chat validated path rules and compute missing enforced rules for read/modify.
src/eca/features/tools/filesystem.clj	Integrates path-scoped rule enforcement into read_file, write_file, and edit_file.
src/eca/features/tools/fetch_rule.clj	New fetch_rule tool: validates rule+path match, renders content with Selmer ctx, records validation.
src/eca/features/tools.clj	Wires fetch_rule into native tools and standardizes Selmer rendering via shared/safe-selmer-render.
src/eca/features/rules.clj	Reworks rule loading: parse frontmatter, filter by agent/model, partition static vs path-scoped, add path matching.
src/eca/features/prompt.clj	Updates prompt assembly to render static rules with grouping and include a path-scoped catalog when available.
src/eca/features/commands.clj	Adds /rules command implementation and formatting for static vs path-scoped rule visibility.
src/eca/features/chat.clj	Updates rule loading callsite and prompt-cache keying to include model (agent+model cache correctness).
src/eca/config.clj	Allows eca__fetch_rule in default approval policies for relevant agents/modes.
resources/prompts/tools/fetch_rule.md	Adds tool help text explaining id/path contract, glob semantics, and enforcement behavior.
mkdocs.yml	Adds “Templates” doc page to navigation.
integration-test/integration/chat/commands_test.clj	Ensures /rules appears in the available commands list.
docs/config/template.md	Documents Selmer condition variables for prompts/rules (including tool-enabled flags).
docs/config/rules.md	Major documentation update for rule sources, static vs path-scoped rules, frontmatter fields, and enforcement.
docs/config/agents.md	Links agent prompt customization to the new templates documentation.
CHANGELOG.md	Adds an unreleased entry describing the expanded rules functionality.

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