From 1c1c2010fb433b26dc978faeb140cd53faa05887 Mon Sep 17 00:00:00 2001
From: Erik Axel Nielsen <erikaxel@lucalabs.com>
Date: Thu, 3 Sep 2026 13:55:09 +0200
Subject: [PATCH 1/8] Report the errors swallowed while computing a cache
 digest

Every rescue in the digest machinery returns a neutral value, so a
misconfiguration, an autoload failure, or a raising `inherited` hook
degrades to "no component dependencies" and the application serves
stale HTML with nothing reported anywhere.

- Route the four swallow sites through CacheDigest.handle_error
- Log at `warn` through ActiveSupport's logger, preserving the production
  guarantee that a stale fragment beats a failed render
- Raise instead in local environments, configurable with
  config.view_component.raise_on_cache_digest_errors
---
 docs/CHANGELOG.md                             |   4 +
 docs/api.md                                   |  13 ++
 docs/guide/caching.md                         |  16 +++
 lib/view_component/cache_digest.rb            |  33 ++++-
 .../cache_digest/dependency_tracking.rb       |   8 +-
 lib/view_component/cache_digest/resolver.rb   |   9 +-
 lib/view_component/config.rb                  |  21 +++-
 lib/view_component/engine.rb                  |   1 +
 test/sandbox/test/config_test.rb              |   1 +
 .../test/experimentally_cacheable_test.rb     | 113 ++++++++++++++++--
 10 files changed, 193 insertions(+), 26 deletions(-)

diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 9834fc583..7e57c5e9c 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -10,6 +10,10 @@ nav_order: 6
 
 ## main
 
+* Report the errors swallowed while computing a component's cache digest, instead of degrading to an untracked component with no indication that anything went wrong. Digest errors are now raised in local environments and logged at `warn` elsewhere, configurable with `config.view_component.raise_on_cache_digest_errors`.
+
+    *Erik Axel Nielsen*
+
 ## 4.15.0
 
 * Add experimental caching support, opt-in per component via `include ViewComponent::ExperimentallyCacheable`.
diff --git a/docs/api.md b/docs/api.md
index b615b2d54..859b75cf1 100644
--- a/docs/api.md
+++ b/docs/api.md
@@ -294,6 +294,19 @@ A custom default layout used for the previews index page and individual previews
 
     config.view_component.previews.default_layout = "preview_layout"
 
+### `.raise_on_cache_digest_errors`
+
+Whether to raise when computing a component's cache digest fails.
+
+Digest failures are otherwise swallowed, since a stale fragment is
+preferable to a failed render, and reported to the log at `warn`. That
+trade is wrong in development and test, where an untracked component
+looks exactly like a component that was never cached.
+
+Defaults to `true` in local environments and `false` elsewhere:
+
+    config.view_component.raise_on_cache_digest_errors = false
+
 ## ViewComponent::TestHelpers
 
 ### `#render_in_view_context(...)`
diff --git a/docs/guide/caching.md b/docs/guide/caching.md
index 183de010d..cc46681f1 100644
--- a/docs/guide/caching.md
+++ b/docs/guide/caching.md
@@ -189,6 +189,22 @@ The same works in a template, where the branch is often the more natural place f
 
 Declared components must include `ViewComponent::ExperimentallyCacheable` themselves, since a component that hasn't opted in has no digest to depend on.
 
+## When a digest can't be computed
+
+Computing a digest touches the autoloader, the filesystem, and Action View's dependency trackers, any of which can fail. In production those failures are swallowed: a component that can't be digested is left untracked, which is exactly the behavior it had before opting in, and a stale fragment beats a failed render.
+
+That trade is wrong while developing, where an untracked component is indistinguishable from a component that was never cached in the first place. Digest failures are therefore raised in local environments and logged at `warn` everywhere else:
+
+```console
+[ViewComponent] Ignored an error while resolving PostComponent: NoMethodError: ...
+```
+
+To swallow them locally too, or to raise them in production:
+
+```ruby
+config.view_component.raise_on_cache_digest_errors = false
+```
+
 ## Caveats
 
 **Self-caching components can't take content from their callers.** Besides a block, this covers `with_content` and slots set by the caller:
diff --git a/lib/view_component/cache_digest.rb b/lib/view_component/cache_digest.rb
index 98694c8dc..cb58eaf0c 100644
--- a/lib/view_component/cache_digest.rb
+++ b/lib/view_component/cache_digest.rb
@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require "active_support/dependencies/autoload"
+require "active_support/log_subscriber"
 require "action_view/digestor"
 require "action_view/render_parser"
 
@@ -146,8 +147,8 @@ def partial_paths_in(source, name)
         RENDER_PARSER.new(name, source).render_calls.uniq.select do |path|
           source.include?(path) || source.include?(path.sub(%r{(\A|/)_}, '\1'))
         end
-      rescue
-        # Never let digest computation break rendering.
+      rescue => error
+        handle_error(error, "scanning #{name} for rendered partials")
         []
       end
 
@@ -221,6 +222,30 @@ def install!
         end
       end
 
+      # Report an exception the digest machinery swallowed.
+      #
+      # Every rescue here degrades to "this component has no dependencies",
+      # which is indistinguishable from a component that was never cached: the
+      # digest stops changing and the application serves stale HTML. A
+      # misconfiguration, an autoload failure, or a raising `inherited` hook is
+      # therefore completely invisible.
+      #
+      # In production a stale fragment beats a failed render, so the exception
+      # is only logged. Locally the trade goes the other way, so it's re-raised
+      # by default; see `config.view_component.raise_on_cache_digest_errors`.
+      #
+      # @private
+      def handle_error(error, context)
+        raise error if ViewComponent::Base.config.raise_on_cache_digest_errors
+
+        logger&.warn { "[ViewComponent] Ignored an error while #{context}: #{error.class}: #{error.message}" }
+      end
+
+      # @return [ActiveSupport::BroadcastLogger, Logger, nil] nil outside a Rails application.
+      def logger
+        ActiveSupport::LogSubscriber.logger
+      end
+
       private
 
       # Resolve a constant name to a component that opted into caching.
@@ -234,8 +259,8 @@ def constantize_component(constant_name)
         return unless component.respond_to?(:__vc_cacheable?) && component.__vc_cacheable?
 
         component
-      rescue
-        # Never let digest computation break rendering.
+      rescue => error
+        handle_error(error, "resolving #{constant_name}")
         nil
       end
     end
diff --git a/lib/view_component/cache_digest/dependency_tracking.rb b/lib/view_component/cache_digest/dependency_tracking.rb
index 737616dde..851efc8b2 100644
--- a/lib/view_component/cache_digest/dependency_tracking.rb
+++ b/lib/view_component/cache_digest/dependency_tracking.rb
@@ -27,10 +27,10 @@ def find_dependencies(name, template, view_paths = nil)
         end
 
         dependencies + CacheDigest.dependencies_in(template)
-      rescue
-        # A broken digest is preferable to a broken render. Falling back to the
-        # dependencies Rails found on its own means the component simply isn't
-        # tracked, which is the pre-existing behavior.
+      rescue => error
+        # Falling back to the dependencies Rails found on its own means the
+        # component simply isn't tracked, which is the pre-existing behavior.
+        CacheDigest.handle_error(error, "tracking component dependencies in #{name}")
         super
       end
 
diff --git a/lib/view_component/cache_digest/resolver.rb b/lib/view_component/cache_digest/resolver.rb
index eca6198bf..9e078aedb 100644
--- a/lib/view_component/cache_digest/resolver.rb
+++ b/lib/view_component/cache_digest/resolver.rb
@@ -30,10 +30,11 @@ def find_templates(name, prefix, partial, details, locals = [])
         return [] unless component
 
         [build_template(component, virtual_path, details)]
-      rescue
-        # Never let digest resolution break rendering. Returning no template
-        # makes the Digestor treat this as a missing node, which degrades to
-        # the behavior components have without this feature.
+      rescue => error
+        # Returning no template makes the Digestor treat this as a missing
+        # node, which degrades to the behavior components have without this
+        # feature.
+        CacheDigest.handle_error(error, "building the digest template for #{virtual_path || name}")
         []
       end
 
diff --git a/lib/view_component/config.rb b/lib/view_component/config.rb
index 0ad336838..7b6bd453b 100644
--- a/lib/view_component/config.rb
+++ b/lib/view_component/config.rb
@@ -14,7 +14,8 @@ def defaults
         ActiveSupport::OrderedOptions.new.merge!({
           generate: default_generate_options,
           previews: default_previews_options,
-          instrumentation_enabled: false
+          instrumentation_enabled: false,
+          raise_on_cache_digest_errors: default_raise_on_cache_digest_errors
         })
       end
 
@@ -131,6 +132,20 @@ def defaults
       # Whether ActiveSupport notifications are enabled.
       # Defaults to `false`.
 
+      # @!attribute raise_on_cache_digest_errors
+      #
+      # @return [Boolean]
+      # Whether to raise when computing a component's cache digest fails.
+      #
+      # Digest failures are otherwise swallowed, since a stale fragment is
+      # preferable to a failed render, and reported to the log at `warn`. That
+      # trade is wrong in development and test, where an untracked component
+      # looks exactly like a component that was never cached.
+      #
+      # Defaults to `true` in local environments and `false` elsewhere:
+      #
+      #     config.view_component.raise_on_cache_digest_errors = false
+
       def default_preview_paths
         (default_rails_preview_paths + default_rails_engines_preview_paths).uniq
       end
@@ -155,6 +170,10 @@ def registered_rails_engines_with_previews
         end
       end
 
+      def default_raise_on_cache_digest_errors
+        defined?(Rails.env) && Rails.env.local?
+      end
+
       def default_generate_options
         options = ActiveSupport::OrderedOptions.new(false)
         options.preview_path = ""
diff --git a/lib/view_component/engine.rb b/lib/view_component/engine.rb
index dc0a6e1c7..be33d4729 100644
--- a/lib/view_component/engine.rb
+++ b/lib/view_component/engine.rb
@@ -15,6 +15,7 @@ class Engine < Rails::Engine # :nodoc:
         options[config_option] ||= ViewComponent::Base.public_send(config_option)
       end
       options.instrumentation_enabled = false if options.instrumentation_enabled.nil?
+      options.raise_on_cache_digest_errors = Rails.env.local? if options.raise_on_cache_digest_errors.nil?
       options.previews.enabled = (Rails.env.development? || Rails.env.test?) if options.previews.enabled.nil?
 
       if options.previews.enabled
diff --git a/test/sandbox/test/config_test.rb b/test/sandbox/test/config_test.rb
index 9347a6ac1..d4380391e 100644
--- a/test/sandbox/test/config_test.rb
+++ b/test/sandbox/test/config_test.rb
@@ -13,6 +13,7 @@ def test_defaults_are_correct
       assert_equal @config.previews.controller, "ViewComponentsController"
       assert_equal @config.previews.route, "/rails/view_components"
       assert_equal @config.instrumentation_enabled, false
+      assert_equal @config.raise_on_cache_digest_errors, Rails.env.local?
       assert_equal @config.previews.paths, ["#{Rails.root}/test/components/previews"]
     end
 
diff --git a/test/sandbox/test/experimentally_cacheable_test.rb b/test/sandbox/test/experimentally_cacheable_test.rb
index bb0566163..4e09fae57 100644
--- a/test/sandbox/test/experimentally_cacheable_test.rb
+++ b/test/sandbox/test/experimentally_cacheable_test.rb
@@ -204,8 +204,22 @@ def test_partial_paths_are_not_extracted_from_sources_without_render
   end
 
   def test_partial_path_extraction_swallows_parser_errors
+    swallowing_digest_errors do |log|
+      ViewComponent::CacheDigest::RENDER_PARSER.stub(:new, ->(*) { raise "boom" }) do
+        assert_empty ViewComponent::CacheDigest.partial_paths_in("render \"a/b\"", "a/b")
+      end
+
+      assert_match "Ignored an error while scanning a/b for rendered partials: RuntimeError: boom", log.string
+    end
+  end
+
+  def test_partial_path_extraction_raises_parser_errors_locally
     ViewComponent::CacheDigest::RENDER_PARSER.stub(:new, ->(*) { raise "boom" }) do
-      assert_empty ViewComponent::CacheDigest.partial_paths_in("render \"a/b\"", "a/b")
+      error = assert_raises(RuntimeError) do
+        ViewComponent::CacheDigest.partial_paths_in("render \"a/b\"", "a/b")
+      end
+
+      assert_equal "boom", error.message
     end
   end
 
@@ -437,32 +451,74 @@ def test_resolver_is_identified_by_class
   def test_resolver_returns_no_template_when_synthesis_fails
     resolver = ViewComponent::CacheDigest::Resolver.instance
 
+    swallowing_digest_errors do |log|
+      ViewComponent::CacheDigest.stub(:component_for, ->(_) { raise "boom" }) do
+        assert_empty resolver.find_templates("cacheable_component", "view_component/cache_digest", true, {})
+      end
+
+      assert_match(
+        "Ignored an error while building the digest template for " \
+          "view_component/cache_digest/cacheable_component: RuntimeError: boom",
+        log.string
+      )
+    end
+  end
+
+  def test_resolver_raises_when_synthesis_fails_locally
+    resolver = ViewComponent::CacheDigest::Resolver.instance
+
     ViewComponent::CacheDigest.stub(:component_for, ->(_) { raise "boom" }) do
-      assert_empty resolver.find_templates("cacheable_component", "view_component/cache_digest", true, {})
+      assert_raises(RuntimeError) do
+        resolver.find_templates("cacheable_component", "view_component/cache_digest", true, {})
+      end
     end
   end
 
   def test_dependency_tracking_falls_back_when_scanning_fails
     template = build_template("<%= render CacheableComponent.new(title: 'a') %>")
 
+    swallowing_digest_errors do |log|
+      ViewComponent::CacheDigest.stub(:dependencies_in, ->(_) { raise "boom" }) do
+        refute_includes(
+          ActionView::DependencyTracker.find_dependencies("some/template", template, []),
+          "view_component/cache_digest/cacheable_component"
+        )
+      end
+
+      assert_match "Ignored an error while tracking component dependencies in some/template", log.string
+    end
+  end
+
+  def test_dependency_tracking_raises_when_scanning_fails_locally
+    template = build_template("<%= render CacheableComponent.new(title: 'a') %>")
+
     ViewComponent::CacheDigest.stub(:dependencies_in, ->(_) { raise "boom" }) do
-      refute_includes(
-        ActionView::DependencyTracker.find_dependencies("some/template", template, []),
-        "view_component/cache_digest/cacheable_component"
-      )
+      assert_raises(RuntimeError) { ActionView::DependencyTracker.find_dependencies("some/template", template, []) }
     end
   end
 
   def test_constantizing_swallows_unexpected_errors
-    Object.const_set(:BoomComponent, Class.new do
-      def self.__vc_cacheable?
-        raise ArgumentError
+    with_boom_component do
+      swallowing_digest_errors do |log|
+        assert_nil ViewComponent::CacheDigest.send(:constantize_component, "BoomComponent")
+
+        assert_match "Ignored an error while resolving BoomComponent: ArgumentError", log.string
       end
-    end)
+    end
+  end
 
-    assert_nil ViewComponent::CacheDigest.send(:constantize_component, "BoomComponent")
-  ensure
-    Object.send(:remove_const, :BoomComponent)
+  def test_constantizing_raises_unexpected_errors_locally
+    with_boom_component do
+      assert_raises(ArgumentError) { ViewComponent::CacheDigest.send(:constantize_component, "BoomComponent") }
+    end
+  end
+
+  def test_digest_errors_are_swallowed_without_a_logger
+    without_raising_digest_errors do
+      ViewComponent::CacheDigest.stub(:logger, nil) do
+        assert_nil ViewComponent::CacheDigest.handle_error(RuntimeError.new("boom"), "digesting")
+      end
+    end
   end
 
   def test_install_is_idempotent
@@ -487,6 +543,37 @@ def recompile(component)
     component.__vc_compile(force: true)
   end
 
+  # The digest machinery raises in local environments, and the sandbox runs as
+  # `test`, so the swallow-and-report path has to be opted into explicitly.
+  def without_raising_digest_errors
+    previous = ViewComponent::Base.config.raise_on_cache_digest_errors
+    ViewComponent::Base.config.raise_on_cache_digest_errors = false
+
+    yield
+  ensure
+    ViewComponent::Base.config.raise_on_cache_digest_errors = previous
+  end
+
+  def swallowing_digest_errors
+    log = StringIO.new
+
+    without_raising_digest_errors do
+      ViewComponent::CacheDigest.stub(:logger, ActiveSupport::Logger.new(log)) { yield log }
+    end
+  end
+
+  def with_boom_component
+    Object.const_set(:BoomComponent, Class.new do
+      def self.__vc_cacheable?
+        raise ArgumentError
+      end
+    end)
+
+    yield
+  ensure
+    Object.send(:remove_const, :BoomComponent)
+  end
+
   def build_template(source)
     ActionView::Template.new(
       source,

From 8ff09fff75ef1aea1c1b2c31c5d9fa83480a3a32 Mon Sep 17 00:00:00 2001
From: Joel Hawksley <joel@hawksley.org>
Date: Tue, 22 Sep 2026 13:40:45 -0600
Subject: [PATCH 2/8] Raise cache digest errors

Match Rails' digest behavior by allowing parser, autoload, dependency tracker, and resolver failures to propagate instead of silently leaving components untracked.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 docs/CHANGELOG.md                             |  2 +-
 docs/api.md                                   | 13 ---
 docs/guide/caching.md                         | 14 +--
 lib/view_component/cache_digest.rb            | 31 -------
 .../cache_digest/dependency_tracking.rb       |  5 --
 lib/view_component/cache_digest/resolver.rb   |  6 --
 lib/view_component/config.rb                  | 21 +----
 lib/view_component/engine.rb                  |  1 -
 test/sandbox/test/config_test.rb              |  1 -
 .../test/experimentally_cacheable_test.rb     | 86 +------------------
 10 files changed, 7 insertions(+), 173 deletions(-)

diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 605244d0b..6deaf18eb 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -10,7 +10,7 @@ nav_order: 6
 
 ## main
 
-* Report the errors swallowed while computing a component's cache digest, instead of degrading to an untracked component with no indication that anything went wrong. Digest errors are now raised in local environments and logged at `warn` elsewhere, configurable with `config.view_component.raise_on_cache_digest_errors`.
+* Raise errors encountered while computing a component's cache digest, instead of silently degrading to an untracked component that can serve stale fragments.
 
     *Erik Axel Nielsen*
 
diff --git a/docs/api.md b/docs/api.md
index 859b75cf1..b615b2d54 100644
--- a/docs/api.md
+++ b/docs/api.md
@@ -294,19 +294,6 @@ A custom default layout used for the previews index page and individual previews
 
     config.view_component.previews.default_layout = "preview_layout"
 
-### `.raise_on_cache_digest_errors`
-
-Whether to raise when computing a component's cache digest fails.
-
-Digest failures are otherwise swallowed, since a stale fragment is
-preferable to a failed render, and reported to the log at `warn`. That
-trade is wrong in development and test, where an untracked component
-looks exactly like a component that was never cached.
-
-Defaults to `true` in local environments and `false` elsewhere:
-
-    config.view_component.raise_on_cache_digest_errors = false
-
 ## ViewComponent::TestHelpers
 
 ### `#render_in_view_context(...)`
diff --git a/docs/guide/caching.md b/docs/guide/caching.md
index edcd9b5b9..eef183fd8 100644
--- a/docs/guide/caching.md
+++ b/docs/guide/caching.md
@@ -206,19 +206,7 @@ Declared components must include `ViewComponent::ExperimentallyCacheable` themse
 
 ## When a digest can't be computed
 
-Computing a digest touches the autoloader, the filesystem, and Action View's dependency trackers, any of which can fail. In production those failures are swallowed: a component that can't be digested is left untracked, which is exactly the behavior it had before opting in, and a stale fragment beats a failed render.
-
-That trade is wrong while developing, where an untracked component is indistinguishable from a component that was never cached in the first place. Digest failures are therefore raised in local environments and logged at `warn` everywhere else:
-
-```console
-[ViewComponent] Ignored an error while resolving PostComponent: NoMethodError: ...
-```
-
-To swallow them locally too, or to raise them in production:
-
-```ruby
-config.view_component.raise_on_cache_digest_errors = false
-```
+Computing a digest touches the autoloader, the filesystem, and Action View's dependency trackers, any of which can fail. ViewComponent lets those errors raise, matching Rails' digest behavior. Otherwise a component could silently become untracked and serve stale fragments.
 
 ## Caveats
 
diff --git a/lib/view_component/cache_digest.rb b/lib/view_component/cache_digest.rb
index cb58eaf0c..87fa35ed0 100644
--- a/lib/view_component/cache_digest.rb
+++ b/lib/view_component/cache_digest.rb
@@ -1,7 +1,6 @@
 # frozen_string_literal: true
 
 require "active_support/dependencies/autoload"
-require "active_support/log_subscriber"
 require "action_view/digestor"
 require "action_view/render_parser"
 
@@ -147,9 +146,6 @@ def partial_paths_in(source, name)
         RENDER_PARSER.new(name, source).render_calls.uniq.select do |path|
           source.include?(path) || source.include?(path.sub(%r{(\A|/)_}, '\1'))
         end
-      rescue => error
-        handle_error(error, "scanning #{name} for rendered partials")
-        []
       end
 
       # Action View has shipped its render parser as a class (Rails 7.1, and
@@ -222,30 +218,6 @@ def install!
         end
       end
 
-      # Report an exception the digest machinery swallowed.
-      #
-      # Every rescue here degrades to "this component has no dependencies",
-      # which is indistinguishable from a component that was never cached: the
-      # digest stops changing and the application serves stale HTML. A
-      # misconfiguration, an autoload failure, or a raising `inherited` hook is
-      # therefore completely invisible.
-      #
-      # In production a stale fragment beats a failed render, so the exception
-      # is only logged. Locally the trade goes the other way, so it's re-raised
-      # by default; see `config.view_component.raise_on_cache_digest_errors`.
-      #
-      # @private
-      def handle_error(error, context)
-        raise error if ViewComponent::Base.config.raise_on_cache_digest_errors
-
-        logger&.warn { "[ViewComponent] Ignored an error while #{context}: #{error.class}: #{error.message}" }
-      end
-
-      # @return [ActiveSupport::BroadcastLogger, Logger, nil] nil outside a Rails application.
-      def logger
-        ActiveSupport::LogSubscriber.logger
-      end
-
       private
 
       # Resolve a constant name to a component that opted into caching.
@@ -259,9 +231,6 @@ def constantize_component(constant_name)
         return unless component.respond_to?(:__vc_cacheable?) && component.__vc_cacheable?
 
         component
-      rescue => error
-        handle_error(error, "resolving #{constant_name}")
-        nil
       end
     end
 
diff --git a/lib/view_component/cache_digest/dependency_tracking.rb b/lib/view_component/cache_digest/dependency_tracking.rb
index 851efc8b2..f6100c0bb 100644
--- a/lib/view_component/cache_digest/dependency_tracking.rb
+++ b/lib/view_component/cache_digest/dependency_tracking.rb
@@ -27,11 +27,6 @@ def find_dependencies(name, template, view_paths = nil)
         end
 
         dependencies + CacheDigest.dependencies_in(template)
-      rescue => error
-        # Falling back to the dependencies Rails found on its own means the
-        # component simply isn't tracked, which is the pre-existing behavior.
-        CacheDigest.handle_error(error, "tracking component dependencies in #{name}")
-        super
       end
 
       # @private
diff --git a/lib/view_component/cache_digest/resolver.rb b/lib/view_component/cache_digest/resolver.rb
index 9e078aedb..6ad9e9dc7 100644
--- a/lib/view_component/cache_digest/resolver.rb
+++ b/lib/view_component/cache_digest/resolver.rb
@@ -30,12 +30,6 @@ def find_templates(name, prefix, partial, details, locals = [])
         return [] unless component
 
         [build_template(component, virtual_path, details)]
-      rescue => error
-        # Returning no template makes the Digestor treat this as a missing
-        # node, which degrades to the behavior components have without this
-        # feature.
-        CacheDigest.handle_error(error, "building the digest template for #{virtual_path || name}")
-        []
       end
 
       def to_s
diff --git a/lib/view_component/config.rb b/lib/view_component/config.rb
index 7b6bd453b..0ad336838 100644
--- a/lib/view_component/config.rb
+++ b/lib/view_component/config.rb
@@ -14,8 +14,7 @@ def defaults
         ActiveSupport::OrderedOptions.new.merge!({
           generate: default_generate_options,
           previews: default_previews_options,
-          instrumentation_enabled: false,
-          raise_on_cache_digest_errors: default_raise_on_cache_digest_errors
+          instrumentation_enabled: false
         })
       end
 
@@ -132,20 +131,6 @@ def defaults
       # Whether ActiveSupport notifications are enabled.
       # Defaults to `false`.
 
-      # @!attribute raise_on_cache_digest_errors
-      #
-      # @return [Boolean]
-      # Whether to raise when computing a component's cache digest fails.
-      #
-      # Digest failures are otherwise swallowed, since a stale fragment is
-      # preferable to a failed render, and reported to the log at `warn`. That
-      # trade is wrong in development and test, where an untracked component
-      # looks exactly like a component that was never cached.
-      #
-      # Defaults to `true` in local environments and `false` elsewhere:
-      #
-      #     config.view_component.raise_on_cache_digest_errors = false
-
       def default_preview_paths
         (default_rails_preview_paths + default_rails_engines_preview_paths).uniq
       end
@@ -170,10 +155,6 @@ def registered_rails_engines_with_previews
         end
       end
 
-      def default_raise_on_cache_digest_errors
-        defined?(Rails.env) && Rails.env.local?
-      end
-
       def default_generate_options
         options = ActiveSupport::OrderedOptions.new(false)
         options.preview_path = ""
diff --git a/lib/view_component/engine.rb b/lib/view_component/engine.rb
index 013bddee3..c6d31b13c 100644
--- a/lib/view_component/engine.rb
+++ b/lib/view_component/engine.rb
@@ -15,7 +15,6 @@ class Engine < Rails::Engine # :nodoc:
         options[config_option] ||= ViewComponent::Base.public_send(config_option)
       end
       options.instrumentation_enabled = false if options.instrumentation_enabled.nil?
-      options.raise_on_cache_digest_errors = Rails.env.local? if options.raise_on_cache_digest_errors.nil?
       options.previews.enabled = (Rails.env.development? || Rails.env.test?) if options.previews.enabled.nil?
 
       if options.previews.enabled
diff --git a/test/sandbox/test/config_test.rb b/test/sandbox/test/config_test.rb
index d4380391e..9347a6ac1 100644
--- a/test/sandbox/test/config_test.rb
+++ b/test/sandbox/test/config_test.rb
@@ -13,7 +13,6 @@ def test_defaults_are_correct
       assert_equal @config.previews.controller, "ViewComponentsController"
       assert_equal @config.previews.route, "/rails/view_components"
       assert_equal @config.instrumentation_enabled, false
-      assert_equal @config.raise_on_cache_digest_errors, Rails.env.local?
       assert_equal @config.previews.paths, ["#{Rails.root}/test/components/previews"]
     end
 
diff --git a/test/sandbox/test/experimentally_cacheable_test.rb b/test/sandbox/test/experimentally_cacheable_test.rb
index 8bd96bc4f..877db7952 100644
--- a/test/sandbox/test/experimentally_cacheable_test.rb
+++ b/test/sandbox/test/experimentally_cacheable_test.rb
@@ -203,17 +203,7 @@ def test_partial_paths_are_not_extracted_from_sources_without_render
     assert_empty ViewComponent::CacheDigest.partial_paths_in("def call; end", "a/b")
   end
 
-  def test_partial_path_extraction_swallows_parser_errors
-    swallowing_digest_errors do |log|
-      ViewComponent::CacheDigest::RENDER_PARSER.stub(:new, ->(*) { raise "boom" }) do
-        assert_empty ViewComponent::CacheDigest.partial_paths_in("render \"a/b\"", "a/b")
-      end
-
-      assert_match "Ignored an error while scanning a/b for rendered partials: RuntimeError: boom", log.string
-    end
-  end
-
-  def test_partial_path_extraction_raises_parser_errors_locally
+  def test_partial_path_extraction_raises_parser_errors
     ViewComponent::CacheDigest::RENDER_PARSER.stub(:new, ->(*) { raise "boom" }) do
       error = assert_raises(RuntimeError) do
         ViewComponent::CacheDigest.partial_paths_in("render \"a/b\"", "a/b")
@@ -493,23 +483,7 @@ def test_resolver_is_identified_by_class
     assert_equal resolver, ViewComponent::CacheDigest::Resolver.new
   end
 
-  def test_resolver_returns_no_template_when_synthesis_fails
-    resolver = ViewComponent::CacheDigest::Resolver.instance
-
-    swallowing_digest_errors do |log|
-      ViewComponent::CacheDigest.stub(:component_for, ->(_) { raise "boom" }) do
-        assert_empty resolver.find_templates("cacheable_component", "view_component/cache_digest", true, {})
-      end
-
-      assert_match(
-        "Ignored an error while building the digest template for " \
-          "view_component/cache_digest/cacheable_component: RuntimeError: boom",
-        log.string
-      )
-    end
-  end
-
-  def test_resolver_raises_when_synthesis_fails_locally
+  def test_resolver_raises_when_synthesis_fails
     resolver = ViewComponent::CacheDigest::Resolver.instance
 
     ViewComponent::CacheDigest.stub(:component_for, ->(_) { raise "boom" }) do
@@ -519,22 +493,7 @@ def test_resolver_raises_when_synthesis_fails_locally
     end
   end
 
-  def test_dependency_tracking_falls_back_when_scanning_fails
-    template = build_template("<%= render CacheableComponent.new(title: 'a') %>")
-
-    swallowing_digest_errors do |log|
-      ViewComponent::CacheDigest.stub(:dependencies_in, ->(_) { raise "boom" }) do
-        refute_includes(
-          ActionView::DependencyTracker.find_dependencies("some/template", template, []),
-          "view_component/cache_digest/cacheable_component"
-        )
-      end
-
-      assert_match "Ignored an error while tracking component dependencies in some/template", log.string
-    end
-  end
-
-  def test_dependency_tracking_raises_when_scanning_fails_locally
+  def test_dependency_tracking_raises_when_scanning_fails
     template = build_template("<%= render CacheableComponent.new(title: 'a') %>")
 
     ViewComponent::CacheDigest.stub(:dependencies_in, ->(_) { raise "boom" }) do
@@ -542,30 +501,12 @@ def test_dependency_tracking_raises_when_scanning_fails_locally
     end
   end
 
-  def test_constantizing_swallows_unexpected_errors
-    with_boom_component do
-      swallowing_digest_errors do |log|
-        assert_nil ViewComponent::CacheDigest.send(:constantize_component, "BoomComponent")
-
-        assert_match "Ignored an error while resolving BoomComponent: ArgumentError", log.string
-      end
-    end
-  end
-
-  def test_constantizing_raises_unexpected_errors_locally
+  def test_constantizing_raises_unexpected_errors
     with_boom_component do
       assert_raises(ArgumentError) { ViewComponent::CacheDigest.send(:constantize_component, "BoomComponent") }
     end
   end
 
-  def test_digest_errors_are_swallowed_without_a_logger
-    without_raising_digest_errors do
-      ViewComponent::CacheDigest.stub(:logger, nil) do
-        assert_nil ViewComponent::CacheDigest.handle_error(RuntimeError.new("boom"), "digesting")
-      end
-    end
-  end
-
   def test_install_is_idempotent
     resolver_count = ActionController::Base.view_paths.count { |path| path.is_a?(ViewComponent::CacheDigest::Resolver) }
 
@@ -588,25 +529,6 @@ def recompile(component)
     component.__vc_compile(force: true)
   end
 
-  # The digest machinery raises in local environments, and the sandbox runs as
-  # `test`, so the swallow-and-report path has to be opted into explicitly.
-  def without_raising_digest_errors
-    previous = ViewComponent::Base.config.raise_on_cache_digest_errors
-    ViewComponent::Base.config.raise_on_cache_digest_errors = false
-
-    yield
-  ensure
-    ViewComponent::Base.config.raise_on_cache_digest_errors = previous
-  end
-
-  def swallowing_digest_errors
-    log = StringIO.new
-
-    without_raising_digest_errors do
-      ViewComponent::CacheDigest.stub(:logger, ActiveSupport::Logger.new(log)) { yield log }
-    end
-  end
-
   def with_boom_component
     Object.const_set(:BoomComponent, Class.new do
       def self.__vc_cacheable?

From 0e6ff7efc8ddddef06ab5d15c4399a53acab6fbe Mon Sep 17 00:00:00 2001
From: Joel Hawksley <joel@hawksley.org>
Date: Tue, 22 Sep 2026 13:53:04 -0600
Subject: [PATCH 3/8] Fix cache digest prose lint

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 docs/CHANGELOG.md     | 2 +-
 docs/guide/caching.md | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 6deaf18eb..bdf1055df 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -10,7 +10,7 @@ nav_order: 6
 
 ## main
 
-* Raise errors encountered while computing a component's cache digest, instead of silently degrading to an untracked component that can serve stale fragments.
+* Raise errors encountered while computing a component's cache digest, instead of degrading to an untracked component that can serve stale fragments.
 
     *Erik Axel Nielsen*
 
diff --git a/docs/guide/caching.md b/docs/guide/caching.md
index eef183fd8..5cbcfe3f0 100644
--- a/docs/guide/caching.md
+++ b/docs/guide/caching.md
@@ -206,7 +206,7 @@ Declared components must include `ViewComponent::ExperimentallyCacheable` themse
 
 ## When a digest can't be computed
 
-Computing a digest touches the autoloader, the filesystem, and Action View's dependency trackers, any of which can fail. ViewComponent lets those errors raise, matching Rails' digest behavior. Otherwise a component could silently become untracked and serve stale fragments.
+Computing a digest touches the autoloader, the filesystem, and Action View's dependency trackers, any of which can fail. ViewComponent lets those errors raise, matching Rails' digest behavior. Otherwise a component could become untracked and serve stale fragments without warning.
 
 ## Caveats
 

From 572073b7d49f4bf16d926b75ba16e47e31eeb231 Mon Sep 17 00:00:00 2001
From: Joel Hawksley <joel@hawksley.org>
Date: Tue, 22 Sep 2026 13:57:41 -0600
Subject: [PATCH 4/8] Test digest errors through a component

Replace CacheDigest stubs and private constantization calls with a cacheable component exercised through the public cache_digest API.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 .../raising_cache_digest_component.rb         | 25 +++++++++
 .../test/experimentally_cacheable_test.rb     | 55 +++----------------
 2 files changed, 34 insertions(+), 46 deletions(-)
 create mode 100644 test/sandbox/app/components/raising_cache_digest_component.rb

diff --git a/test/sandbox/app/components/raising_cache_digest_component.rb b/test/sandbox/app/components/raising_cache_digest_component.rb
new file mode 100644
index 000000000..a5f3b106e
--- /dev/null
+++ b/test/sandbox/app/components/raising_cache_digest_component.rb
@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+class RaisingCacheDigestComponent < ViewComponent::Base
+  include ViewComponent::ExperimentallyCacheable
+
+  cache_on :identity
+
+  class_attribute :raise_on_digest, default: false
+
+  def self.sidecar_files(*)
+    raise "boom" if raise_on_digest
+
+    super
+  end
+
+  def call
+    "raising cache digest"
+  end
+
+  private
+
+  def identity
+    "raising-cache-digest"
+  end
+end
diff --git a/test/sandbox/test/experimentally_cacheable_test.rb b/test/sandbox/test/experimentally_cacheable_test.rb
index 877db7952..607f5ccce 100644
--- a/test/sandbox/test/experimentally_cacheable_test.rb
+++ b/test/sandbox/test/experimentally_cacheable_test.rb
@@ -41,6 +41,15 @@ def test_cache_digest_is_computable_outside_a_request
     refute_empty digest
   end
 
+  def test_cache_digest_errors_are_raised
+    RaisingCacheDigestComponent.raise_on_digest = true
+    error = assert_raises(RuntimeError) { RaisingCacheDigestComponent.cache_digest }
+
+    assert_equal "boom", error.message
+  ensure
+    RaisingCacheDigestComponent.raise_on_digest = false
+  end
+
   def test_cache_digest_changes_when_the_template_changes
     assert_digest_changes(
       "app/components/cacheable_component.html.erb",
@@ -203,16 +212,6 @@ def test_partial_paths_are_not_extracted_from_sources_without_render
     assert_empty ViewComponent::CacheDigest.partial_paths_in("def call; end", "a/b")
   end
 
-  def test_partial_path_extraction_raises_parser_errors
-    ViewComponent::CacheDigest::RENDER_PARSER.stub(:new, ->(*) { raise "boom" }) do
-      error = assert_raises(RuntimeError) do
-        ViewComponent::CacheDigest.partial_paths_in("render \"a/b\"", "a/b")
-      end
-
-      assert_equal "boom", error.message
-    end
-  end
-
   # Action View has shipped the parser as a class (7.1, main) and as a module
   # with a `Default` implementation (7.2 through 8.1). Exercised with doubles so
   # both shapes are covered whichever version is running.
@@ -483,30 +482,6 @@ def test_resolver_is_identified_by_class
     assert_equal resolver, ViewComponent::CacheDigest::Resolver.new
   end
 
-  def test_resolver_raises_when_synthesis_fails
-    resolver = ViewComponent::CacheDigest::Resolver.instance
-
-    ViewComponent::CacheDigest.stub(:component_for, ->(_) { raise "boom" }) do
-      assert_raises(RuntimeError) do
-        resolver.find_templates("cacheable_component", "view_component/cache_digest", true, {})
-      end
-    end
-  end
-
-  def test_dependency_tracking_raises_when_scanning_fails
-    template = build_template("<%= render CacheableComponent.new(title: 'a') %>")
-
-    ViewComponent::CacheDigest.stub(:dependencies_in, ->(_) { raise "boom" }) do
-      assert_raises(RuntimeError) { ActionView::DependencyTracker.find_dependencies("some/template", template, []) }
-    end
-  end
-
-  def test_constantizing_raises_unexpected_errors
-    with_boom_component do
-      assert_raises(ArgumentError) { ViewComponent::CacheDigest.send(:constantize_component, "BoomComponent") }
-    end
-  end
-
   def test_install_is_idempotent
     resolver_count = ActionController::Base.view_paths.count { |path| path.is_a?(ViewComponent::CacheDigest::Resolver) }
 
@@ -529,18 +504,6 @@ def recompile(component)
     component.__vc_compile(force: true)
   end
 
-  def with_boom_component
-    Object.const_set(:BoomComponent, Class.new do
-      def self.__vc_cacheable?
-        raise ArgumentError
-      end
-    end)
-
-    yield
-  ensure
-    Object.send(:remove_const, :BoomComponent)
-  end
-
   def build_template(source, virtual_path: "test/template")
     ActionView::Template.new(
       source,

From 9380c1b459ba53cd75d51206297b286e3ca590a6 Mon Sep 17 00:00:00 2001
From: Joel Hawksley <joel@hawksley.org>
Date: Tue, 22 Sep 2026 14:00:45 -0600
Subject: [PATCH 5/8] Exercise errors through cache_on

Use a real cache key method that raises during a normal cached render instead of overriding component internals.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 .../raising_cache_digest_component.rb         | 25 -------------------
 .../components/raising_cache_key_component.rb | 17 +++++++++++++
 .../test/experimentally_cacheable_test.rb     |  9 +++----
 3 files changed, 21 insertions(+), 30 deletions(-)
 delete mode 100644 test/sandbox/app/components/raising_cache_digest_component.rb
 create mode 100644 test/sandbox/app/components/raising_cache_key_component.rb

diff --git a/test/sandbox/app/components/raising_cache_digest_component.rb b/test/sandbox/app/components/raising_cache_digest_component.rb
deleted file mode 100644
index a5f3b106e..000000000
--- a/test/sandbox/app/components/raising_cache_digest_component.rb
+++ /dev/null
@@ -1,25 +0,0 @@
-# frozen_string_literal: true
-
-class RaisingCacheDigestComponent < ViewComponent::Base
-  include ViewComponent::ExperimentallyCacheable
-
-  cache_on :identity
-
-  class_attribute :raise_on_digest, default: false
-
-  def self.sidecar_files(*)
-    raise "boom" if raise_on_digest
-
-    super
-  end
-
-  def call
-    "raising cache digest"
-  end
-
-  private
-
-  def identity
-    "raising-cache-digest"
-  end
-end
diff --git a/test/sandbox/app/components/raising_cache_key_component.rb b/test/sandbox/app/components/raising_cache_key_component.rb
new file mode 100644
index 000000000..b7225803b
--- /dev/null
+++ b/test/sandbox/app/components/raising_cache_key_component.rb
@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+class RaisingCacheKeyComponent < ViewComponent::Base
+  include ViewComponent::ExperimentallyCacheable
+
+  cache_on :identity
+
+  def call
+    "raising cache key"
+  end
+
+  private
+
+  def identity
+    raise "boom"
+  end
+end
diff --git a/test/sandbox/test/experimentally_cacheable_test.rb b/test/sandbox/test/experimentally_cacheable_test.rb
index 607f5ccce..c58ecb46d 100644
--- a/test/sandbox/test/experimentally_cacheable_test.rb
+++ b/test/sandbox/test/experimentally_cacheable_test.rb
@@ -41,13 +41,12 @@ def test_cache_digest_is_computable_outside_a_request
     refute_empty digest
   end
 
-  def test_cache_digest_errors_are_raised
-    RaisingCacheDigestComponent.raise_on_digest = true
-    error = assert_raises(RuntimeError) { RaisingCacheDigestComponent.cache_digest }
+  def test_cache_on_method_errors_are_raised
+    error = with_caching do
+      assert_raises(RuntimeError) { render_inline(RaisingCacheKeyComponent.new) }
+    end
 
     assert_equal "boom", error.message
-  ensure
-    RaisingCacheDigestComponent.raise_on_digest = false
   end
 
   def test_cache_digest_changes_when_the_template_changes

From e6630597abc416e52fd97e583f7c78c1ddb81eea Mon Sep 17 00:00:00 2001
From: Joel Hawksley <joel@hawksley.org>
Date: Tue, 22 Sep 2026 14:07:23 -0600
Subject: [PATCH 6/8] Test digest errors through public API

Exercise autoload, template dependency tracking, and digest source failures through real components and cache_digest without stubbing ViewComponent internals.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 ...eable_raising_ruby_dependency_component.rb | 13 ++++++++++++
 ...ing_template_dependency_component.html.erb |  1 +
 ...e_raising_template_dependency_component.rb |  9 +++++++++
 ...able_unreadable_digest_source_component.rb |  9 +++++++++
 .../placeholder                               |  1 +
 .../components/raising_cache_key_component.rb | 17 ----------------
 .../test/experimentally_cacheable_test.rb     | 20 ++++++++++++++-----
 .../cache_digest/raising_ruby_dependency.rb   |  3 +++
 .../raising_template_dependency.rb            |  3 +++
 9 files changed, 54 insertions(+), 22 deletions(-)
 create mode 100644 test/sandbox/app/components/cacheable_raising_ruby_dependency_component.rb
 create mode 100644 test/sandbox/app/components/cacheable_raising_template_dependency_component.html.erb
 create mode 100644 test/sandbox/app/components/cacheable_raising_template_dependency_component.rb
 create mode 100644 test/sandbox/app/components/cacheable_unreadable_digest_source_component.rb
 create mode 100644 test/sandbox/app/components/cacheable_unreadable_digest_source_component.yml/placeholder
 delete mode 100644 test/sandbox/app/components/raising_cache_key_component.rb
 create mode 100644 test/sandbox/test/fixtures/cache_digest/raising_ruby_dependency.rb
 create mode 100644 test/sandbox/test/fixtures/cache_digest/raising_template_dependency.rb

diff --git a/test/sandbox/app/components/cacheable_raising_ruby_dependency_component.rb b/test/sandbox/app/components/cacheable_raising_ruby_dependency_component.rb
new file mode 100644
index 000000000..0b5299df6
--- /dev/null
+++ b/test/sandbox/app/components/cacheable_raising_ruby_dependency_component.rb
@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+module CacheDigestFixtures
+  autoload :RaisingRubyDependency, Rails.root.join("test/fixtures/cache_digest/raising_ruby_dependency.rb")
+end
+
+class CacheableRaisingRubyDependencyComponent < ViewComponent::Base
+  include ViewComponent::ExperimentallyCacheable
+
+  def call
+    render CacheDigestFixtures::RaisingRubyDependency.new
+  end
+end
diff --git a/test/sandbox/app/components/cacheable_raising_template_dependency_component.html.erb b/test/sandbox/app/components/cacheable_raising_template_dependency_component.html.erb
new file mode 100644
index 000000000..8cd72058b
--- /dev/null
+++ b/test/sandbox/app/components/cacheable_raising_template_dependency_component.html.erb
@@ -0,0 +1 @@
+<%= render CacheDigestFixtures::RaisingTemplateDependency.new %>
diff --git a/test/sandbox/app/components/cacheable_raising_template_dependency_component.rb b/test/sandbox/app/components/cacheable_raising_template_dependency_component.rb
new file mode 100644
index 000000000..20a092cfb
--- /dev/null
+++ b/test/sandbox/app/components/cacheable_raising_template_dependency_component.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+module CacheDigestFixtures
+  autoload :RaisingTemplateDependency, Rails.root.join("test/fixtures/cache_digest/raising_template_dependency.rb")
+end
+
+class CacheableRaisingTemplateDependencyComponent < ViewComponent::Base
+  include ViewComponent::ExperimentallyCacheable
+end
diff --git a/test/sandbox/app/components/cacheable_unreadable_digest_source_component.rb b/test/sandbox/app/components/cacheable_unreadable_digest_source_component.rb
new file mode 100644
index 000000000..19db7d5dd
--- /dev/null
+++ b/test/sandbox/app/components/cacheable_unreadable_digest_source_component.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class CacheableUnreadableDigestSourceComponent < ViewComponent::Base
+  include ViewComponent::ExperimentallyCacheable
+
+  def call
+    "unreadable digest source"
+  end
+end
diff --git a/test/sandbox/app/components/cacheable_unreadable_digest_source_component.yml/placeholder b/test/sandbox/app/components/cacheable_unreadable_digest_source_component.yml/placeholder
new file mode 100644
index 000000000..2e61bb449
--- /dev/null
+++ b/test/sandbox/app/components/cacheable_unreadable_digest_source_component.yml/placeholder
@@ -0,0 +1 @@
+This directory is intentionally unreadable as a digest source.
diff --git a/test/sandbox/app/components/raising_cache_key_component.rb b/test/sandbox/app/components/raising_cache_key_component.rb
deleted file mode 100644
index b7225803b..000000000
--- a/test/sandbox/app/components/raising_cache_key_component.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-# frozen_string_literal: true
-
-class RaisingCacheKeyComponent < ViewComponent::Base
-  include ViewComponent::ExperimentallyCacheable
-
-  cache_on :identity
-
-  def call
-    "raising cache key"
-  end
-
-  private
-
-  def identity
-    raise "boom"
-  end
-end
diff --git a/test/sandbox/test/experimentally_cacheable_test.rb b/test/sandbox/test/experimentally_cacheable_test.rb
index c58ecb46d..2db444fad 100644
--- a/test/sandbox/test/experimentally_cacheable_test.rb
+++ b/test/sandbox/test/experimentally_cacheable_test.rb
@@ -41,12 +41,22 @@ def test_cache_digest_is_computable_outside_a_request
     refute_empty digest
   end
 
-  def test_cache_on_method_errors_are_raised
-    error = with_caching do
-      assert_raises(RuntimeError) { render_inline(RaisingCacheKeyComponent.new) }
-    end
+  def test_cache_digest_raises_when_a_ruby_dependency_fails_to_load
+    error = assert_raises(RuntimeError) { CacheableRaisingRubyDependencyComponent.cache_digest }
+
+    assert_equal "raising Ruby dependency", error.message
+  end
+
+  def test_cache_digest_raises_when_a_template_dependency_fails_to_load
+    error = assert_raises(RuntimeError) { CacheableRaisingTemplateDependencyComponent.cache_digest }
+
+    assert_equal "raising template dependency", error.message
+  end
+
+  def test_cache_digest_raises_when_a_digest_source_cannot_be_read
+    error = assert_raises(Errno::EISDIR) { CacheableUnreadableDigestSourceComponent.cache_digest }
 
-    assert_equal "boom", error.message
+    assert_includes error.message, "cacheable_unreadable_digest_source_component.yml"
   end
 
   def test_cache_digest_changes_when_the_template_changes
diff --git a/test/sandbox/test/fixtures/cache_digest/raising_ruby_dependency.rb b/test/sandbox/test/fixtures/cache_digest/raising_ruby_dependency.rb
new file mode 100644
index 000000000..cbdc86b12
--- /dev/null
+++ b/test/sandbox/test/fixtures/cache_digest/raising_ruby_dependency.rb
@@ -0,0 +1,3 @@
+# frozen_string_literal: true
+
+raise "raising Ruby dependency"
diff --git a/test/sandbox/test/fixtures/cache_digest/raising_template_dependency.rb b/test/sandbox/test/fixtures/cache_digest/raising_template_dependency.rb
new file mode 100644
index 000000000..3a53bd73f
--- /dev/null
+++ b/test/sandbox/test/fixtures/cache_digest/raising_template_dependency.rb
@@ -0,0 +1,3 @@
+# frozen_string_literal: true
+
+raise "raising template dependency"

From f5b1d9b557ef6f846b6aa1825c4f59226fc58361 Mon Sep 17 00:00:00 2001
From: Joel Hawksley <joel@hawksley.org>
Date: Tue, 22 Sep 2026 14:09:58 -0600
Subject: [PATCH 7/8] Autoload digest fixtures with Zeitwerk

Use a dedicated Rails autoload path for failing dependency fixtures instead of inline Ruby autoload declarations.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 .../components/cacheable_raising_ruby_dependency_component.rb | 4 ----
 .../cacheable_raising_template_dependency_component.rb        | 4 ----
 test/sandbox/config/application.rb                            | 1 +
 .../raising_ruby_dependency.rb                                | 0
 .../raising_template_dependency.rb                            | 0
 5 files changed, 1 insertion(+), 8 deletions(-)
 rename test/sandbox/test/fixtures/{cache_digest => cache_digest_fixtures}/raising_ruby_dependency.rb (100%)
 rename test/sandbox/test/fixtures/{cache_digest => cache_digest_fixtures}/raising_template_dependency.rb (100%)

diff --git a/test/sandbox/app/components/cacheable_raising_ruby_dependency_component.rb b/test/sandbox/app/components/cacheable_raising_ruby_dependency_component.rb
index 0b5299df6..bf5445e59 100644
--- a/test/sandbox/app/components/cacheable_raising_ruby_dependency_component.rb
+++ b/test/sandbox/app/components/cacheable_raising_ruby_dependency_component.rb
@@ -1,9 +1,5 @@
 # frozen_string_literal: true
 
-module CacheDigestFixtures
-  autoload :RaisingRubyDependency, Rails.root.join("test/fixtures/cache_digest/raising_ruby_dependency.rb")
-end
-
 class CacheableRaisingRubyDependencyComponent < ViewComponent::Base
   include ViewComponent::ExperimentallyCacheable
 
diff --git a/test/sandbox/app/components/cacheable_raising_template_dependency_component.rb b/test/sandbox/app/components/cacheable_raising_template_dependency_component.rb
index 20a092cfb..29e3f2b08 100644
--- a/test/sandbox/app/components/cacheable_raising_template_dependency_component.rb
+++ b/test/sandbox/app/components/cacheable_raising_template_dependency_component.rb
@@ -1,9 +1,5 @@
 # frozen_string_literal: true
 
-module CacheDigestFixtures
-  autoload :RaisingTemplateDependency, Rails.root.join("test/fixtures/cache_digest/raising_template_dependency.rb")
-end
-
 class CacheableRaisingTemplateDependencyComponent < ViewComponent::Base
   include ViewComponent::ExperimentallyCacheable
 end
diff --git a/test/sandbox/config/application.rb b/test/sandbox/config/application.rb
index a8310d2c3..65c9082fd 100644
--- a/test/sandbox/config/application.rb
+++ b/test/sandbox/config/application.rb
@@ -44,6 +44,7 @@ class Application < Rails::Application
 
     # Prepare test_set_no_duplicate_autoload_paths
     config.autoload_paths.push("#{config.root}/my/components/previews")
+    config.autoload_paths.push("#{config.root}/test/fixtures")
     config.view_component.previews.paths << "#{config.root}/my/components/previews"
     config.view_component.previews.paths << "#{Rails.root}/lib/component_previews"
 
diff --git a/test/sandbox/test/fixtures/cache_digest/raising_ruby_dependency.rb b/test/sandbox/test/fixtures/cache_digest_fixtures/raising_ruby_dependency.rb
similarity index 100%
rename from test/sandbox/test/fixtures/cache_digest/raising_ruby_dependency.rb
rename to test/sandbox/test/fixtures/cache_digest_fixtures/raising_ruby_dependency.rb
diff --git a/test/sandbox/test/fixtures/cache_digest/raising_template_dependency.rb b/test/sandbox/test/fixtures/cache_digest_fixtures/raising_template_dependency.rb
similarity index 100%
rename from test/sandbox/test/fixtures/cache_digest/raising_template_dependency.rb
rename to test/sandbox/test/fixtures/cache_digest_fixtures/raising_template_dependency.rb

From 70e8601083474abce81c7bf8dfb2c50e6650dc33 Mon Sep 17 00:00:00 2001
From: Joel Hawksley <joel@hawksley.org>
Date: Tue, 22 Sep 2026 14:11:27 -0600
Subject: [PATCH 8/8] Update docs/CHANGELOG.md

---
 docs/CHANGELOG.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index bdf1055df..a6153f043 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -10,7 +10,7 @@ nav_order: 6
 
 ## main
 
-* Raise errors encountered while computing a component's cache digest, instead of degrading to an untracked component that can serve stale fragments.
+* Raise errors encountered while computing a component's cache digest instead of degrading to an untracked component that can serve stale fragments.
 
     *Erik Axel Nielsen*