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fallow_api/
explain.rs

1//! Metric and rule definitions for explainable CLI output.
2//!
3//! Provides structured metadata that describes what each metric, threshold,
4//! and rule means, consumed by the `_meta` object in JSON output and by
5//! SARIF `fullDescription` / `helpUri` fields.
6
7use serde_json::Value;
8
9const DOCS_BASE: &str = "https://docs.fallow.tools";
10
11/// Rule definition for SARIF `fullDescription` and JSON `_meta`.
12pub struct RuleDef {
13    pub id: &'static str,
14    /// Coarse category label used by the sticky PR/MR comment renderer to
15    /// group findings into collapsible sections (Dead code, Dependencies,
16    /// Duplication, Health, Architecture, Suppressions). One source of
17    /// truth so the CodeClimate / SARIF / review-envelope path and the
18    /// renderer never drift; a unit test below asserts every RuleDef has
19    /// a non-empty category.
20    pub category: &'static str,
21    pub name: &'static str,
22    pub short: &'static str,
23    pub full: &'static str,
24    pub docs_path: &'static str,
25}
26
27pub const CHECK_RULES: &[RuleDef] = &[
28    RuleDef {
29        id: "fallow/unused-file",
30        category: "Dead code",
31        name: "Unused Files",
32        short: "File is not reachable from any entry point",
33        full: "Source files that are not imported by any other module and are not entry points (scripts, tests, configs). These files can safely be deleted. Detection uses graph reachability from configured entry points.",
34        docs_path: "explanations/dead-code#unused-files",
35    },
36    RuleDef {
37        id: "fallow/unused-export",
38        category: "Dead code",
39        name: "Unused Exports",
40        short: "Export is never imported",
41        full: "Named exports that are never imported by any other module in the project. Includes both direct exports and re-exports through barrel files. The export may still be used locally within the same file.",
42        docs_path: "explanations/dead-code#unused-exports",
43    },
44    RuleDef {
45        id: "fallow/unused-type",
46        category: "Dead code",
47        name: "Unused Type Exports",
48        short: "Type export is never imported",
49        full: "Type-only exports (interfaces, type aliases, enums used only as types) that are never imported. These do not generate runtime code but add maintenance burden.",
50        docs_path: "explanations/dead-code#unused-types",
51    },
52    RuleDef {
53        id: "fallow/private-type-leak",
54        category: "Dead code",
55        name: "Private Type Leaks",
56        short: "Exported signature references a private type",
57        full: "Exported values or types whose public TypeScript signature references a same-file type declaration that is not exported. Consumers cannot name that private type directly, so the backing type should be exported or removed from the public signature.",
58        docs_path: "explanations/dead-code#private-type-leaks",
59    },
60    RuleDef {
61        id: "fallow/unused-dependency",
62        category: "Dependencies",
63        name: "Unused Dependencies",
64        short: "Dependency listed but never imported",
65        full: "Packages listed in dependencies that are never imported or required by any source file. Framework plugins and CLI tools may be false positives; use the ignore_dependencies config to suppress.",
66        docs_path: "explanations/dead-code#unused-dependencies",
67    },
68    RuleDef {
69        id: "fallow/unused-dev-dependency",
70        category: "Dependencies",
71        name: "Unused Dev Dependencies",
72        short: "Dev dependency listed but never imported",
73        full: "Packages listed in devDependencies that are never imported by test files, config files, or scripts. Build tools and jest presets that are referenced only in config may appear as false positives.",
74        docs_path: "explanations/dead-code#unused-devdependencies",
75    },
76    RuleDef {
77        id: "fallow/unused-optional-dependency",
78        category: "Dependencies",
79        name: "Unused Optional Dependencies",
80        short: "Optional dependency listed but never imported",
81        full: "Packages listed in optionalDependencies that are never imported. Optional dependencies are typically platform-specific; verify they are not needed on any supported platform before removing.",
82        docs_path: "explanations/dead-code#unused-optionaldependencies",
83    },
84    RuleDef {
85        id: "fallow/type-only-dependency",
86        category: "Dependencies",
87        name: "Type-only Dependencies",
88        short: "Production dependency only used via type-only imports",
89        full: "Production dependencies that are only imported via `import type` statements. These can be moved to devDependencies since they generate no runtime code and are stripped during compilation.",
90        docs_path: "explanations/dead-code#type-only-dependencies",
91    },
92    RuleDef {
93        id: "fallow/test-only-dependency",
94        category: "Dependencies",
95        name: "Test-only Dependencies",
96        short: "Production dependency only imported by test files",
97        full: "Production dependencies that are only imported from test files. These can usually move to devDependencies because production entry points do not require them at runtime.",
98        docs_path: "explanations/dead-code#test-only-dependencies",
99    },
100    RuleDef {
101        id: "fallow/unused-enum-member",
102        category: "Dead code",
103        name: "Unused Enum Members",
104        short: "Enum member is never referenced",
105        full: "Enum members that are never referenced in the codebase. Uses scope-aware binding analysis to track all references including computed access patterns.",
106        docs_path: "explanations/dead-code#unused-enum-members",
107    },
108    RuleDef {
109        id: "fallow/unused-class-member",
110        category: "Dead code",
111        name: "Unused Class Members",
112        short: "Class member is never referenced",
113        full: "Class methods and properties that are never referenced outside the class. Private members are checked within the class scope; public members are checked project-wide.",
114        docs_path: "explanations/dead-code#unused-class-members",
115    },
116    RuleDef {
117        id: "fallow/unused-store-member",
118        category: "Dead code",
119        name: "Unused Store Members",
120        short: "Store member is never accessed by any consumer",
121        full: "Pinia store members (a `state` / `getters` / `actions` key, or a setup-store returned key) declared but never accessed by any consumer project-wide. The store binding is imported (so the module is reachable) yet a specific member is dead. Defaults to warn, not error: a store has an open declaration surface (plugins, dynamic dispatch) so confidence is lower. Activates only when pinia or @pinia/nuxt is a declared dependency.",
122        docs_path: "explanations/dead-code#unused-store-members",
123    },
124    RuleDef {
125        id: "fallow/unresolved-import",
126        category: "Dead code",
127        name: "Unresolved Imports",
128        short: "Import could not be resolved",
129        full: "Import specifiers that could not be resolved to a file on disk. Common causes: deleted files, typos in paths, missing path aliases in tsconfig, or uninstalled packages.",
130        docs_path: "explanations/dead-code#unresolved-imports",
131    },
132    RuleDef {
133        id: "fallow/unlisted-dependency",
134        category: "Dependencies",
135        name: "Unlisted Dependencies",
136        short: "Dependency used but not in package.json",
137        full: "Packages that are imported in source code but not listed in package.json. These work by accident (hoisted from another workspace package or transitive dep) and will break in strict package managers.",
138        docs_path: "explanations/dead-code#unlisted-dependencies",
139    },
140    RuleDef {
141        id: "fallow/duplicate-export",
142        category: "Dead code",
143        name: "Duplicate Exports",
144        short: "Export name appears in multiple modules",
145        full: "The same export name is defined in multiple modules. Consumers may import from the wrong module, leading to subtle bugs. Consider renaming or consolidating.",
146        docs_path: "explanations/dead-code#duplicate-exports",
147    },
148    RuleDef {
149        id: "fallow/circular-dependency",
150        category: "Architecture",
151        name: "Circular Dependencies",
152        short: "Circular dependency chain detected",
153        full: "A cycle in the module import graph. Circular dependencies cause undefined behavior with CommonJS (partial modules) and initialization ordering issues with ESM. Break cycles by extracting shared code.",
154        docs_path: "explanations/dead-code#circular-dependencies",
155    },
156    RuleDef {
157        id: "fallow/re-export-cycle",
158        category: "Architecture",
159        name: "Re-Export Cycles",
160        short: "Two or more barrel files re-export from each other in a loop",
161        full: "A barrel file re-exports from another barrel that ultimately re-exports back. When this happens, imports from any file in the loop may silently come up empty, because the re-export chain has no terminating module to resolve names against. To fix this: open any one file in the loop and remove the `export * from` (or `export { ... } from`) statement that points back into the cycle. Any single removal will break the cycle and restore working re-exports. A self-loop (a single barrel re-exporting from itself, often a rename leftover) is reported under the same rule with kind `self-loop`.",
162        docs_path: "explanations/dead-code#re-export-cycles",
163    },
164    RuleDef {
165        id: "fallow/boundary-violation",
166        category: "Architecture",
167        name: "Boundary Violations",
168        short: "Import crosses a configured architecture boundary",
169        full: "A module imports from a zone that its configured boundary rules do not allow. Boundary checks help keep layered architecture, feature slices, and package ownership rules enforceable.",
170        docs_path: "explanations/dead-code#boundary-violations",
171    },
172    RuleDef {
173        id: "fallow/boundary-coverage",
174        category: "Architecture",
175        name: "Boundary Coverage",
176        short: "Source file matches no configured architecture boundary zone",
177        full: "A reachable source file is not assigned to any configured boundary zone while boundaries.coverage.requireAllFiles is enabled. Add the file to a zone pattern, move it under an existing zone, or allow-list generated and intentionally unzoned paths with boundaries.coverage.allowUnmatched.",
178        docs_path: "explanations/dead-code#boundary-violations",
179    },
180    RuleDef {
181        id: "fallow/boundary-call-violation",
182        category: "Architecture",
183        name: "Boundary Call Violation",
184        short: "Zoned file calls a callee its zone forbids",
185        full: "A file classified into a boundary zone calls a callee matching one of the zone's boundaries.calls.forbidden patterns. The check is syntactic: it matches the written callee path and the import-resolved canonical path, and it only applies to files classified into a zone. Move the call behind an allowed abstraction, or adjust the zone's forbidden patterns if the rule was wrong.",
186        docs_path: "explanations/dead-code#boundary-violations",
187    },
188    RuleDef {
189        id: "fallow/policy-violation",
190        category: "Policy",
191        name: "Policy Violation",
192        short: "Banned usage matched a rule-pack rule",
193        full: "A call site, import, or catalogue-derived effect matched a rule from a configured rule pack (the rulePacks config key). Packs are pure declarative data; the check is syntactic, call and effect matching use written plus import-resolved canonical callees, and import matching uses the raw specifier. Replace the banned usage per the rule's message, scope the rule with files/exclude globs, or adjust its severity.",
194        docs_path: "explanations/dead-code#policy-violations",
195    },
196    RuleDef {
197        id: "fallow/stale-suppression",
198        category: "Suppressions",
199        name: "Stale Suppressions",
200        short: "Suppression comment or tag no longer matches any issue",
201        full: "A fallow-ignore-next-line, fallow-ignore-file, or @expected-unused suppression that no longer matches any active issue. The underlying problem was fixed but the suppression was left behind. Remove it to keep the codebase clean.",
202        docs_path: "explanations/dead-code#stale-suppressions",
203    },
204    RuleDef {
205        id: "fallow/missing-suppression-reason",
206        category: "Suppressions",
207        name: "Missing Suppression Reason",
208        short: "Suppression comment omits a required reason",
209        full: "A fallow-ignore-next-line or fallow-ignore-file suppression omits the explanatory reason required by the requireSuppressionReason rule. Add a short reason after the suppression token, or remove the suppression if the issue is no longer intentional.",
210        docs_path: "explanations/dead-code#stale-suppressions",
211    },
212    RuleDef {
213        id: "fallow/unused-catalog-entry",
214        category: "Dependencies",
215        name: "Unused catalog entry",
216        short: "Catalog entry not referenced by any workspace package",
217        full: "An entry in a package manager catalog (`pnpm-workspace.yaml` `catalog:` / `catalogs:` or Bun root `package.json` `workspaces.catalog` / `workspaces.catalogs`) that no workspace package.json references via the `catalog:` protocol. Catalog entries are leftover dependency metadata once a package is removed from every consumer; delete the entry to keep the catalog truthful. See also: fallow/unresolved-catalog-reference (the inverse: consumer references a catalog that does not declare the package).",
218        docs_path: "explanations/dead-code#unused-catalog-entries",
219    },
220    RuleDef {
221        id: "fallow/empty-catalog-group",
222        category: "Dependencies",
223        name: "Empty catalog group",
224        short: "Named catalog group has no entries",
225        full: "A named group under `catalogs:` in `pnpm-workspace.yaml` or Bun root `package.json` has no package entries. Empty named groups are leftover catalog structure after the last entry is removed. The default `catalog` map is intentionally ignored because some projects keep it as a stable hook.",
226        docs_path: "explanations/dead-code#empty-catalog-groups",
227    },
228    RuleDef {
229        id: "fallow/unresolved-catalog-reference",
230        category: "Dependencies",
231        name: "Unresolved catalog reference",
232        short: "package.json references a catalog that does not declare the package",
233        full: "A workspace package.json declares a dependency with the `catalog:` or `catalog:<name>` protocol, but the catalog has no entry for that package. The package manager install will fail until the catalog is fixed. To fix: add the package to the named catalog, switch the reference to a different catalog that does declare it, or remove the reference and pin a hardcoded version. Scope: the detector scans `dependencies`, `devDependencies`, `peerDependencies`, and `optionalDependencies` in every workspace `package.json`, using `pnpm-workspace.yaml` catalogs when present and Bun root `package.json` catalogs otherwise. See also: fallow/unused-catalog-entry (the inverse: catalog entries no consumer references).",
234        docs_path: "explanations/dead-code#unresolved-catalog-references",
235    },
236    RuleDef {
237        id: "fallow/unused-dependency-override",
238        category: "Dependencies",
239        name: "Unused pnpm dependency override",
240        short: "pnpm.overrides entry targets a package not declared or resolved",
241        full: "An entry in `pnpm-workspace.yaml`'s `overrides:` section, or the root `package.json`'s `pnpm.overrides` block, whose target package is not declared by any workspace package and is not present in `pnpm-lock.yaml`. Override entries linger after their target package leaves the resolved dependency tree. For projects without a readable lockfile, fallow falls back to workspace package.json manifests and keeps a `hint` so transitive CVE pins can be reviewed before removal. To fix: delete the entry, refresh `pnpm-lock.yaml` if it is stale, or add the entry to `ignoreDependencyOverrides` when the override is intentionally retained. See also: fallow/misconfigured-dependency-override.",
242        docs_path: "explanations/dead-code#unused-dependency-overrides",
243    },
244    RuleDef {
245        id: "fallow/misconfigured-dependency-override",
246        category: "Dependencies",
247        name: "Misconfigured pnpm dependency override",
248        short: "pnpm.overrides entry has an unparsable key or value",
249        full: "An entry in `pnpm-workspace.yaml`'s `overrides:` or `package.json`'s `pnpm.overrides` whose key or value does not parse as a valid pnpm override spec. Common shapes: empty key, empty value, malformed version selector on the target (`@types/react@<<18`), unbalanced parent matcher (`react>`), or unsupported `npm:alias@` syntax in the version (only the `-`, `$ref`, and `npm:alias` pnpm idioms are allowed). pnpm rejects the workspace at install time with a parser error. To fix: correct the key/value shape, or remove the entry. See also: fallow/unused-dependency-override.",
250        docs_path: "explanations/dead-code#misconfigured-dependency-overrides",
251    },
252    RuleDef {
253        id: "fallow/invalid-client-export",
254        category: "Policy",
255        name: "Invalid client export",
256        short: "\"use client\" file exports a server-only / route-config name",
257        full: "A file carrying the `\"use client\"` directive also exports a Next.js server-only or route-segment config name (such as `metadata`, `generateMetadata`, `revalidate`, `generateStaticParams`, or a route HTTP method like `GET`/`POST`). Next.js rejects this combination at build time. Move the server-only export to a non-client module (a server component, a `route.ts`, or a separate config file), or remove the `\"use client\"` directive if the module does not need to be a client boundary. The check runs only when the project declares `next`.",
258        docs_path: "explanations/dead-code#invalid-client-exports",
259    },
260    RuleDef {
261        id: "fallow/mixed-client-server-barrel",
262        category: "Policy",
263        name: "Mixed client/server barrel",
264        short: "Barrel re-exports both a \"use client\" module and a server-only module",
265        full: "A barrel file (a module whose exports are `export ... from` re-exports) forwards a name from a `\"use client\"` module alongside a name from a server-only module (one carrying `\"use server\"`, importing the `server-only` package, or importing a server-only Next.js API such as `next/headers`). Importing one name from such a barrel drags the other's directive context across the React Server Components boundary, the documented Next.js App Router footgun. Type-only re-exports are ignored (erased at build), and a barrel re-exporting a client module alongside an ordinary undirected utility does NOT flag. To fix: split the barrel so client and server-only modules are re-exported from separate entry points. The check runs only when the project declares `next`.",
266        docs_path: "explanations/dead-code#mixed-client-server-barrels",
267    },
268    RuleDef {
269        id: "fallow/misplaced-directive",
270        category: "Policy",
271        name: "Misplaced directive",
272        short: "\"use client\" / \"use server\" directive is not in the leading position and is ignored",
273        full: "A `\"use client\"` or `\"use server\"` directive string appears as an expression statement after a non-directive statement (an `import`, a `const`). React Server Components bundlers only honor a directive in the leading prologue, before any other statement; once any statement precedes it the string is parsed as an ordinary expression and SILENTLY IGNORED. The intended client/server boundary never takes effect, so the file is treated as a server module. To fix: move the directive to the very top of the file, above every import. The check runs only when the project declares `next`.",
274        docs_path: "explanations/dead-code#misplaced-directives",
275    },
276    RuleDef {
277        id: "fallow/unprovided-inject",
278        category: "Dead code",
279        name: "Unprovided injects",
280        short: "inject() / getContext() reads a key that no provide() / setContext() supplies",
281        full: "A Vue `inject(KEY)` or Svelte `getContext(KEY)` reads a dependency-injection key (an imported or module-local symbol) that no matching `provide(KEY)` / `setContext(KEY)` supplies anywhere in the project. The read resolves to undefined at runtime, surfaced only at render. To fix: add a matching provider for the key, or remove the dead inject. Defaults to warn, not error: a provider may live outside the analyzed graph (an app-level provide registered elsewhere, a plugin, a host application). String-literal keys and keys imported from a package are abstained.",
282        docs_path: "explanations/dead-code#unprovided-injects",
283    },
284    RuleDef {
285        id: "fallow/unrendered-component",
286        category: "Dead code",
287        name: "Unrendered components",
288        short: "A Vue / Svelte component is reachable through a barrel but rendered nowhere",
289        full: "A Vue or Svelte single-file component (the default export of a `.vue` / `.svelte` file) is reachable in the module graph (a barrel re-exports it) but instantiated NOWHERE in the project: no `<Tag>`, no `:is` / `this=` binding, no `components` / `app.component` registration, no `h()` / auto-import use, and no script value-read. It survives unused-file (the barrel keeps it reachable) and unused-export (the re-export counts as a use), yet no file actually renders it. To fix: render the component somewhere, or delete it and drop the dead re-export. Defaults to warn, not error: a component can be rendered reflectively (a dynamic `<component :is>` resolved from a non-literal value), so analyzer confidence is lower. Components that are themselves entry points (route pages, layouts, `App.vue`) and components re-exported from a non-private package entry point are abstained.",
290        docs_path: "explanations/dead-code#unrendered-components",
291    },
292    RuleDef {
293        id: "fallow/unused-component-prop",
294        category: "Dead code",
295        name: "Unused component props",
296        short: "A Vue, Svelte, or React component prop is referenced nowhere in its own component",
297        full: "A declared component prop referenced nowhere inside its own component, in these framework shapes: a Vue `<script setup>` defineProps prop, a Svelte 5 `$props()` prop, or a React/Preact prop destructured from a component's first parameter and read nowhere in its body. Framework type checkers check caller-side prop correctness, not this in-component dead-input direction. Conservative: Vue abstains on `$attrs` fallthrough, whole-object props use, defineExpose, defineModel, and imported prop-type aliases; Svelte abstains on rest, computed, nested, and whole-object `$props()` shapes; React abstains on rest spread (`{...rest}`), props forwarded by spread, props passed wholesale to a hook, `forwardRef` / imported-interface props, and exported public-API component props. Default warn; suppress or remove the prop.",
298        docs_path: "explanations/dead-code#unused-component-props",
299    },
300    RuleDef {
301        id: "fallow/unused-component-emit",
302        category: "Dead code",
303        name: "Unused component emits",
304        short: "A Vue <script setup> defineEmits event is emitted nowhere in its own component",
305        full: "A Vue `<script setup>` defineEmits declared event that is emitted nowhere in its own component (no `emit('<name>')` call). vue-tsc / Volar check caller-side emit correctness, not this in-component dead-output direction. Conservative: abstains on `$attrs` fallthrough, whole-object emit use, defineExpose, defineModel, and imported emit-type aliases. Default warn; suppress or remove the emit.",
306        docs_path: "explanations/dead-code#unused-component-emits",
307    },
308    RuleDef {
309        id: "fallow/unused-component-input",
310        category: "Dead code",
311        name: "Unused component inputs",
312        short: "An Angular @Input() / signal input() / model() input is read nowhere in its own component",
313        full: "An Angular `@Input()` / signal `input()` / `model()` declared input that is read nowhere in its own component (neither the inline / external template nor the class body). The Angular compiler never flags a declared-but-unread `@Input`, and there is no `@angular-eslint` rule for it. Conservative: usage detection over-credits by design (a template sentinel ref, any class-body member access by that name, or a bare identifier read counts as used), and the whole component abstains on an unresolved `extends` heritage clause (a base class in another file may read the input). A `model()` is recorded as an input only. Default warn; suppress or remove the input. The check runs only when the project declares `@angular/core`.",
314        docs_path: "explanations/dead-code#unused-component-inputs",
315    },
316    RuleDef {
317        id: "fallow/unused-component-output",
318        category: "Dead code",
319        name: "Unused component outputs",
320        short: "An Angular @Output() / signal output() output is emitted nowhere in its own component",
321        full: "An Angular `@Output()` / signal `output()` declared output that is emitted nowhere in its own component (no `this.<output>.emit(...)`). The Angular compiler never flags a declared-but-unemitted `@Output`, and there is no `@angular-eslint` rule for it. Conservative: usage detection over-credits by design (a `this.<output>.emit` call site, or any value read of `this.<output>` that might forward it, counts as used), and the whole component abstains on an unresolved `extends` heritage clause. A `model()`-derived implicit output is never flagged. Default warn; suppress or remove the output. The check runs only when the project declares `@angular/core`.",
322        docs_path: "explanations/dead-code#unused-component-outputs",
323    },
324    RuleDef {
325        id: "fallow/unused-svelte-event",
326        category: "Dead code",
327        name: "Unused Svelte events",
328        short: "A Svelte component dispatches a createEventDispatcher event whose name is listened to nowhere in the project",
329        full: "A Svelte component that dispatches a custom event via `createEventDispatcher` (`const dispatch = createEventDispatcher(); dispatch('save')`) whose event name is listened to NOWHERE in the analyzed project. This is the cross-file dead-OUTPUT direction: the component fires an event nothing handles. No native tool covers the listener side: eslint-plugin-svelte and svelte-check are single-file / type-only. fallow builds a project-wide listened-event set from every component-tag `on:<name>` binding (event forwarding, an `on:<name>` with no handler, counts as a listen), then flags a dispatched event whose name is in no listened set. Conservative (zero false positives): the whole component abstains on a dynamic `dispatch(<nonLiteral>)` (the event name is unknowable) or a `dispatch` reference forwarded as a value; a DOM `on:click` on a lowercase element is NOT a custom event and is ignored; and any listener on any component anywhere credits the name (the liberal over-credit, false-negative-safe direction). Default warn; remove the dispatched event or wire a listener. The check runs only when the project declares `svelte`.",
330        docs_path: "explanations/dead-code#unused-svelte-events",
331    },
332    RuleDef {
333        id: "fallow/unused-server-action",
334        category: "Dead code",
335        name: "Unused server actions",
336        short: "A Next.js Server Action exported from a \"use server\" file is referenced by no code in the project",
337        full: "A Next.js Server Action (an export of a `\"use server\"` file) that no code in the project references: no import-and-call, no `action={fn}` JSX binding, no `<form action={fn}>`. This is the cross-graph \"declared but zero consumers\" direction, reclassified out of `unused-export` for `\"use server\"` files so the finding carries the action-specific signal. eslint-plugin-next is single-file and cannot see cross-file usage. It does NOT mean the endpoint is unreachable: Next.js still registers a generated action id, so it stays POST-able; it means no project code references it (likely forgotten or dead, and a candidate for removal to shrink surface area). Default warn; wire the action to a consumer or remove it. The check runs only when the project declares `next`.",
338        docs_path: "explanations/dead-code#unused-server-actions",
339    },
340    RuleDef {
341        id: "fallow/unused-load-data-key",
342        category: "Dead code",
343        name: "Unused load data keys",
344        short: "A SvelteKit load() return-object key is read by no consumer",
345        full: "A SvelteKit route `load()` (in `+page.ts` / `+page.server.ts` and the `.js` variants) returns an object whose keys become the route's `data` prop. A returned key that NO consumer reads is dead: it runs a real server-side fetch / DB cost on every request for data nothing renders. fallow checks two channels: the sibling `+page.svelte`'s `data.<key>` reads (route-pinned), and project-wide `page.data.<key>` (Svelte 5 `$app/state`) / `$page.data.<key>` (Svelte 4 `$app/stores`) reads in any component. `svelte-check` types `data` via generated `$types` but never flags an unread RETURNED key. The detector abstains (never false-flags) on a spread / non-literal / multi-return / computed-key / wrapped `load`, on a sibling that passes the whole `data` object opaquely, on a `+page.server.ts` whose universal `+page.ts` sibling forwards its `data`, and project-wide when any whole-object use of `page.data` / `$page.data` is seen. Default warn; delete the key or wire a consumer. A load fetch can have side effects, so there is no safe auto-fix. The check runs only when the project declares `@sveltejs/kit`.",
346        docs_path: "explanations/dead-code#unused-load-data-keys",
347    },
348    RuleDef {
349        id: "fallow/prop-drilling",
350        category: "Dead code",
351        name: "Prop drilling",
352        short: "A React/Preact prop is forwarded unchanged through 3+ pass-through components to a distant consumer",
353        full: "A React/Preact prop is received by a component, forwarded UNCHANGED to a child, and forwarded again through two or more intermediate \"pass-through\" components until a component that substantively uses it. The high-confidence signal is that the received identifier appears ONLY as the root of forwarded child-JSX attribute values (so `<Child userName={user.name}/>` counts: the prop `user` is projected forward), not the attribute name matching. fallow emits located per-chain records (the source, each pass-through hop, and the consumer with file + line + component name) so CI and an agent can act: colocate the consumer with the data, lift the value to a React context/provider at a mid-chain hop, or compose the component so the intermediates no longer thread the prop. This is a graph-derived health signal, not a correctness error. The rule defaults to OFF (opt-in), like private-type-leak and the security rules: enable it with `prop-drilling: \"warn\"` in `rules`. Zero false positives by construction: any `{...props}` spread, `cloneElement`, element-as-prop / render-prop / children-as-function, or context `*.Provider` anywhere in the chain abstains the whole chain, as does an ambiguous or unresolvable hop. The check runs only when the project declares `react` / `react-dom` / `next` / `preact`.",
354        docs_path: "explanations/dead-code#prop-drilling",
355    },
356    RuleDef {
357        id: "fallow/thin-wrapper",
358        category: "Dead code",
359        name: "Thin wrapper",
360        short: "A React/Preact component whose whole body is a single spread-forwarded child render (a candidate for inlining)",
361        full: "A React/Preact component whose ENTIRE body is structural indirection: it returns exactly one capitalized component element that forwards the component's own props via a bare spread (`return <Child {...props}/>`), with no host-element wrapper, no extra children, no named attributes alongside the spread, no hooks, no branching, and no other statements. Such a component adds nothing of its own: it is a CANDIDATE for inlining at its call sites or deleting, not a correctness error. fallow emits a located per-wrapper record (file + line + the wrapper and child component names) so CI and an agent can act. The rule defaults to OFF (opt-in), like prop-drilling and the security rules: enable it with `thin-wrapper: \"warn\"` in `rules`. Zero false positives by construction: a `forwardRef` / `memo` wrapper (the sanctioned way to make a child ref-able or set a perf boundary), an EXPORTED component (a public-API re-brand / encapsulation), a context `*.Provider` wrapper, a `cloneElement` / render-prop forward, a wrapper that passes ANY named attribute alongside the spread (a fixed configuration), a self-render, or an unresolvable / member-expression child all abstain. A TypeScript-only type-narrowing wrapper (`const StrictButton = (p: StrictProps) => <Button {...p}/>`) is a known limitation under ADR-001's syntactic analysis; suppress it with the inline comment. The check runs only when the project declares `react` / `react-dom` / `next` / `preact`.",
362        docs_path: "explanations/dead-code#thin-wrapper",
363    },
364    RuleDef {
365        id: "fallow/duplicate-prop-shape",
366        category: "Dead code",
367        name: "Duplicate prop shape",
368        short: "Three or more React/Preact components across two or more files declare an identical prop-name set (a missing shared Props type)",
369        full: "Three or more distinct React/Preact components, living in two or more files, whose statically-harvested prop NAME set is byte-for-byte IDENTICAL after (a) excluding a fixed denylist of ubiquitous DOM / render-passthrough prop names (className, style, id, children, key, ref, the common event handlers, plus data-* / aria-* by prefix) and (b) requiring the REMAINING significant set to have four or more members. Identity is over NAMES only, never types (ADR-001 cannot resolve types). This is a structural-refactor health signal: the recurring shape is a missing shared abstraction, so extract one shared `Props` type (or a base component) that every member reuses. It is never a correctness error and never an auto-fix. fallow emits one located record per participating component, each naming the shared `shape`, the `group_size`, and the OTHER members in `sharing_components`. The rule defaults to OFF (opt-in), like thin-wrapper and the security rules: enable it with `duplicate-prop-shape: \"warn\"` in `rules`. Anti-noise gates (defended as rule-of-three plus a denylist-survivor floor, not tuned magic): the four-significant-prop floor turns `{label, onClick}` buttons into non-findings; the three-component floor is the rule-of-three abstraction trigger; the two-file floor keeps a local same-shaped variant pair (a render-prop pair, a Foo/FooImpl split) unflagged. A component whose props are not fully harvestable (a rest/spread signature, a forwardRef/memo over an imported interface) ABSTAINS, because a partial prop set can never be proven identical. Exact full-set identity ONLY: a superset / subset relationship does NOT group, so a four-prop group and a five-prop superset form TWO findings (the price of zero invalid groups: the finding always fits one extracted shared type). The check runs only when the project declares `react` / `react-dom` / `next` / `preact`.",
370        docs_path: "explanations/dead-code#duplicate-prop-shape",
371    },
372    RuleDef {
373        id: "fallow/route-collision",
374        category: "Policy",
375        name: "Route collision",
376        short: "Two or more Next.js App Router route files resolve to the same URL",
377        full: "Two or more App Router route files (a `page` or a `route` handler) resolve to the SAME URL within one app-root. Route groups `(name)` and parallel slots `@name` do not change the URL, so `app/(marketing)/about/page.tsx` and `app/(shop)/about/page.tsx` both own `/about`. Next.js fails the build (\"You cannot have two parallel pages that resolve to the same path\") because a URL can have at most one owner, whether a Page or a Route Handler. fallow surfaces every colliding file at once; the build error names only one. Buckets are scoped per app-root (per workspace package), so a monorepo with several independent Next apps sharing a path is not flagged. Files under a private `_folder` or an intercepting marker `(.)`/`(..)`/`(...)` are excluded. There is no safe auto-fix: move or merge one of the files so each URL has a single owner. The check runs only when the project declares `next`.",
378        docs_path: "explanations/dead-code#route-collisions",
379    },
380    RuleDef {
381        id: "fallow/dynamic-segment-name-conflict",
382        category: "Policy",
383        name: "Dynamic segment name conflict",
384        short: "Sibling Next.js dynamic route segments use different slug names at the same position",
385        full: "Two or more sibling dynamic route segments at the same App Router tree position use different param spellings (`[id]` vs `[slug]`, or a catch-all `[...x]` vs an optional catch-all `[[...x]]`). Next.js throws \"You cannot use different slug names for the same dynamic path\" at dev and production runtime when the position is hit, because one position must resolve to a single param name. `next build` does NOT catch this (the build succeeds), so CI passes while the route crashes on its first request; fallow's static catch closes that gap. Route groups are transparent to the position and parallel slots fork it, so only genuinely-sibling segments conflict. To fix: rename the dynamic segments at the position to one consistent slug name. The check runs only when the project declares `next`.",
386        docs_path: "explanations/dead-code#dynamic-segment-name-conflicts",
387    },
388];
389
390/// Look up a rule definition by its SARIF rule ID across all rule sets.
391#[must_use]
392pub fn rule_by_id(id: &str) -> Option<&'static RuleDef> {
393    CHECK_RULES
394        .iter()
395        .chain(HEALTH_RULES.iter())
396        .chain(DUPES_RULES.iter())
397        .chain(FLAGS_RULES.iter())
398        .chain(SECURITY_RULES.iter())
399        .find(|r| r.id == id)
400}
401
402/// Build the docs URL for a rule.
403#[must_use]
404pub fn rule_docs_url(rule: &RuleDef) -> String {
405    format!("{DOCS_BASE}/{}", rule.docs_path)
406}
407
408/// Extra educational content for the standalone `fallow explain <issue-type>`
409/// command. Kept separate from [`RuleDef`] so SARIF and `_meta` payloads remain
410/// compact while terminal users and agents can ask for worked examples on
411/// demand.
412pub struct RuleGuide {
413    pub example: &'static str,
414    pub how_to_fix: &'static str,
415}
416
417/// Look up an issue type from a user-facing token.
418///
419/// Accepts canonical SARIF ids (`fallow/unused-export`), issue tokens
420/// (`unused-export`), and common CLI filter spellings (`unused-exports`).
421#[must_use]
422pub fn rule_by_token(token: &str) -> Option<&'static RuleDef> {
423    let trimmed = token.trim();
424    if trimmed.is_empty() {
425        return None;
426    }
427    if let Some(rule) = rule_by_id(trimmed) {
428        return Some(rule);
429    }
430    let normalized = trimmed
431        .strip_prefix("fallow/")
432        .unwrap_or(trimmed)
433        .trim_start_matches("--")
434        .replace('_', "-")
435        .split_whitespace()
436        .collect::<Vec<_>>()
437        .join("-");
438    let alias = dead_code_alias_id(&normalized)
439        .or_else(|| catalog_alias_id(&normalized))
440        .or_else(|| health_alias_id(&normalized))
441        .or_else(|| security_alias_id(&normalized));
442    if let Some(id) = alias
443        && let Some(rule) = rule_by_id(id)
444    {
445        return Some(rule);
446    }
447    let security_token = normalized.strip_prefix("security-").unwrap_or(&normalized);
448    let security_id = format!("security/{security_token}");
449    if let Some(rule) = rule_by_id(&security_id) {
450        return Some(rule);
451    }
452    let singular = normalized
453        .strip_suffix('s')
454        .filter(|_| normalized != "unused-class")
455        .unwrap_or(&normalized);
456    let singular_security_token = singular.strip_prefix("security-").unwrap_or(singular);
457    let singular_security_id = format!("security/{singular_security_token}");
458    if let Some(rule) = rule_by_id(&singular_security_id) {
459        return Some(rule);
460    }
461    let id = format!("fallow/{singular}");
462    rule_by_id(&id).or_else(|| {
463        CHECK_RULES
464            .iter()
465            .chain(HEALTH_RULES.iter())
466            .chain(DUPES_RULES.iter())
467            .chain(FLAGS_RULES.iter())
468            .chain(SECURITY_RULES.iter())
469            .find(|rule| {
470                rule.docs_path.ends_with(&normalized)
471                    || rule.docs_path.ends_with(singular)
472                    || rule.name.eq_ignore_ascii_case(trimmed)
473            })
474    })
475}
476
477fn dead_code_alias_id(normalized: &str) -> Option<&'static str> {
478    match normalized {
479        "unused-files" => Some("fallow/unused-file"),
480        "unused-exports" => Some("fallow/unused-export"),
481        "unused-types" => Some("fallow/unused-type"),
482        "private-type-leaks" => Some("fallow/private-type-leak"),
483        "unused-deps" | "unused-dependencies" => Some("fallow/unused-dependency"),
484        "unused-dev-deps" | "unused-dev-dependencies" => Some("fallow/unused-dev-dependency"),
485        "unused-optional-deps" | "unused-optional-dependencies" => {
486            Some("fallow/unused-optional-dependency")
487        }
488        "type-only-deps" | "type-only-dependencies" => Some("fallow/type-only-dependency"),
489        "test-only-deps" | "test-only-dependencies" => Some("fallow/test-only-dependency"),
490        "unused-enum-members" => Some("fallow/unused-enum-member"),
491        "unused-class-members" => Some("fallow/unused-class-member"),
492        "unused-store-members" => Some("fallow/unused-store-member"),
493        "unprovided-injects" | "unprovided-inject" => Some("fallow/unprovided-inject"),
494        "unrendered-components" | "unrendered-component" => Some("fallow/unrendered-component"),
495        "unused-component-props" | "unused-component-prop" => Some("fallow/unused-component-prop"),
496        "unused-component-emits" | "unused-component-emit" => Some("fallow/unused-component-emit"),
497        "unused-component-inputs" | "unused-component-input" => {
498            Some("fallow/unused-component-input")
499        }
500        "unused-component-outputs" | "unused-component-output" => {
501            Some("fallow/unused-component-output")
502        }
503        "unused-svelte-events" | "unused-svelte-event" => Some("fallow/unused-svelte-event"),
504        "unused-server-actions" | "unused-server-action" => Some("fallow/unused-server-action"),
505        "unused-load-data-keys" | "unused-load-data-key" => Some("fallow/unused-load-data-key"),
506        "prop-drilling" => Some("fallow/prop-drilling"),
507        "thin-wrapper" | "thin-wrappers" => Some("fallow/thin-wrapper"),
508        "duplicate-prop-shape" | "duplicate-prop-shapes" => Some("fallow/duplicate-prop-shape"),
509        "unresolved-imports" => Some("fallow/unresolved-import"),
510        "unlisted-deps" | "unlisted-dependencies" => Some("fallow/unlisted-dependency"),
511        "duplicate-exports" => Some("fallow/duplicate-export"),
512        "circular-deps" | "circular-dependencies" => Some("fallow/circular-dependency"),
513        "boundary-violations" => Some("fallow/boundary-violation"),
514        "boundary-coverage" | "boundary-coverage-violations" => Some("fallow/boundary-coverage"),
515        "boundary-calls" | "boundary-call-violations" => Some("fallow/boundary-call-violation"),
516        "policy-violation" | "policy-violations" => Some("fallow/policy-violation"),
517        "stale-suppressions" => Some("fallow/stale-suppression"),
518        "missing-suppression-reason" | "missing-suppression-reasons" => {
519            Some("fallow/missing-suppression-reason")
520        }
521        _ => None,
522    }
523}
524
525fn catalog_alias_id(normalized: &str) -> Option<&'static str> {
526    match normalized {
527        "unused-catalog-entries" | "unused-catalog-entry" | "catalog" => {
528            Some("fallow/unused-catalog-entry")
529        }
530        "empty-catalog-groups" | "empty-catalog-group" | "empty-catalog" => {
531            Some("fallow/empty-catalog-group")
532        }
533        "unresolved-catalog-references" | "unresolved-catalog-reference" | "unresolved-catalog" => {
534            Some("fallow/unresolved-catalog-reference")
535        }
536        "unused-dependency-overrides"
537        | "unused-dependency-override"
538        | "unused-override"
539        | "unused-overrides" => Some("fallow/unused-dependency-override"),
540        "misconfigured-dependency-overrides"
541        | "misconfigured-dependency-override"
542        | "misconfigured-override"
543        | "misconfigured-overrides" => Some("fallow/misconfigured-dependency-override"),
544        _ => None,
545    }
546}
547
548fn health_alias_id(normalized: &str) -> Option<&'static str> {
549    match normalized {
550        "complexity" | "high-complexity" => Some("fallow/high-complexity"),
551        "cyclomatic" | "high-cyclomatic" | "high-cyclomatic-complexity" => {
552            Some("fallow/high-cyclomatic-complexity")
553        }
554        "cognitive" | "high-cognitive" | "high-cognitive-complexity" => {
555            Some("fallow/high-cognitive-complexity")
556        }
557        "crap" | "high-crap" | "high-crap-score" => Some("fallow/high-crap-score"),
558        "duplication" | "dupes" | "code-duplication" => Some("fallow/code-duplication"),
559        "feature-flag" | "feature-flags" | "flags" => Some("fallow/feature-flag"),
560        _ => None,
561    }
562}
563
564fn security_alias_id(normalized: &str) -> Option<&'static str> {
565    match normalized {
566        "security"
567        | "security-candidate"
568        | "security-candidates"
569        | "tainted-sink"
570        | "tainted-sinks"
571        | "security-sink"
572        | "security-sinks" => Some("security/tainted-sink"),
573        "client-server-leak"
574        | "client-server-leaks"
575        | "security-client-server-leak"
576        | "security-client-server-leaks" => Some("security/client-server-leak"),
577        "hardcoded-secret" | "hardcoded-secrets" | "hard-coded-secret" | "hard-coded-secrets" => {
578            Some("security/hardcoded-secret")
579        }
580        _ => None,
581    }
582}
583
584/// Return worked-example and fix guidance for a rule.
585#[must_use]
586pub fn rule_guide(rule: &RuleDef) -> RuleGuide {
587    source_dead_code_rule_guide(rule.id)
588        .or_else(|| member_import_rule_guide(rule.id))
589        .or_else(|| architecture_rule_guide(rule.id))
590        .or_else(|| catalog_rule_guide(rule.id))
591        .or_else(|| health_runtime_rule_guide(rule.id))
592        .or_else(|| duplication_rule_guide(rule.id))
593        .or_else(|| security_rule_guide(rule.id))
594        .unwrap_or_else(fallback_rule_guide)
595}
596
597fn source_dead_code_rule_guide(id: &str) -> Option<RuleGuide> {
598    Some(match id {
599        "fallow/unused-file" => RuleGuide {
600            example: "src/old-widget.ts is not imported by any entry point, route, script, or config file.",
601            how_to_fix: "Delete the file if it is genuinely dead. If a framework loads it implicitly, add the right plugin/config pattern or mark it in alwaysUsed.",
602        },
603        "fallow/unused-export" => RuleGuide {
604            example: "export const formatPrice = ... exists in src/money.ts, but no module imports formatPrice.",
605            how_to_fix: "Remove the export or make it file-local. If it is public API, import it from an entry point or add an intentional suppression with context.",
606        },
607        "fallow/unused-type" => RuleGuide {
608            example: "export interface LegacyProps is exported, but no module imports the type.",
609            how_to_fix: "Remove the type export, inline it, or keep it behind an explicit API entry point when consumers rely on it.",
610        },
611        "fallow/private-type-leak" => RuleGuide {
612            example: "export function makeUser(): InternalUser exposes InternalUser even though InternalUser is not exported.",
613            how_to_fix: "Export the referenced type, change the public signature to an exported type, or keep the helper private.",
614        },
615        "fallow/unused-dependency"
616        | "fallow/unused-dev-dependency"
617        | "fallow/unused-optional-dependency" => RuleGuide {
618            example: "package.json lists left-pad, but no source, script, config, or plugin-recognized file imports it.",
619            how_to_fix: "Remove the dependency after checking runtime/plugin usage. If another workspace uses it, move the dependency to that workspace.",
620        },
621        "fallow/type-only-dependency" => RuleGuide {
622            example: "zod is in dependencies but only appears in import type declarations.",
623            how_to_fix: "Move the package to devDependencies unless runtime code imports it as a value.",
624        },
625        "fallow/test-only-dependency" => RuleGuide {
626            example: "vitest is listed in dependencies, but only test files import it.",
627            how_to_fix: "Move the package to devDependencies unless production code imports it at runtime.",
628        },
629        _ => return None,
630    })
631}
632
633fn member_import_rule_guide(id: &str) -> Option<RuleGuide> {
634    Some(match id {
635        "fallow/unused-enum-member" => RuleGuide {
636            example: "Status.Legacy remains in an exported enum, but no code reads that member.",
637            how_to_fix: "Remove the member after checking serialized/API compatibility, or suppress it with a reason when external data still uses it.",
638        },
639        "fallow/unused-class-member" => RuleGuide {
640            example: "class Parser has a public parseLegacy method that is never called in the project.",
641            how_to_fix: "Remove or privatize the member. For reflection/framework lifecycle hooks, configure or suppress the intentional entry point.",
642        },
643        "fallow/unused-store-member" => RuleGuide {
644            example: "useCartStore declares a discountTotal getter that no component, composable, or other store ever reads.",
645            how_to_fix: "Remove the unused state property, getter, or action. If it is consumed reflectively (a Pinia plugin, $onAction, or dynamic dispatch), suppress the line with // fallow-ignore-next-line unused-store-member.",
646        },
647        "fallow/unprovided-inject" => RuleGuide {
648            example: "A component calls inject(ThemeKey) (Vue) or getContext(ThemeKey) (Svelte) with an imported symbol key, but no provide(ThemeKey) / setContext(ThemeKey) exists anywhere in the project.",
649            how_to_fix: "Add a matching provide() / setContext() for the key, or remove the dead inject() / getContext(). If a provider lives outside the analyzed graph (an app-level provide registered elsewhere, a plugin, a host app), suppress the line with // fallow-ignore-next-line unprovided-inject.",
650        },
651        "fallow/unrendered-component" => RuleGuide {
652            example: "components/Orphan.vue is re-exported from a barrel (export { default as Orphan } from './Orphan.vue') but no template, registration, h() call, or dynamic import ever renders it.",
653            how_to_fix: "Render the component where it belongs, or delete it and remove the dead barrel re-export. If it is rendered reflectively (a dynamic <component :is> from a non-literal value), suppress the line with // fallow-ignore-next-line unrendered-component.",
654        },
655        "fallow/unused-component-prop" => RuleGuide {
656            example: "Widget.vue declares defineProps<{ size: string }>(), or a React Widget({ size }) destructures `size`, but `size` is referenced nowhere in the component (Vue: its script or template; React: its function body or JSX).",
657            how_to_fix: "Remove the unused prop, or reference it in the component (Vue: the script / template; React: the function body or JSX). If the prop is part of a deliberately-stable public component API, suppress the line with // fallow-ignore-next-line unused-component-prop.",
658        },
659        "fallow/unused-component-emit" => RuleGuide {
660            example: "Widget.vue declares defineEmits<{ close: [] }>() but `emit('close')` is called nowhere in the component's script.",
661            how_to_fix: "Remove the unused emit, or emit it in the script. If the emit is part of a deliberately-stable public component API, suppress the line with // fallow-ignore-next-line unused-component-emit.",
662        },
663        "fallow/unused-component-input" => RuleGuide {
664            example: "user-card.component.ts declares @Input() size: string (or size = input<string>()) but `size` is read nowhere in the template or the class body.",
665            how_to_fix: "Remove the unused input, or read it in the template or class body. If the input is part of a deliberately-stable public component API, suppress the line with // fallow-ignore-next-line unused-component-input.",
666        },
667        "fallow/unused-component-output" => RuleGuide {
668            example: "user-card.component.ts declares @Output() close = new EventEmitter<void>() (or close = output<void>()) but `this.close.emit(...)` is called nowhere in the class.",
669            how_to_fix: "Remove the unused output, or emit it from the class. If the output is part of a deliberately-stable public component API, suppress the line with // fallow-ignore-next-line unused-component-output.",
670        },
671        "fallow/unused-svelte-event" => RuleGuide {
672            example: "Child.svelte calls const dispatch = createEventDispatcher(); dispatch('dead'), but no parent listens for it (no <Child on:dead> anywhere in the project).",
673            how_to_fix: "Remove the dispatched event, or listen for it on the component (<Child on:dead={...}> or forward it via <Child on:dead>). If the event is dispatched reflectively (a dynamic name) or is part of a deliberately-stable public component API, suppress the line with // fallow-ignore-next-line unused-svelte-event.",
674        },
675        "fallow/unused-server-action" => RuleGuide {
676            example: "app/actions.ts has \"use server\" and exports submitForm, but no component imports it, binds it via action={submitForm}, or uses it in <form action={submitForm}>.",
677            how_to_fix: "Wire the action to a consumer (an import-and-call, an action={fn} binding, or a <form action={fn}>), or remove it. If it is invoked reflectively (an action registry dispatching by id, or a non-JS caller), suppress the line with // fallow-ignore-next-line unused-server-action.",
678        },
679        "fallow/unused-load-data-key" => RuleGuide {
680            example: "src/routes/blog/+page.ts returns { posts, draftCount } but +page.svelte only reads data.posts and no component reads page.data.draftCount.",
681            how_to_fix: "Delete the unused key from the load() return (and skip its fetch), or wire a consumer (read data.<key> in +page.svelte, or page.data.<key> in a shared component). If the load fetch has a side effect you must keep, suppress the line with // fallow-ignore-next-line unused-load-data-key.",
682        },
683        "fallow/prop-drilling" => RuleGuide {
684            example: "Page receives `user` and renders <Layout user={user}/>; Layout only re-passes it to <Sidebar user={user}/>; Sidebar only re-passes it to <Profile user={user}/>, which finally reads user.name. The prop is drilled through Layout and Sidebar untouched.",
685            how_to_fix: "Collapse the chain: colocate the consumer with the data, lift the value into a React context/provider at a mid-chain hop and consume it there, or compose the component (pass the rendered child as children) so the intermediates no longer thread the prop. Enable the rule with rules.prop-drilling = \"warn\" (it defaults to off). To accept one chain, suppress the source prop with // fallow-ignore-next-line prop-drilling.",
686        },
687        "fallow/thin-wrapper" => RuleGuide {
688            example: "const ButtonWrapper = (props) => <Button {...props}/>; the wrapper has no own markup, hooks, or logic, so it only re-points at Button.",
689            how_to_fix: "Inline the wrapper at its call sites (use <Button .../> directly) or delete it. Keep it only if it is a deliberate seam (a planned divergence point, a public-API re-brand): an exported wrapper already abstains. Enable the rule with rules.thin-wrapper = \"warn\" (it defaults to off). To accept one wrapper, suppress it with // fallow-ignore-next-line thin-wrapper above the component definition.",
690        },
691        "fallow/duplicate-prop-shape" => RuleGuide {
692            example: "FieldText, FieldNumber, and FieldSelect (across three files) each declare exactly { name, label, value, onChange, error }. The five significant prop names are identical, so they form one duplicate-prop-shape group.",
693            how_to_fix: "Extract one shared Props type (e.g. type FieldProps = { name; label; value; onChange; error }) that every member reuses, or a base component the variants compose. Keep them separate only if a per-variant prop divergence is planned. Enable the rule with rules.duplicate-prop-shape = \"warn\" (it defaults to off). To accept one member, suppress it with // fallow-ignore-next-line duplicate-prop-shape above the component definition; the suppressed member still appears in its siblings' sharing_components because the group is real regardless of suppression.",
694        },
695        "fallow/unresolved-import" => RuleGuide {
696            example: "src/app.ts imports ./routes/admin, but no matching file exists after extension and index resolution.",
697            how_to_fix: "Fix the specifier, restore the missing file, install the package, or align tsconfig path aliases with the runtime resolver.",
698        },
699        "fallow/unlisted-dependency" => RuleGuide {
700            example: "src/api.ts imports undici, but the nearest package.json does not list undici.",
701            how_to_fix: "Add the package to dependencies/devDependencies in the workspace that imports it instead of relying on hoisting or transitive deps.",
702        },
703        "fallow/duplicate-export" => RuleGuide {
704            example: "Button is exported from both src/ui/button.ts and src/components/button.ts.",
705            how_to_fix: "Rename or consolidate the exports so consumers have one intentional import target.",
706        },
707        _ => return None,
708    })
709}
710
711fn architecture_rule_guide(id: &str) -> Option<RuleGuide> {
712    Some(match id {
713        "fallow/circular-dependency" => RuleGuide {
714            example: "src/a.ts imports src/b.ts, and src/b.ts imports src/a.ts.",
715            how_to_fix: "Extract shared code to a third module, invert the dependency, or split initialization-time side effects from type-only contracts.",
716        },
717        "fallow/boundary-violation" => RuleGuide {
718            example: "features/billing imports app/admin even though the configured boundary only allows imports from shared and entities.",
719            how_to_fix: "Move the shared contract to an allowed zone, invert the dependency, or update the boundary config only if the architecture rule was wrong.",
720        },
721        "fallow/boundary-coverage" => RuleGuide {
722            example: "src/generated/client.ts is reachable but does not match any boundaries.zones[].patterns entry.",
723            how_to_fix: "Add the file to the intended zone pattern, move it under a zoned directory, or add a generated-file glob to boundaries.coverage.allowUnmatched.",
724        },
725        "fallow/boundary-call-violation" => RuleGuide {
726            example: "src/domain/policy.ts calls execSync from node:child_process while boundaries.calls.forbidden bans child_process.* from the domain zone.",
727            how_to_fix: "Move the call into a zone that may perform the effect, route it through an allowed abstraction, or narrow the forbidden pattern if the rule was wrong. To suppress, use the boundary family token: `// fallow-ignore-next-line boundary-violation` governs import, coverage, and call findings alike (the rule-id-shaped `boundary-call-violation` is accepted as an alias).",
728        },
729        "fallow/policy-violation" => RuleGuide {
730            example: "src/app.ts imports moment while a rule pack bans the moment specifier with the message 'Use date-fns.'",
731            how_to_fix: "Replace the banned call, import, or effectful usage with the alternative named in the rule's message. To waive one rule, use `// fallow-ignore-next-line policy-violation:<pack>/<rule-id>` or the file-level form. Use bare `policy-violation` only when you intend to suppress every rule-pack finding at that scope.",
732        },
733        "fallow/stale-suppression" => RuleGuide {
734            example: "// fallow-ignore-next-line unused-export remains above an export that is now used.",
735            how_to_fix: "Remove the suppression. If a different issue is still intentional, replace it with a current, specific suppression.",
736        },
737        "fallow/missing-suppression-reason" => RuleGuide {
738            example: "// fallow-ignore-next-line unused-export appears without the required explanatory reason.",
739            how_to_fix: "Add a concise reason after the suppression token, or remove the suppression if the issue is no longer intentional.",
740        },
741        _ => return None,
742    })
743}
744
745fn catalog_rule_guide(id: &str) -> Option<RuleGuide> {
746    Some(match id {
747        "fallow/unused-catalog-entry" => RuleGuide {
748            example: "The catalog source declares `catalog: { is-even: ^1.0.0 }`, but no workspace package.json declares `\"is-even\": \"catalog:\"`.",
749            how_to_fix: "Delete the entry from the catalog source file. If any consumer uses a hardcoded version (surfaced in `hardcoded_consumers`), switch that consumer to `catalog:` first to keep versions aligned.",
750        },
751        "fallow/empty-catalog-group" => RuleGuide {
752            example: "The catalog source declares `catalogs: { react17: {} }` after the last react17 entry was removed.",
753            how_to_fix: "Delete the empty named group from the catalog source file. Comments between the deleted header and the next sibling can stay in place for manual review.",
754        },
755        "fallow/unresolved-catalog-reference" => RuleGuide {
756            example: "packages/app/package.json declares `\"old-react\": \"catalog:react17\"`, but `catalogs.react17` in the catalog source does not declare `old-react`. The package manager install will fail.",
757            how_to_fix: "If `available_in_catalogs` is non-empty, change the reference to one of those catalogs (e.g. `catalog:react18`). Otherwise add the package to the named catalog in the catalog source, or remove the catalog reference and pin a hardcoded version. For staged migrations where the catalog edit lands separately, add the (package, catalog, consumer) triple to `ignoreCatalogReferences` in your fallow config.",
758        },
759        "fallow/unused-dependency-override" => RuleGuide {
760            example: "pnpm-workspace.yaml declares `overrides: { axios: ^1.6.0 }`, but no workspace package.json declares `axios` and `pnpm-lock.yaml` does not resolve it.",
761            how_to_fix: "Delete the entry from `pnpm-workspace.yaml` or `package.json#pnpm.overrides`. If the finding is caused by a stale or missing lockfile, refresh `pnpm-lock.yaml` and rerun fallow. If the override is intentionally retained, add it to `ignoreDependencyOverrides` in your fallow config.",
762        },
763        "fallow/misconfigured-dependency-override" => RuleGuide {
764            example: "pnpm-workspace.yaml declares `overrides: { \"@types/react@<<18\": \"18.0.0\" }`. The doubled `<<` is not a valid pnpm version selector and pnpm will reject the workspace at install time.",
765            how_to_fix: "Fix the key/value to match pnpm's override grammar: bare names (`axios`), scoped names (`@types/react`), targets with version selectors (`@types/react@<18`), parent matchers (`react>react-dom`), and parent chains with selectors on either side. Allowed value idioms: bare version range, `-` (delete), `$ref`, and `npm:alias`. If the entry was experimental, remove it.",
766        },
767        _ => return None,
768    })
769}
770
771fn health_runtime_rule_guide(id: &str) -> Option<RuleGuide> {
772    Some(match id {
773        "fallow/high-cyclomatic-complexity"
774        | "fallow/high-cognitive-complexity"
775        | "fallow/high-complexity" => RuleGuide {
776            example: "A function contains several nested conditionals, loops, and early exits, exceeding the configured complexity threshold. fallow also flags synthetic `<template>` findings on Angular .html templates and inline `@Component({ template: ... })` literals, and `<component>` rollup findings that combine the worst class method with its template.",
777            how_to_fix: "For function findings, extract named helpers, split independent branches, flatten guard clauses, and add tests around the behavior before refactoring. For `<template>` findings, split the template into child components, hoist data into the component class as computed signals, or replace nested `@if`/`@for` with a flatter structure. For `<component>` rollup findings, attack the larger half first; the per-half breakdown lives in `component_rollup`.",
778        },
779        "fallow/high-crap-score" => RuleGuide {
780            example: "A complex function has little or no matching Istanbul coverage, so its CRAP score crosses the configured gate.",
781            how_to_fix: "Add focused tests for the risky branches first, then simplify the function if the score remains high.",
782        },
783        "fallow/refactoring-target" => RuleGuide {
784            example: "A file combines high complexity density, churn, fan-in, and dead-code signals.",
785            how_to_fix: "Start with the listed evidence: remove dead exports, extract complex functions, then reduce fan-out or cycles in small steps.",
786        },
787        "fallow/untested-file" | "fallow/untested-export" => RuleGuide {
788            example: "Production-reachable code has no dependency path from discovered test entry points.",
789            how_to_fix: "Add or wire a test that imports the runtime path, or update entry-point/test discovery if the existing test is invisible to fallow.",
790        },
791        "fallow/runtime-safe-to-delete"
792        | "fallow/runtime-review-required"
793        | "fallow/runtime-low-traffic"
794        | "fallow/runtime-coverage-unavailable"
795        | "fallow/runtime-coverage" => RuleGuide {
796            example: "Runtime coverage shows a function was never called, barely called, or could not be matched during the capture window.",
797            how_to_fix: "Treat high-confidence cold static-dead code as delete candidates. For advisory or unavailable coverage, inspect seasonality, workers, source maps, and capture quality first.",
798        },
799        _ => return None,
800    })
801}
802
803fn duplication_rule_guide(id: &str) -> Option<RuleGuide> {
804    Some(match id {
805        "fallow/code-duplication" => RuleGuide {
806            example: "Two files contain the same normalized token sequence across a multi-line block.",
807            how_to_fix: "Extract the shared logic when the duplicated behavior should evolve together. Leave it duplicated when the similarity is accidental and likely to diverge.",
808        },
809        _ => return None,
810    })
811}
812
813fn security_rule_guide(id: &str) -> Option<RuleGuide> {
814    Some(match id {
815        "security/tainted-sink" => RuleGuide {
816            example: "A non-literal request field reaches a catalogue sink such as security/sql-injection or security/dangerous-html. The finding is a candidate, not proof of exploitability.",
817            how_to_fix: "Trace the source, sink, sanitization, and runtime context. Fix confirmed issues with parameterization, escaping, validation, or safer APIs, and suppress only reviewed false positives with context.",
818        },
819        "security/client-server-leak" => RuleGuide {
820            example: "A module marked `use client` imports code that reads a non-public `process.env` or `import.meta.env` value through a static path.",
821            how_to_fix: "Keep non-public env reads on the server side, move the value behind an API boundary, or rename only intentionally public values to the framework's public prefix.",
822        },
823        "security/hardcoded-secret" => RuleGuide {
824            example: "A provider-prefixed token-shaped literal is assigned to a secret-shaped variable, and the hardcoded-secret category is explicitly included.",
825            how_to_fix: "Rotate real credentials, move them to a secret manager or environment variable, and keep test-only literals clearly fake so they do not resemble provider tokens.",
826        },
827        id if id.starts_with("security/") => RuleGuide {
828            example: "A `fallow security` candidate uses this catalogue category as its SARIF rule id, for example security/sql-injection for a matched SQL sink.",
829            how_to_fix: "Review the candidate trace before acting. Confirm attacker control, missing sanitization, and reachable runtime context, then fix with the category-appropriate safer API or add a reviewed suppression.",
830        },
831        _ => return None,
832    })
833}
834
835fn fallback_rule_guide() -> RuleGuide {
836    RuleGuide {
837        example: "Run the relevant command with --format json --quiet --explain to inspect this rule in context.",
838        how_to_fix: "Use the issue action hints, source location, and docs URL to decide whether to remove, move, configure, or suppress the finding.",
839    }
840}
841
842/// Build the typed standalone explain output for a user-facing issue token.
843///
844/// # Errors
845///
846/// Returns a structured programmatic error when the token does not map to a
847/// registered rule.
848pub fn explain_issue_type(
849    issue_type: &str,
850) -> Result<fallow_output::ExplainOutput, crate::ProgrammaticError> {
851    let Some(rule) = rule_by_token(issue_type) else {
852        return Err(unknown_explain_error(issue_type));
853    };
854    let guide = rule_guide(rule);
855    Ok(fallow_output::ExplainOutput {
856        id: rule.id.to_string(),
857        name: rule.name.to_string(),
858        summary: rule.short.to_string(),
859        rationale: rule.full.to_string(),
860        example: guide.example.to_string(),
861        how_to_fix: guide.how_to_fix.to_string(),
862        docs: rule_docs_url(rule),
863    })
864}
865
866/// Serialize standalone explain output using the programmatic API contract.
867///
868/// # Errors
869///
870/// Returns a structured programmatic error for unknown rule tokens or JSON
871/// serialization failures.
872pub fn serialize_explain_programmatic_json(
873    issue_type: &str,
874    mode: fallow_output::RootEnvelopeMode,
875    analysis_run_id: Option<&str>,
876) -> Result<serde_json::Value, crate::ProgrammaticError> {
877    let output = explain_issue_type(issue_type)?;
878    fallow_output::serialize_explain_json_output(output, mode, analysis_run_id).map_err(|error| {
879        crate::ProgrammaticError::new(format!("JSON serialization error: {error}"), 2)
880            .with_code("json_serialization")
881    })
882}
883
884#[must_use]
885pub fn unknown_explain_error(issue_type: &str) -> crate::ProgrammaticError {
886    let message = if looks_security_explain_token(issue_type) {
887        format!(
888            "unknown issue type '{issue_type}'. Try values like tainted-sink, client-server-leak, hardcoded-secret, sql-injection, or security/sql-injection"
889        )
890    } else {
891        format!(
892            "unknown issue type '{issue_type}'. Try values like unused files, unused-export, high complexity, or code duplication"
893        )
894    };
895    crate::ProgrammaticError::new(message, 2).with_code("unknown_issue_type")
896}
897
898fn looks_security_explain_token(issue_type: &str) -> bool {
899    let normalized = issue_type.trim().to_ascii_lowercase().replace('_', "-");
900    normalized.contains("security")
901        || normalized.contains("secret")
902        || normalized.contains("sink")
903        || normalized.contains("cwe")
904        || normalized.contains("client-server")
905        || normalized.contains("injection")
906}
907
908pub const HEALTH_RULES: &[RuleDef] = &[
909    RuleDef {
910        id: "fallow/high-cyclomatic-complexity",
911        category: "Health",
912        name: "High Cyclomatic Complexity",
913        short: "Function has high cyclomatic complexity",
914        full: "McCabe cyclomatic complexity exceeds the configured threshold. Cyclomatic complexity counts the number of independent paths through a function (1 + decision points: if/else, switch cases, loops, ternary, logical operators). High values indicate functions that are hard to test exhaustively. fallow also emits this rule on synthetic `<template>` findings (Angular .html templates and inline `@Component({ template: ... })` literals), counting template control-flow blocks (`@if`, `@else if`, `@for`, `@case`, `@defer (when ...)`, legacy `*ngIf`/`*ngFor`) plus ternary and logical operators inside bound attributes and `{{ }}` interpolations; and on synthetic `<component>` rollup findings whose `cyclomatic` is the worst class method's score plus the template's. Ranking and `--targets` use the rollup total; JSON exposes the per-half breakdown under `component_rollup`.",
915        docs_path: "explanations/health#cyclomatic-complexity",
916    },
917    RuleDef {
918        id: "fallow/high-cognitive-complexity",
919        category: "Health",
920        name: "High Cognitive Complexity",
921        short: "Function has high cognitive complexity",
922        full: "SonarSource cognitive complexity exceeds the configured threshold. Unlike cyclomatic complexity, cognitive complexity penalizes nesting depth and non-linear control flow (breaks, continues, early returns). It measures how hard a function is to understand when reading sequentially. fallow also emits this rule on synthetic `<template>` findings (Angular .html templates and inline `@Component({ template: ... })` literals), where nesting penalties accumulate on stacked `@if`/`@for`/`@switch` blocks; and on synthetic `<component>` rollup findings whose `cognitive` is the worst class method's score plus the template's. Ranking and `--targets` use the rollup total; JSON exposes the per-half breakdown under `component_rollup`.",
923        docs_path: "explanations/health#cognitive-complexity",
924    },
925    RuleDef {
926        id: "fallow/high-complexity",
927        category: "Health",
928        name: "High Complexity (Both)",
929        short: "Function exceeds both complexity thresholds",
930        full: "Function exceeds both cyclomatic and cognitive complexity thresholds. This is the strongest signal that a function needs refactoring, it has many paths AND is hard to understand. The same rule fires on synthetic `<template>` findings (Angular .html templates and inline `@Component({ template: ... })` literals) when both metrics exceed their thresholds, and on synthetic `<component>` rollup findings whose totals are the worst class method's score plus the template's. Ranking and `--targets` use the rollup totals; JSON exposes the per-half breakdown under `component_rollup`.",
931        docs_path: "explanations/health#complexity-metrics",
932    },
933    RuleDef {
934        id: "fallow/high-crap-score",
935        category: "Health",
936        name: "High CRAP Score",
937        short: "Function has a high CRAP score (complexity combined with low coverage)",
938        full: "The function's CRAP (Change Risk Anti-Patterns) score meets or exceeds the configured threshold. CRAP combines cyclomatic complexity with test coverage using the Savoia and Evans (2007) formula: `CC^2 * (1 - coverage/100)^3 + CC`. High CRAP indicates changes to this function carry high risk because it is complex AND poorly tested. Pair with `--coverage` for accurate per-function scoring; without it fallow estimates coverage from the module graph.",
939        docs_path: "explanations/health#crap-score",
940    },
941    RuleDef {
942        id: "fallow/refactoring-target",
943        category: "Health",
944        name: "Refactoring Target",
945        short: "File identified as a high-priority refactoring candidate",
946        full: "File identified as a refactoring candidate based on a weighted combination of complexity density, churn velocity, dead code ratio, fan-in (blast radius), and fan-out (coupling). Categories: urgent churn+complexity, break circular dependency, split high-impact file, remove dead code, extract complex functions, reduce coupling.",
947        docs_path: "explanations/health#refactoring-targets",
948    },
949    RuleDef {
950        id: "fallow/untested-file",
951        category: "Health",
952        name: "Untested File",
953        short: "Runtime-reachable file has no test dependency path",
954        full: "A file is reachable from runtime entry points but not from any discovered test entry point. This indicates production code that no test imports, directly or transitively, according to the static module graph.",
955        docs_path: "explanations/health#coverage-gaps",
956    },
957    RuleDef {
958        id: "fallow/untested-export",
959        category: "Health",
960        name: "Untested Export",
961        short: "Runtime-reachable export has no test dependency path",
962        full: "A value export is reachable from runtime entry points but no test-reachable module references it. This is a static test dependency gap rather than line coverage, and highlights exports exercised only through production entry paths.",
963        docs_path: "explanations/health#coverage-gaps",
964    },
965    RuleDef {
966        id: "fallow/runtime-safe-to-delete",
967        category: "Health",
968        name: "Production Safe To Delete",
969        short: "Statically unused AND never invoked in production with V8 tracking",
970        full: "The function is both statically unreachable in the module graph and was never invoked during the observed runtime coverage window. This is the highest-confidence delete signal fallow emits.",
971        docs_path: "explanations/health#runtime-coverage",
972    },
973    RuleDef {
974        id: "fallow/runtime-review-required",
975        category: "Health",
976        name: "Production Review Required",
977        short: "Statically used but never invoked in production",
978        full: "The function is reachable in the module graph (or exercised by tests / untracked call sites) but was not invoked during the observed runtime coverage window. Needs a human look: may be seasonal, error-path only, or legitimately unused.",
979        docs_path: "explanations/health#runtime-coverage",
980    },
981    RuleDef {
982        id: "fallow/runtime-low-traffic",
983        category: "Health",
984        name: "Production Low Traffic",
985        short: "Function was invoked below the low-traffic threshold",
986        full: "The function was invoked in production but below the configured `--low-traffic-threshold` fraction of total trace count (spec default 0.1%). Effectively dead for the current period.",
987        docs_path: "explanations/health#runtime-coverage",
988    },
989    RuleDef {
990        id: "fallow/runtime-coverage-unavailable",
991        category: "Health",
992        name: "Runtime Coverage Unavailable",
993        short: "Runtime coverage could not be resolved for this function",
994        full: "The function could not be matched to a V8-tracked coverage entry. Common causes: the function lives in a worker thread (separate V8 isolate), it is lazy-parsed and never reached the JIT tier, or its source map did not resolve to the expected source path. This is advisory, not a dead-code signal.",
995        docs_path: "explanations/health#runtime-coverage",
996    },
997    RuleDef {
998        id: "fallow/runtime-coverage",
999        category: "Health",
1000        name: "Runtime Coverage",
1001        short: "Runtime coverage finding",
1002        full: "Generic runtime-coverage finding for verdicts not covered by a more specific rule. Covers the forward-compat `unknown` sentinel; the CLI filters `active` entries out of `runtime_coverage.findings` so the surfaced list stays actionable.",
1003        docs_path: "explanations/health#runtime-coverage",
1004    },
1005    RuleDef {
1006        id: "fallow/coverage-intelligence-risky-change",
1007        category: "Health",
1008        name: "Coverage Intelligence Risky Change",
1009        short: "Changed hot path combines high CRAP and low test coverage",
1010        full: "Coverage intelligence combined change scope, runtime hot-path evidence, low test coverage, and high CRAP into a risky-change finding. Add focused tests or split the change before merging.",
1011        docs_path: "explanations/health#coverage-intelligence",
1012    },
1013    RuleDef {
1014        id: "fallow/coverage-intelligence-delete",
1015        category: "Health",
1016        name: "Coverage Intelligence Delete",
1017        short: "Static and runtime evidence indicate code can be deleted",
1018        full: "Coverage intelligence combined static unused status, runtime cold evidence, and lack of test reachability into a high-confidence delete recommendation.",
1019        docs_path: "explanations/health#coverage-intelligence",
1020    },
1021    RuleDef {
1022        id: "fallow/coverage-intelligence-review",
1023        category: "Health",
1024        name: "Coverage Intelligence Review",
1025        short: "Cold reachable uncovered code needs owner review",
1026        full: "Coverage intelligence found code that is statically reachable but cold in runtime evidence, uncovered by tests, and ownership-risky. Route it to an owner before changing or deleting it.",
1027        docs_path: "explanations/health#coverage-intelligence",
1028    },
1029    RuleDef {
1030        id: "fallow/coverage-intelligence-refactor",
1031        category: "Health",
1032        name: "Coverage Intelligence Refactor",
1033        short: "Hot covered code has high CRAP and should be refactored carefully",
1034        full: "Coverage intelligence found hot production code that is covered by tests but still has high CRAP. Refactor carefully while preserving behavior.",
1035        docs_path: "explanations/health#coverage-intelligence",
1036    },
1037];
1038
1039pub const DUPES_RULES: &[RuleDef] = &[RuleDef {
1040    id: "fallow/code-duplication",
1041    category: "Duplication",
1042    name: "Code Duplication",
1043    short: "Duplicated code block",
1044    full: "A block of code that appears in multiple locations with identical or near-identical token sequences. Clone detection uses normalized token comparison: identifier names and literals are abstracted away in non-strict modes.",
1045    docs_path: "explanations/duplication#clone-groups",
1046}];
1047
1048pub const FLAGS_RULES: &[RuleDef] = &[RuleDef {
1049    id: "fallow/feature-flag",
1050    category: "Flags",
1051    name: "Feature Flags",
1052    short: "Detected feature flag pattern",
1053    full: "A feature flag pattern detected by `fallow flags`: environment-variable checks, flag SDK calls (LaunchDarkly, Unleash, and similar), or config-object lookups. Long-lived flags accumulate dead branches; review old flags for retirement and pair with dead-code analysis to find branches that can no longer execute.",
1054    docs_path: "cli/flags",
1055}];
1056
1057macro_rules! security_catalogue_rule {
1058    ($id:literal, $name:literal, $cwe:literal) => {
1059        RuleDef {
1060            id: concat!("security/", $id),
1061            category: "Security",
1062            name: $name,
1063            short: concat!("Catalogue security candidate for CWE-", $cwe),
1064            full: concat!(
1065                $name,
1066                " is a data-driven `fallow security` tainted-sink catalogue category with CWE-",
1067                $cwe,
1068                " metadata. fallow reports it as an unverified candidate when a captured sink shape matches this category. Use it to understand or filter `security/",
1069                $id,
1070                "` findings, then inspect the trace, source, sink, sanitization, and application context before treating it as exploitable."
1071            ),
1072            docs_path: "cli/security",
1073        }
1074    };
1075}
1076
1077pub const SECURITY_RULES: &[RuleDef] = &[
1078    RuleDef {
1079        id: "security/tainted-sink",
1080        category: "Security",
1081        name: "Tainted Sink Candidates",
1082        short: "Syntactic security sink candidates require verification",
1083        full: "The `tainted-sink` family covers data-driven `fallow security` catalogue categories. These findings are unverified candidates, not confirmed vulnerabilities. fallow can connect known source signals to captured sink shapes and add CWE metadata, but it does not prove attacker control, missing sanitization, exploitability, or business impact.",
1084        docs_path: "cli/security",
1085    },
1086    RuleDef {
1087        id: "security/client-server-leak",
1088        category: "Security",
1089        name: "Client-server Secret Leak Candidates",
1090        short: "Client-bound code reaches a non-public env read",
1091        full: "`client-server-leak` reports a candidate when a `use client` module can transitively reach a static non-public `process.env` or `import.meta.env` read. Public-by-convention env prefixes are treated as public. The finding is advisory and still needs bundle, framework, and runtime verification before treating it as a real exposure.",
1092        docs_path: "cli/security",
1093    },
1094    RuleDef {
1095        id: "security/hardcoded-secret",
1096        category: "Security",
1097        name: "Hardcoded Secret Candidates",
1098        short: "Provider-prefixed or contextual secret literals require verification",
1099        full: "`hardcoded-secret` reports opt-in candidates for provider-prefixed or contextual secret-shaped literals. The category is include-required and only runs when listed in `security.categories.include`. It avoids raw entropy alone, but every result still requires review, secret rotation decisions, and context before acting.",
1100        docs_path: "cli/security",
1101    },
1102    security_catalogue_rule!("dangerous-html", "Dangerous HTML sink", "79"),
1103    security_catalogue_rule!(
1104        "template-escape-bypass",
1105        "Template escape bypass sink",
1106        "79"
1107    ),
1108    security_catalogue_rule!("command-injection", "OS command injection sink", "78"),
1109    security_catalogue_rule!("code-injection", "Code injection sink", "94"),
1110    security_catalogue_rule!("dynamic-regex", "Dynamic regular expression sink", "1333"),
1111    security_catalogue_rule!("redos-regex", "ReDoS regex sink", "1333"),
1112    security_catalogue_rule!(
1113        "resource-amplification",
1114        "Resource amplification sink",
1115        "400"
1116    ),
1117    security_catalogue_rule!("dynamic-module-load", "Dynamic module load sink", "95"),
1118    security_catalogue_rule!("sql-injection", "SQL injection sink", "89"),
1119    security_catalogue_rule!("ssrf", "Server-side request forgery sink", "918"),
1120    security_catalogue_rule!(
1121        "secret-to-network",
1122        "Secret reaches a network request",
1123        "201"
1124    ),
1125    security_catalogue_rule!("path-traversal", "Path traversal sink", "22"),
1126    security_catalogue_rule!(
1127        "header-injection",
1128        "HTTP response header injection sink",
1129        "113"
1130    ),
1131    security_catalogue_rule!("open-redirect", "Open redirect sink", "601"),
1132    security_catalogue_rule!(
1133        "postmessage-wildcard-origin",
1134        "Wildcard postMessage target origin",
1135        "346"
1136    ),
1137    security_catalogue_rule!("tls-validation-disabled", "TLS validation disabled", "295"),
1138    security_catalogue_rule!("cleartext-transport", "Cleartext transport URL", "319"),
1139    security_catalogue_rule!(
1140        "electron-unsafe-webpreferences",
1141        "Unsafe Electron BrowserWindow preferences",
1142        "1188"
1143    ),
1144    security_catalogue_rule!(
1145        "world-writable-permission",
1146        "World-writable chmod mode",
1147        "732"
1148    ),
1149    security_catalogue_rule!(
1150        "insecure-temp-file",
1151        "Predictable temporary file path",
1152        "377"
1153    ),
1154    security_catalogue_rule!(
1155        "mysql-multiple-statements",
1156        "MySQL multiple statements enabled",
1157        "89"
1158    ),
1159    security_catalogue_rule!("permissive-cors", "Permissive CORS policy", "942"),
1160    security_catalogue_rule!("insecure-cookie", "Insecure cookie options", "614"),
1161    security_catalogue_rule!("mass-assignment", "Mass assignment sink", "915"),
1162    security_catalogue_rule!("weak-crypto", "Runtime-selectable crypto algorithm", "327"),
1163    security_catalogue_rule!("insecure-randomness", "Insecure randomness sink", "338"),
1164    security_catalogue_rule!("jwt-alg-none", "JWT alg none", "347"),
1165    security_catalogue_rule!(
1166        "jwt-verify-missing-algorithms",
1167        "JWT verify missing algorithms allowlist",
1168        "347"
1169    ),
1170    security_catalogue_rule!("deprecated-cipher", "Deprecated cipher constructor", "327"),
1171    security_catalogue_rule!(
1172        "unsafe-buffer-alloc",
1173        "Unsafe Buffer allocation sink",
1174        "1188"
1175    ),
1176    security_catalogue_rule!(
1177        "unsafe-deserialization",
1178        "Unsafe deserialization sink",
1179        "502"
1180    ),
1181    security_catalogue_rule!(
1182        "angular-trusted-html",
1183        "Angular bypassSecurityTrust sink",
1184        "79"
1185    ),
1186    security_catalogue_rule!("nextjs-open-redirect", "Next.js open redirect sink", "601"),
1187    security_catalogue_rule!("dom-document-write", "DOM document.write sink", "79"),
1188    security_catalogue_rule!("jquery-html", "jQuery .html() sink", "79"),
1189    security_catalogue_rule!(
1190        "route-send-file",
1191        "Route file-send path traversal sink",
1192        "22"
1193    ),
1194    security_catalogue_rule!("webview-injection", "WebView injected-script sink", "94"),
1195    security_catalogue_rule!("prototype-pollution", "Prototype pollution sink", "1321"),
1196    security_catalogue_rule!("zip-slip", "Archive path-traversal (zip-slip) sink", "22"),
1197    security_catalogue_rule!("nosql-injection", "NoSQL injection sink", "943"),
1198    security_catalogue_rule!("ssti", "Server-side template injection sink", "1336"),
1199    security_catalogue_rule!("xxe", "XML external entity (XXE) sink", "611"),
1200    security_catalogue_rule!("secret-pii-log", "Secret or PII logged", "532"),
1201    security_catalogue_rule!("xpath-injection", "XPath injection sink", "643"),
1202    security_catalogue_rule!(
1203        "llm-call-injection",
1204        "Untrusted input reaches an LLM call",
1205        "1427"
1206    ),
1207];
1208
1209/// Build the `_meta` object for `fallow security --format json --explain`.
1210#[must_use]
1211pub fn security_meta() -> fallow_types::envelope::Meta {
1212    fallow_output::security_meta(SECURITY_RULES.iter().map(|rule| {
1213        fallow_output::SecurityRuleMeta {
1214            id: rule.id,
1215            name: rule.name,
1216            description: rule.full,
1217            docs_path: rule.docs_path,
1218        }
1219    }))
1220}
1221
1222/// Build the `_meta` object for `fallow coverage setup --json --explain`.
1223#[must_use]
1224pub fn coverage_setup_meta() -> Value {
1225    fallow_output::coverage_setup_meta()
1226}
1227
1228/// Build the `_meta` object for `fallow coverage analyze --format json --explain`.
1229#[must_use]
1230pub fn coverage_analyze_meta() -> Value {
1231    fallow_output::coverage_analyze_meta()
1232}
1233
1234#[cfg(test)]
1235#[allow(
1236    clippy::unwrap_used,
1237    reason = "registry tests intentionally index fixture JSON"
1238)]
1239mod tests {
1240    use super::*;
1241    use serde_json::json;
1242
1243    fn meta_value(meta: fallow_types::envelope::Meta) -> Value {
1244        serde_json::to_value(meta).expect("metadata should serialize")
1245    }
1246
1247    fn check_meta() -> Value {
1248        meta_value(fallow_output::check_meta())
1249    }
1250
1251    fn health_meta() -> Value {
1252        meta_value(fallow_output::health_meta())
1253    }
1254
1255    fn dupes_meta() -> Value {
1256        meta_value(fallow_output::dupes_meta())
1257    }
1258
1259    #[test]
1260    fn rule_by_id_finds_check_rule() {
1261        let rule = rule_by_id("fallow/unused-file").unwrap();
1262        assert_eq!(rule.name, "Unused Files");
1263    }
1264
1265    #[test]
1266    fn rule_by_id_finds_health_rule() {
1267        let rule = rule_by_id("fallow/high-cyclomatic-complexity").unwrap();
1268        assert_eq!(rule.name, "High Cyclomatic Complexity");
1269    }
1270
1271    #[test]
1272    fn rule_by_id_finds_dupes_rule() {
1273        let rule = rule_by_id("fallow/code-duplication").unwrap();
1274        assert_eq!(rule.name, "Code Duplication");
1275    }
1276
1277    #[test]
1278    fn rule_by_id_finds_security_rule() {
1279        let rule = rule_by_id("security/tainted-sink").unwrap();
1280        assert_eq!(rule.name, "Tainted Sink Candidates");
1281    }
1282
1283    #[test]
1284    fn rule_by_id_returns_none_for_unknown() {
1285        assert!(rule_by_id("fallow/nonexistent").is_none());
1286        assert!(rule_by_id("").is_none());
1287    }
1288
1289    #[test]
1290    fn rule_docs_url_format() {
1291        let rule = rule_by_id("fallow/unused-export").unwrap();
1292        let url = rule_docs_url(rule);
1293        assert!(url.starts_with("https://docs.fallow.tools/"));
1294        assert!(url.contains("unused-exports"));
1295    }
1296
1297    #[test]
1298    fn result_sarif_rule_ids_have_explain_metadata() {
1299        for contract in fallow_output::issue_output_contracts() {
1300            for rule_id in contract.sarif_rule_ids {
1301                assert!(
1302                    rule_by_id(&rule_id).is_some(),
1303                    "result metadata code {} has SARIF rule id {rule_id} without RuleDef",
1304                    contract.code
1305                );
1306            }
1307        }
1308    }
1309
1310    #[test]
1311    fn check_rules_all_have_fallow_prefix() {
1312        for rule in CHECK_RULES {
1313            assert!(
1314                rule.id.starts_with("fallow/"),
1315                "rule {} should start with fallow/",
1316                rule.id
1317            );
1318        }
1319    }
1320
1321    #[test]
1322    fn check_rules_all_have_docs_path() {
1323        for rule in CHECK_RULES {
1324            assert!(
1325                !rule.docs_path.is_empty(),
1326                "rule {} should have a docs_path",
1327                rule.id
1328            );
1329        }
1330    }
1331
1332    #[test]
1333    fn check_rules_no_duplicate_ids() {
1334        let mut seen = rustc_hash::FxHashSet::default();
1335        for rule in CHECK_RULES
1336            .iter()
1337            .chain(HEALTH_RULES)
1338            .chain(DUPES_RULES)
1339            .chain(FLAGS_RULES)
1340            .chain(SECURITY_RULES)
1341        {
1342            assert!(seen.insert(rule.id), "duplicate rule id: {}", rule.id);
1343        }
1344    }
1345
1346    #[test]
1347    fn check_meta_has_docs_and_rules() {
1348        let meta = check_meta();
1349        assert!(meta.get("docs").is_some());
1350        assert!(meta.get("rules").is_some());
1351        let rules = meta["rules"].as_object().unwrap();
1352        assert_eq!(rules.len(), CHECK_RULES.len());
1353        assert!(rules.contains_key("unused-file"));
1354        assert!(rules.contains_key("unused-export"));
1355        assert!(rules.contains_key("unused-type"));
1356        assert!(rules.contains_key("unused-dependency"));
1357        assert!(rules.contains_key("unused-dev-dependency"));
1358        assert!(rules.contains_key("unused-optional-dependency"));
1359        assert!(rules.contains_key("unused-enum-member"));
1360        assert!(rules.contains_key("unused-class-member"));
1361        assert!(rules.contains_key("unresolved-import"));
1362        assert!(rules.contains_key("unlisted-dependency"));
1363        assert!(rules.contains_key("duplicate-export"));
1364        assert!(rules.contains_key("type-only-dependency"));
1365        assert!(rules.contains_key("circular-dependency"));
1366    }
1367
1368    #[test]
1369    fn check_meta_documents_per_finding_auto_fixable() {
1370        let meta = check_meta();
1371        let defs = meta["field_definitions"].as_object().unwrap();
1372        let note = defs["actions[].auto_fixable"].as_str().unwrap();
1373        assert!(
1374            note.contains("PER FINDING"),
1375            "auto_fixable note must call out per-finding evaluation"
1376        );
1377        assert!(
1378            note.contains("remove-catalog-entry"),
1379            "auto_fixable note must cite remove-catalog-entry per-instance flip"
1380        );
1381        assert!(
1382            note.contains("used_in_workspaces"),
1383            "auto_fixable note must cite the dependency-action per-instance flip"
1384        );
1385        assert!(
1386            note.contains("ignoreExports"),
1387            "auto_fixable note must cite the duplicate-exports config-fixable flip"
1388        );
1389        assert!(defs.contains_key("actions[]"));
1390    }
1391
1392    #[test]
1393    fn health_and_dupes_meta_share_actions_field_definitions() {
1394        for meta in [health_meta(), dupes_meta()] {
1395            let defs = meta["field_definitions"].as_object().unwrap();
1396            assert_eq!(
1397                defs["actions[]"].as_str().unwrap(),
1398                fallow_output::ACTIONS_FIELD_DEFINITION,
1399            );
1400            assert_eq!(
1401                defs["actions[].auto_fixable"].as_str().unwrap(),
1402                fallow_output::ACTIONS_AUTO_FIXABLE_FIELD_DEFINITION,
1403            );
1404        }
1405    }
1406
1407    #[test]
1408    fn check_meta_rule_has_required_fields() {
1409        let meta = check_meta();
1410        let rules = meta["rules"].as_object().unwrap();
1411        for (key, value) in rules {
1412            assert!(value.get("name").is_some(), "rule {key} missing 'name'");
1413            assert!(
1414                value.get("description").is_some(),
1415                "rule {key} missing 'description'"
1416            );
1417            assert!(value.get("docs").is_some(), "rule {key} missing 'docs'");
1418        }
1419    }
1420
1421    #[test]
1422    fn health_meta_has_metrics() {
1423        let meta = health_meta();
1424        assert!(meta.get("docs").is_some());
1425        let metrics = meta["metrics"].as_object().unwrap();
1426        assert!(metrics.contains_key("cyclomatic"));
1427        assert!(metrics.contains_key("cognitive"));
1428        assert!(metrics.contains_key("maintainability_index"));
1429        assert!(metrics.contains_key("complexity_density"));
1430        assert!(metrics.contains_key("fan_in"));
1431        assert!(metrics.contains_key("fan_out"));
1432    }
1433
1434    #[test]
1435    fn dupes_meta_has_metrics() {
1436        let meta = dupes_meta();
1437        assert!(meta.get("docs").is_some());
1438        let metrics = meta["metrics"].as_object().unwrap();
1439        assert!(metrics.contains_key("duplication_percentage"));
1440        assert!(metrics.contains_key("token_count"));
1441        assert!(metrics.contains_key("clone_groups"));
1442        assert!(metrics.contains_key("clone_families"));
1443    }
1444
1445    #[test]
1446    fn coverage_setup_meta_has_docs_fields_enums_and_warnings() {
1447        let meta = coverage_setup_meta();
1448        assert_eq!(meta["docs_url"], fallow_output::COVERAGE_SETUP_DOCS);
1449        assert!(
1450            meta["field_definitions"]
1451                .as_object()
1452                .unwrap()
1453                .contains_key("members[]")
1454        );
1455        assert!(
1456            meta["field_definitions"]
1457                .as_object()
1458                .unwrap()
1459                .contains_key("config_written")
1460        );
1461        assert!(
1462            meta["field_definitions"]
1463                .as_object()
1464                .unwrap()
1465                .contains_key("members[].package_manager")
1466        );
1467        assert!(
1468            meta["field_definitions"]
1469                .as_object()
1470                .unwrap()
1471                .contains_key("members[].warnings")
1472        );
1473        assert!(
1474            meta["enums"]
1475                .as_object()
1476                .unwrap()
1477                .contains_key("framework_detected")
1478        );
1479        assert!(
1480            meta["warnings"]
1481                .as_object()
1482                .unwrap()
1483                .contains_key("No runtime workspace members were detected")
1484        );
1485        assert!(
1486            meta["warnings"]
1487                .as_object()
1488                .unwrap()
1489                .contains_key("Package manager was not detected")
1490        );
1491    }
1492
1493    #[test]
1494    fn coverage_analyze_meta_documents_data_source_and_action_vocabulary() {
1495        let meta = coverage_analyze_meta();
1496        assert_eq!(meta["docs_url"], fallow_output::COVERAGE_ANALYZE_DOCS);
1497        let fields = meta["field_definitions"].as_object().unwrap();
1498        assert!(fields.contains_key("runtime_coverage.summary.data_source"));
1499        assert!(fields.contains_key("runtime_coverage.summary.last_received_at"));
1500        assert!(fields.contains_key("runtime_coverage.findings[].evidence.test_coverage"));
1501        assert!(fields.contains_key("runtime_coverage.findings[].actions[].type"));
1502        let enums = meta["enums"].as_object().unwrap();
1503        assert_eq!(enums["data_source"], json!(["local", "cloud"]));
1504        assert_eq!(enums["test_coverage"], json!(["covered", "not_covered"]));
1505        assert_eq!(enums["v8_tracking"], json!(["tracked", "untracked"]));
1506        assert_eq!(
1507            enums["action_type"],
1508            json!(["delete-cold-code", "review-runtime"])
1509        );
1510        let warnings = meta["warnings"].as_object().unwrap();
1511        assert!(warnings.contains_key("cloud_functions_unmatched"));
1512    }
1513
1514    #[test]
1515    fn health_rules_all_have_fallow_prefix() {
1516        for rule in HEALTH_RULES {
1517            assert!(
1518                rule.id.starts_with("fallow/"),
1519                "health rule {} should start with fallow/",
1520                rule.id
1521            );
1522        }
1523    }
1524
1525    #[test]
1526    fn health_rules_all_have_docs_path() {
1527        for rule in HEALTH_RULES {
1528            assert!(
1529                !rule.docs_path.is_empty(),
1530                "health rule {} should have a docs_path",
1531                rule.id
1532            );
1533        }
1534    }
1535
1536    #[test]
1537    fn health_rules_all_have_non_empty_fields() {
1538        for rule in HEALTH_RULES {
1539            assert!(
1540                !rule.name.is_empty(),
1541                "health rule {} missing name",
1542                rule.id
1543            );
1544            assert!(
1545                !rule.short.is_empty(),
1546                "health rule {} missing short description",
1547                rule.id
1548            );
1549            assert!(
1550                !rule.full.is_empty(),
1551                "health rule {} missing full description",
1552                rule.id
1553            );
1554        }
1555    }
1556
1557    #[test]
1558    fn dupes_rules_all_have_fallow_prefix() {
1559        for rule in DUPES_RULES {
1560            assert!(
1561                rule.id.starts_with("fallow/"),
1562                "dupes rule {} should start with fallow/",
1563                rule.id
1564            );
1565        }
1566    }
1567
1568    #[test]
1569    fn dupes_rules_all_have_docs_path() {
1570        for rule in DUPES_RULES {
1571            assert!(
1572                !rule.docs_path.is_empty(),
1573                "dupes rule {} should have a docs_path",
1574                rule.id
1575            );
1576        }
1577    }
1578
1579    #[test]
1580    fn dupes_rules_all_have_non_empty_fields() {
1581        for rule in DUPES_RULES {
1582            assert!(!rule.name.is_empty(), "dupes rule {} missing name", rule.id);
1583            assert!(
1584                !rule.short.is_empty(),
1585                "dupes rule {} missing short description",
1586                rule.id
1587            );
1588            assert!(
1589                !rule.full.is_empty(),
1590                "dupes rule {} missing full description",
1591                rule.id
1592            );
1593        }
1594    }
1595
1596    #[test]
1597    fn security_rules_all_have_security_prefix() {
1598        for rule in SECURITY_RULES {
1599            assert!(
1600                rule.id.starts_with("security/"),
1601                "security rule {} should start with security/",
1602                rule.id
1603            );
1604        }
1605    }
1606
1607    #[test]
1608    fn security_rules_all_have_docs_path() {
1609        for rule in SECURITY_RULES {
1610            assert_eq!(
1611                rule.docs_path, "cli/security",
1612                "security rule {} should point at security docs",
1613                rule.id
1614            );
1615        }
1616    }
1617
1618    #[test]
1619    fn security_rules_all_have_non_empty_fields() {
1620        for rule in SECURITY_RULES {
1621            assert!(
1622                !rule.name.is_empty(),
1623                "security rule {} missing name",
1624                rule.id
1625            );
1626            assert!(
1627                !rule.short.is_empty(),
1628                "security rule {} missing short description",
1629                rule.id
1630            );
1631            assert!(
1632                !rule.full.is_empty(),
1633                "security rule {} missing full description",
1634                rule.id
1635            );
1636        }
1637    }
1638
1639    #[test]
1640    fn check_rules_all_have_non_empty_fields() {
1641        for rule in CHECK_RULES {
1642            assert!(!rule.name.is_empty(), "check rule {} missing name", rule.id);
1643            assert!(
1644                !rule.short.is_empty(),
1645                "check rule {} missing short description",
1646                rule.id
1647            );
1648            assert!(
1649                !rule.full.is_empty(),
1650                "check rule {} missing full description",
1651                rule.id
1652            );
1653        }
1654    }
1655
1656    #[test]
1657    fn rule_docs_url_health_rule() {
1658        let rule = rule_by_id("fallow/high-cyclomatic-complexity").unwrap();
1659        let url = rule_docs_url(rule);
1660        assert!(url.starts_with("https://docs.fallow.tools/"));
1661        assert!(url.contains("health"));
1662    }
1663
1664    #[test]
1665    fn rule_docs_url_dupes_rule() {
1666        let rule = rule_by_id("fallow/code-duplication").unwrap();
1667        let url = rule_docs_url(rule);
1668        assert!(url.starts_with("https://docs.fallow.tools/"));
1669        assert!(url.contains("duplication"));
1670    }
1671
1672    #[test]
1673    fn rule_docs_url_security_rule() {
1674        let rule = rule_by_id("security/sql-injection").unwrap();
1675        let url = rule_docs_url(rule);
1676        assert_eq!(url, "https://docs.fallow.tools/cli/security");
1677    }
1678
1679    #[test]
1680    fn health_meta_all_metrics_have_name_and_description() {
1681        let meta = health_meta();
1682        let metrics = meta["metrics"].as_object().unwrap();
1683        for (key, value) in metrics {
1684            assert!(
1685                value.get("name").is_some(),
1686                "health metric {key} missing 'name'"
1687            );
1688            assert!(
1689                value.get("description").is_some(),
1690                "health metric {key} missing 'description'"
1691            );
1692            assert!(
1693                value.get("interpretation").is_some(),
1694                "health metric {key} missing 'interpretation'"
1695            );
1696        }
1697    }
1698
1699    #[test]
1700    fn health_meta_has_all_expected_metrics() {
1701        let meta = health_meta();
1702        let metrics = meta["metrics"].as_object().unwrap();
1703        let expected = [
1704            "cyclomatic",
1705            "cognitive",
1706            "line_count",
1707            "lines",
1708            "maintainability_index",
1709            "complexity_density",
1710            "dead_code_ratio",
1711            "fan_in",
1712            "fan_out",
1713            "score",
1714            "weighted_commits",
1715            "trend",
1716            "priority",
1717            "efficiency",
1718            "effort",
1719            "confidence",
1720            "bus_factor",
1721            "contributor_count",
1722            "share",
1723            "stale_days",
1724            "drift",
1725            "unowned",
1726            "runtime_coverage_verdict",
1727            "runtime_coverage_state",
1728            "runtime_coverage_confidence",
1729            "production_invocations",
1730            "percent_dead_in_production",
1731        ];
1732        for key in &expected {
1733            assert!(
1734                metrics.contains_key(*key),
1735                "health_meta missing expected metric: {key}"
1736            );
1737        }
1738    }
1739
1740    #[test]
1741    fn dupes_meta_all_metrics_have_name_and_description() {
1742        let meta = dupes_meta();
1743        let metrics = meta["metrics"].as_object().unwrap();
1744        for (key, value) in metrics {
1745            assert!(
1746                value.get("name").is_some(),
1747                "dupes metric {key} missing 'name'"
1748            );
1749            assert!(
1750                value.get("description").is_some(),
1751                "dupes metric {key} missing 'description'"
1752            );
1753        }
1754    }
1755
1756    #[test]
1757    fn dupes_meta_has_line_count() {
1758        let meta = dupes_meta();
1759        let metrics = meta["metrics"].as_object().unwrap();
1760        assert!(metrics.contains_key("line_count"));
1761    }
1762
1763    #[test]
1764    fn check_docs_url_valid() {
1765        assert!(fallow_output::CHECK_DOCS.starts_with("https://"));
1766        assert!(fallow_output::CHECK_DOCS.contains("dead-code"));
1767    }
1768
1769    #[test]
1770    fn health_docs_url_valid() {
1771        assert!(fallow_output::HEALTH_DOCS.starts_with("https://"));
1772        assert!(fallow_output::HEALTH_DOCS.contains("health"));
1773    }
1774
1775    #[test]
1776    fn dupes_docs_url_valid() {
1777        assert!(fallow_output::DUPES_DOCS.starts_with("https://"));
1778        assert!(fallow_output::DUPES_DOCS.contains("dupes"));
1779    }
1780
1781    #[test]
1782    fn check_meta_docs_url_matches_constant() {
1783        let meta = check_meta();
1784        assert_eq!(meta["docs"].as_str().unwrap(), fallow_output::CHECK_DOCS);
1785    }
1786
1787    #[test]
1788    fn health_meta_docs_url_matches_constant() {
1789        let meta = health_meta();
1790        assert_eq!(meta["docs"].as_str().unwrap(), fallow_output::HEALTH_DOCS);
1791    }
1792
1793    #[test]
1794    fn dupes_meta_docs_url_matches_constant() {
1795        let meta = dupes_meta();
1796        assert_eq!(meta["docs"].as_str().unwrap(), fallow_output::DUPES_DOCS);
1797    }
1798
1799    #[test]
1800    fn rule_by_id_finds_all_check_rules() {
1801        for rule in CHECK_RULES {
1802            assert!(
1803                rule_by_id(rule.id).is_some(),
1804                "rule_by_id should find check rule {}",
1805                rule.id
1806            );
1807        }
1808    }
1809
1810    #[test]
1811    fn rule_by_id_finds_all_health_rules() {
1812        for rule in HEALTH_RULES {
1813            assert!(
1814                rule_by_id(rule.id).is_some(),
1815                "rule_by_id should find health rule {}",
1816                rule.id
1817            );
1818        }
1819    }
1820
1821    #[test]
1822    fn rule_by_id_finds_all_dupes_rules() {
1823        for rule in DUPES_RULES {
1824            assert!(
1825                rule_by_id(rule.id).is_some(),
1826                "rule_by_id should find dupes rule {}",
1827                rule.id
1828            );
1829        }
1830    }
1831
1832    #[test]
1833    fn rule_by_id_finds_all_security_rules() {
1834        for rule in SECURITY_RULES {
1835            assert!(
1836                rule_by_id(rule.id).is_some(),
1837                "rule_by_id should find security rule {}",
1838                rule.id
1839            );
1840        }
1841    }
1842
1843    #[test]
1844    fn check_rules_count() {
1845        assert_eq!(CHECK_RULES.len(), 45);
1846    }
1847
1848    #[test]
1849    fn health_rules_count() {
1850        assert_eq!(HEALTH_RULES.len(), 16);
1851    }
1852
1853    #[test]
1854    fn dupes_rules_count() {
1855        assert_eq!(DUPES_RULES.len(), 1);
1856    }
1857
1858    #[test]
1859    fn flags_rules_count() {
1860        assert_eq!(FLAGS_RULES.len(), 1);
1861    }
1862
1863    #[test]
1864    fn security_rules_count() {
1865        assert_eq!(
1866            SECURITY_RULES.len(),
1867            matcher_entries_from_security_catalogue().len() + 3
1868        );
1869    }
1870
1871    #[test]
1872    fn security_rules_cover_every_catalogue_matcher() {
1873        let mut rule_ids = rustc_hash::FxHashSet::default();
1874        for rule in SECURITY_RULES {
1875            rule_ids.insert(rule.id);
1876        }
1877
1878        for matcher in matcher_entries_from_security_catalogue() {
1879            let rule_id = format!("security/{}", matcher.id);
1880            assert!(
1881                rule_ids.contains(rule_id.as_str()),
1882                "security matcher {} has no explain rule",
1883                matcher.id
1884            );
1885        }
1886    }
1887
1888    #[test]
1889    fn security_catalogue_rules_match_catalogue_title_and_cwe() {
1890        for matcher in matcher_entries_from_security_catalogue() {
1891            let rule_id = format!("security/{}", matcher.id);
1892            let rule = rule_by_id(&rule_id)
1893                .unwrap_or_else(|| panic!("security matcher {} has no explain rule", matcher.id));
1894            let cwe = format!("CWE-{}", matcher.cwe);
1895            assert_eq!(
1896                rule.name, matcher.title,
1897                "security matcher {} has stale explain title",
1898                matcher.id
1899            );
1900            assert!(
1901                rule.short.contains(&cwe),
1902                "security matcher {} explain summary does not mention {cwe}",
1903                matcher.id
1904            );
1905            assert!(
1906                rule.full.contains(&cwe),
1907                "security matcher {} explain rationale does not mention {cwe}",
1908                matcher.id
1909            );
1910        }
1911    }
1912
1913    /// Every registered rule must declare a category. The PR/MR sticky
1914    /// renderer reads this via `category_for_rule`; without an entry the
1915    /// rule silently falls into the "Dead code" default and reviewers may
1916    /// see it grouped under an unexpected section. Catching this here is
1917    /// the same pattern as `check_rules_count` for the rule count itself.
1918    #[test]
1919    fn every_rule_declares_a_category() {
1920        let allowed = [
1921            "Dead code",
1922            "Dependencies",
1923            "Duplication",
1924            "Health",
1925            "Architecture",
1926            "Suppressions",
1927            "Security",
1928            "Policy",
1929            "Flags",
1930        ];
1931        for rule in CHECK_RULES
1932            .iter()
1933            .chain(HEALTH_RULES)
1934            .chain(DUPES_RULES)
1935            .chain(FLAGS_RULES)
1936            .chain(SECURITY_RULES)
1937        {
1938            assert!(
1939                !rule.category.is_empty(),
1940                "rule {} has empty category",
1941                rule.id
1942            );
1943            assert!(
1944                allowed.contains(&rule.category),
1945                "rule {} has unrecognised category {:?}; add to allowlist or pick from {:?}",
1946                rule.id,
1947                rule.category,
1948                allowed
1949            );
1950        }
1951    }
1952
1953    #[derive(Debug)]
1954    struct MatcherEntry {
1955        id: &'static str,
1956        title: &'static str,
1957        cwe: &'static str,
1958    }
1959
1960    fn matcher_entries_from_security_catalogue() -> Vec<MatcherEntry> {
1961        let toml = include_str!("../../core/data/security_matchers.toml");
1962        let mut entries = Vec::new();
1963        let mut in_matcher = false;
1964        let mut id = None;
1965        let mut title = None;
1966        let mut cwe = None;
1967
1968        for line in toml.lines() {
1969            let trimmed = line.trim();
1970            if trimmed == "[[matcher]]" {
1971                if let (Some(id), Some(title), Some(cwe)) = (id.take(), title.take(), cwe.take()) {
1972                    entries.push(MatcherEntry { id, title, cwe });
1973                }
1974                in_matcher = true;
1975                continue;
1976            }
1977            if trimmed.starts_with("[[") {
1978                if let (Some(id), Some(title), Some(cwe)) = (id.take(), title.take(), cwe.take()) {
1979                    entries.push(MatcherEntry { id, title, cwe });
1980                }
1981                in_matcher = false;
1982                continue;
1983            }
1984            if !in_matcher {
1985                continue;
1986            }
1987            if let Some(value) = trimmed
1988                .strip_prefix("id = \"")
1989                .and_then(|value| value.strip_suffix('"'))
1990            {
1991                id = Some(value);
1992            } else if let Some(value) = trimmed
1993                .strip_prefix("title = \"")
1994                .and_then(|value| value.strip_suffix('"'))
1995            {
1996                title = Some(value);
1997            } else if let Some(value) = trimmed.strip_prefix("cwe = ") {
1998                cwe = Some(value);
1999            }
2000        }
2001
2002        if let (Some(id), Some(title), Some(cwe)) = (id.take(), title.take(), cwe.take()) {
2003            entries.push(MatcherEntry { id, title, cwe });
2004        }
2005
2006        let mut seen = rustc_hash::FxHashSet::default();
2007        entries
2008            .into_iter()
2009            .filter(|entry| seen.insert(entry.id))
2010            .collect()
2011    }
2012}