BartWaardenburg · Oct 17, 2026 · Oct 17, 2026
@@ -37,7 +37,7 @@ Fallow reports these core issue types:
 | **Test-only dependencies** | Production dependencies that only test files import (move them to devDependencies) |
 | **Stale suppressions** | `fallow-ignore` comments or `@expected-unused` JSDoc tags that no longer match any issue |
 
-Fallow also has framework-specific rules, such as unused component props and route collisions, and opt-in rules, such as private type leaks. To set the severity of a rule, see [Rules & severity](/configuration/rules). To see the filter flag of each issue type, run `fallow dead-code --help`. For circular dependencies, boundary violations, and the other architecture findings, use [`fallow architecture`](/cli/architecture).
+Fallow also has framework-specific rules, such as unused component props and route collisions, rules for [Effect](https://effect.website) projects, such as [unused Effect layers](/explanations/dead-code#unused-effect-layers), and opt-in rules, such as private type leaks. To set the severity of a rule, see [Rules & severity](/configuration/rules). To see the filter flag of each issue type, run `fallow dead-code --help`. For circular dependencies, boundary violations, and the other architecture findings, use [`fallow architecture`](/cli/architecture).
 
 Typical output with more than one issue type:
 
@@ -172,7 +172,7 @@ Fallow reports candidates only when it knows at least one reachable caller and c
     {
       "kind": "dead-code",
       "schema_version": 10,
-      "version": "3.33.1",
+      "version": "3.34.0",
       "elapsed_ms": 160,
       "total_issues": 401,
       "unused_files": [
@@ -220,7 +220,7 @@ Fallow reports candidates only when it knows at least one reachable caller and c
       "$schema": "https://json.schemastore.org/sarif-2.1.0.json",
       "version": "2.1.0",
       "runs": [{
-        "tool": { "driver": { "name": "fallow", "version": "3.33.1" } },
+        "tool": { "driver": { "name": "fallow", "version": "3.34.0" } },
         "results": [
           {
             "ruleId": "fallow/unused-export",

@@ -554,7 +554,7 @@ added-suppression:src/index.ts:2:@ts-ignore,severity=warn
 {
   "kind": "audit",
   "schema_version": 13,
-  "version": "3.33.1",
+  "version": "3.34.0",
   "command": "audit",
   "verdict": "fail",
   "changed_files_count": 12,

@@ -54,6 +54,9 @@ fallow check      # Hidden alias for fallow dead-code
 | `--unused-svelte-events` | Report only unused Svelte dispatched events |
 | `--unused-server-actions` | Report only unused server actions |
 | `--unused-load-data-keys` | Report only unused SvelteKit `load()` data keys |
+| `--unused-effect-layers` | Report only [unused Effect layers](/explanations/dead-code#unused-effect-layers): layers that only unused layers compose |
+| `--unused-tagged-errors` | Report only [unused tagged errors](/explanations/dead-code#unused-tagged-errors): Effect tagged errors that no code produces |
+| `--unproduced-catch-tags` | Report only [unproduced catch tags](/explanations/dead-code#unproduced-catch-tags): `catchTag` handlers for a tag that no code produces |
 | `--unresolved-imports` | Report only unresolved imports |
 | `--unlisted-deps` | Report only unlisted dependencies |
 | `--duplicate-exports` | Report only duplicate exports |

@@ -184,7 +184,7 @@ When the change has no structural decision, the output is `Decisions: none (no c
 {
   "kind": "decision-surface",
   "schema_version": 1,
-  "version": "3.33.1",
+  "version": "3.34.0",
   "command": "decision-surface",
   "decisions": [
     {

@@ -101,7 +101,7 @@ The last line gives the status: `ready`, `ready with warnings`, or `not ready`.
 {
   "kind": "doctor",
   "schema_version": 2,
-  "version": "3.33.1",
+  "version": "3.34.0",
   "root": ".",
   "status": "warn",
   "summary": {

@@ -425,7 +425,7 @@ fallow flags --production
 {
   "kind": "feature-flags",
   "schema_version": 8,
-  "version": "3.33.1",
+  "version": "3.34.0",
   "elapsed_ms": 116,
   "feature_flags": [],
   "total_flags": 0

@@ -485,7 +485,7 @@ Snapshots let you track the health of your codebase across builds, sprints, or r
 ```json title="snapshot.json"
 {
   "snapshot_schema_version": 12,
-  "version": "3.33.1",
+  "version": "3.34.0",
   "timestamp": "2026-03-25T14:30:00Z",
   "git_sha": "a1b2c3d",
   "git_branch": "main",
@@ -818,7 +818,7 @@ Fallow writes every entry with or without `--quiet`, so a CI job that drops stde
 ```json title="$ fallow health --format json --top 2"
 {
   "schema_version": 12,
-  "version": "3.33.1",
+  "version": "3.34.0",
   "elapsed_ms": 140,
   "summary": {
     "files_analyzed": 252,
@@ -911,7 +911,7 @@ With `--file-scores`, the JSON output has more fields:
 ```json title="$ fallow health --file-scores --format json --top 2"
 {
   "schema_version": 12,
-  "version": "3.33.1",
+  "version": "3.34.0",
   "elapsed_ms": 320,
   "summary": {
     "files_analyzed": 252,
@@ -970,7 +970,7 @@ With `--hotspots`, the JSON output has a `hotspots` array and a `hotspot_summary
 ```json title="$ fallow health --hotspots --format json --top 2"
 {
   "schema_version": 12,
-  "version": "3.33.1",
+  "version": "3.34.0",
   "elapsed_ms": 480,
   "summary": {
     "files_analyzed": 252,
@@ -1035,7 +1035,7 @@ With `--targets`, the JSON output has a `targets` array:
 ```json title="$ fallow health --targets --format json --top 2"
 {
   "schema_version": 12,
-  "version": "3.33.1",
+  "version": "3.34.0",
   "elapsed_ms": 520,
   "summary": {
     "files_analyzed": 252,
@@ -1305,7 +1305,7 @@ coverage-gaps = "warn"
 ```json title="$ fallow health --coverage-gaps --format json"
 {
   "schema_version": 12,
-  "version": "3.33.1",
+  "version": "3.34.0",
   "elapsed_ms": 280,
   "coverage_gaps": {
     "summary": {
@@ -1384,7 +1384,7 @@ Runtime coverage shows which code production actually runs. With `--runtime-cove
 ```json title="$ fallow health --runtime-coverage ./coverage --format json"
 {
   "schema_version": 12,
-  "version": "3.33.1",
+  "version": "3.34.0",
   "elapsed_ms": 412,
   "runtime_coverage": {
     "verdict": "hot-path-touched",
@@ -1500,7 +1500,7 @@ fallow health --format sarif
   "$schema": "https://json.schemastore.org/sarif-2.1.0.json",
   "version": "2.1.0",
   "runs": [{
-    "tool": { "driver": { "name": "fallow", "version": "3.33.1" } },
+    "tool": { "driver": { "name": "fallow", "version": "3.34.0" } },
     "results": [
       {
         "ruleId": "fallow/high-cyclomatic-complexity",

@@ -282,7 +282,7 @@ The editor diagnostics and [`fallow viz`](/cli/viz) show the same result. The ba
 {
   "kind": "security",
   "schema_version": 8,
-  "version": "3.33.1",
+  "version": "3.34.0",
   "elapsed_ms": 42,
   "config": {
     "rules": {

@@ -21,10 +21,12 @@ Start with all rules as `warn`. Promote one type at a time to `error` when you h
 
 When you do not configure a rule, it uses its default severity. The **Default** column in [Available rule names](#available-rule-names) shows the default of each rule. The defaults by group:
 
-- Default `off` (opt-in): `private-type-leaks`, `deprecated-exports-in-use`, `absent-component-props`, `prop-drilling`, `thin-wrapper`, `duplicate-prop-shape`, `coverage-gaps`, `feature-flags`, `require-suppression-reason`, `security-client-server-leak`, and `security-sink`.
+- Default `off` (opt-in): `private-type-leaks`, `deprecated-exports-in-use`, `absent-component-props`, `prop-drilling`, `thin-wrapper`, `duplicate-prop-shape`, `coverage-gaps`, `feature-flags`, `require-suppression-reason`, `security-client-server-leak`, `security-sink`, `diverged-clone-sibling`, and `added-dependency`.
 - Default `warn`:
   - Dependency hygiene: `unused-dev-dependencies`, `unused-optional-dependencies`, `type-only-dependencies`, `test-only-dependencies`, and `dev-dependencies-in-production`.
   - Framework components: `unused-store-members`, `unprovided-injects`, `unrendered-components`, `unused-component-props`, `unused-component-emits`, `unused-component-inputs`, `unused-component-outputs`, `unused-svelte-events`, `unused-server-actions`, and `unused-load-data-keys`.
+  - Effect: `unused-effect-layers`, `unused-tagged-errors`, and `unproduced-catch-tags`.
+  - Audit diff risk: `weakened-tests`, `added-suppression`, and `test-only-branch`.
   - Client and server directives: `invalid-client-export`, `mixed-client-server-barrel`, and `misplaced-directive`.
   - Styling: `css-token-drift`, `css-duplicate-block`, `css-selector-complexity`, `css-dead-surface`, and `css-broken-reference`.
   - pnpm cleanup: `unused-catalog-entries`, `empty-catalog-groups`, and `unused-dependency-overrides`.
@@ -115,6 +117,9 @@ stale-suppressions = "warn"
 | `unused-svelte-events` | `warn` | A Svelte `createEventDispatcher` event that no code in the project listens to |
 | `unused-server-actions` | `warn` | A Next.js Server Action, exported from a `"use server"` file, that no code references |
 | `unused-load-data-keys` | `warn` | A key of a SvelteKit `load()` return object that no consumer reads |
+| `unused-effect-layers` | `warn` | An Effect layer that only unused layers compose. Runs only when `effect` is a dependency. Fallow also accepts `unused-effect-layer`. See [Unused Effect layers](/explanations/dead-code#unused-effect-layers) |
+| `unused-tagged-errors` | `warn` | A `Data.TaggedError` or `Schema.TaggedError` class that no code constructs, fails with, or decodes. Runs only when `effect` is a dependency. See [Unused tagged errors](/explanations/dead-code#unused-tagged-errors) |
+| `unproduced-catch-tags` | `warn` | A `catchTag` handler for a project tag that no code produces. Runs only when `effect` is a dependency. See [Unproduced catch tags](/explanations/dead-code#unproduced-catch-tags) |
 | `prop-drilling` | `off` | A React or Preact prop that passes unchanged through 3 or more components to a distant consumer |
 | `thin-wrapper` | `off` | A React or Preact component whose whole body renders one child with spread props (a candidate for inlining) |
 | `duplicate-prop-shape` | `off` | Three or more React or Preact components, in two or more files, that declare the same set of prop names (a missing shared `Props` type) |
@@ -213,7 +218,11 @@ With the default rules, a `moderate` complexity finding is an `::error` annotati
 
 Each dead-code and complexity finding in the JSON output has the optional `effective_severity` field. `fallow report --from` reads it, so a saved report gives the same levels as the direct run. A saved report from an older version has no `effective_severity`. For such a report, `report --from` uses the earlier levels.
 
-`prop-drilling`, `thin-wrapper`, and `duplicate-prop-shape` findings never fail the run. Their SARIF level is `warning` at most, also when the rule is `error`. The `human`, `json`, `sarif`, `compact`, and `markdown` reports list these findings, and the editor shows them as hints. The pull request formats (`codeclimate`, `github-annotations`, `github-summary`, and the comment and review formats) do not list them.
+`prop-drilling` defaults to `off`. Set it to `error` to fail CI for a finding, or `warn` to keep it advisory even with `--fail-on-issues`. Error findings use the configured error level in CI formats. The editor still shows prop drilling as a hint. Saved JSON reports preserve their effective severity when rendered with `fallow report --from`.
+
+Earlier versions treated `prop-drilling: "error"` as advisory. If you used that setting for non-gating reports, change it to `warn` when upgrading. This affects future analysis runs. An archived JSON report with `effective_severity: "error"` renders as an error even after you change the current config to `warn`.
+
+`thin-wrapper` and `duplicate-prop-shape` findings stay advisory, also when their rules are `error`. Their SARIF level is `warning` at most. The `human`, `json`, `sarif`, `compact`, and `markdown` reports list these findings, and the editor shows them as hints. The pull request formats (`codeclimate`, `github-annotations`, `github-summary`, and the comment and review formats) do not list them.
 
 <Accordion title="Incremental adoption strategy">
 In an existing codebase, adopt fallow in steps:

@@ -750,7 +750,11 @@ A React or Preact prop that two or more intermediate components pass on without
 |:---------|:--------|
 | Off (opt-in) | Yes |
 
-This rule is off by default. To enable it, set `prop-drilling: "warn"` (or `"error"`) under `rules`. Fallow then reports one chain per drilled prop. The chain shows the source component that owns the value, each pass-through hop, and the component that uses the prop, each with file, line, and component name. To stay false-positive-safe, fallow skips the whole chain when it cannot prove a clean pass-through: any `{...props}` or `{...rest}` spread, a `cloneElement` call, a component passed as a prop, render prop, or function-as-children, a matching context `*.Provider` in the subtree (where drilling can be a deliberate choice), or any dynamic or unresolvable hop. The rule runs only when `react`, `react-dom`, `next`, or `preact` is a declared dependency. When you enable it, it also adds a small, capped penalty to the health score: one point per chain, with a cap of five. With the rule off, the health score does not change.
+This rule is off by default. Set `prop-drilling: "warn"` under `rules` for advisory findings, or `"error"` to fail CI when fallow finds a chain. A `warn` finding stays advisory even with `--fail-on-issues`. Fallow then reports one chain per drilled prop. The chain shows the source component that owns the value, each pass-through hop, and the component that uses the prop, each with file, line, and component name. To stay false-positive-safe, fallow skips the whole chain when it cannot prove a clean pass-through: any `{...props}` or `{...rest}` spread, a `cloneElement` call, a component passed as a prop, render prop, or function-as-children, a matching context `*.Provider` in the subtree (where drilling can be a deliberate choice), or any dynamic or unresolvable hop. The rule runs only when `react`, `react-dom`, `next`, or `preact` is a declared dependency. When you enable it, it also adds a small, capped penalty to the health score: one point per chain, with a cap of five. With the rule off, the health score does not change.
+
+You can save existing chains with `--save-baseline` and gate later runs with `--baseline`. Fallow identifies a chain by its source path, component, and prop. A change to the route or depth of the same source chain stays inherited. `fallow audit --gate new-only` gates new source identities; use `--gate all` to include inherited findings.
+
+Changed-file and changed-line scopes retain an enforced (`error`) chain when any downstream hop changes, while the reported location stays at the source. Changed-file scopes retain an advisory (`warn`) chain only when its source file changes. In the editor, both levels remain hints.
 
 **When to act:** Move the component that uses the prop next to the data, move the value to a React context or provider at a hop in the middle of the chain, or compose the components so that the intermediate components no longer pass the prop. There is no auto-fix, because the right refactor is a design choice. To suppress one chain, use `// fallow-ignore-next-line prop-drilling`, or set the rule to `off`.
 

@@ -50,7 +50,7 @@ When you enable telemetry, fallow records one small, high-level event per analys
 {
   "schema_version": 2,
   "event": "workflow_completed",
-  "fallow_version": "3.33.1",
+  "fallow_version": "3.34.0",
   "workflow": "audit",
   "integration_surface": "mcp",
   "invocation_context": "agent",

@@ -129,7 +129,7 @@ When you enable the rule, it reports one chain for each drilled prop. The chain
 Off by default.
 
 <Note>
-To enable it, set `prop-drilling: "warn"` (or `"error"`) under `rules`. The enabled rule also adds a small penalty to the health score: one point for each chain, with a maximum of five. When the rule is off, the health score does not change.
+Set `prop-drilling: "warn"` under `rules` for advisory findings, or `"error"` to make findings fail CI. A `warn` finding stays advisory even with `--fail-on-issues`. The enabled rule also adds a small penalty to the health score: one point for each chain, with a maximum of five. When the rule is off, the health score does not change.
 </Note>
 
 See [prop drilling](/explanations/dead-code#prop-drilling).

@@ -111,7 +111,7 @@ export FALLOW_GATE_MIN_VERSION=3.0.0
 export FALLOW_GATE_MIN_VERSION=
 ```
 
-Each block logs the path and version of the binary that ran, for example `fallow-gate: blocked by fallow 3.33.1 at /usr/local/bin/fallow`. You can see which binary ran without more debugging. The header of the installed script also has `# Installer version: X.Y.Z`. Use it when the gate does not agree with your current `fallow --version`.
+Each block logs the path and version of the binary that ran, for example `fallow-gate: blocked by fallow 3.34.0 at /usr/local/bin/fallow`. You can see which binary ran without more debugging. The header of the installed script also has `# Installer version: X.Y.Z`. Use it when the gate does not agree with your current `fallow --version`.
 
 ## Inspect hook state
 

@@ -249,7 +249,7 @@ When the response `capabilities` array has `function_identity_v2`, cloud runtime
 {
   "kind": "dead-code",
   "schema_version": 10,
-  "version": "3.33.1",
+  "version": "3.34.0",
   "elapsed_ms": 42,
   "total_issues": 1,
   "unused_exports": [

@@ -86,7 +86,10 @@ The `fallow migrate` command translates your knip configuration to a fallow conf
 | `ignoreDependencies` | `ignoreDependencies` (a regex becomes a glob when a glob matches the same packages, see [Warnings and caveats](#warnings-and-caveats)) |
 | `ignoreExportsUsedInFile` | `ignoreExportsUsedInFile` (boolean and `{ type, interface }` object form both supported) |
 | `rules`, `include`, `exclude` | `rules` (knip issue types map to fallow rule names) |
-| `ignoreBinaries` | -- (not applicable) |
+| `ignoreBinaries`, `ignoreGlobalBinaries` | -- (not applicable) |
+| `cycles` | -- (no allow-list for exact cycle paths. The warning suggests `circularDependencies.ignoreLazyImports` or a `// fallow-ignore-next-line circular-dependency` comment) |
+| `preprocessor`, `preprocessorOptions` | -- (not supported. The warning suggests to post-process the `fallow --format json` output) |
+| `compilers`, `asyncCompilers` | -- (fallow parses with Oxc and has no custom compilers) |
 | Plugin configs | -- (fallow's built-in plugins detect the framework; the migration warns you to remove the section) |
 
 ## Warnings and caveats