diff --git a/src/dune_rules/compilation_context.ml b/src/dune_rules/compilation_context.ml
index e9bd6ae1a3e..e523354beae 100644
--- a/src/dune_rules/compilation_context.ml
+++ b/src/dune_rules/compilation_context.ml
@@ -259,6 +259,19 @@ let create
     let profile = Context.profile context in
     eval_opaque ocaml profile opaque
   in
+  let* has_library_deps =
+    (* Single-module stanzas still run ocamldep when they have library deps so
+       the per-module filter can inform the result. *)
+    let open Resolve.Memo.O in
+    let+ direct = direct_requires
+    and+ hidden = hidden_requires in
+    match direct, hidden with
+    | [], [] -> false
+    | _ -> true
+  in
+  (* Resolution errors surface later through the normal compilation rules;
+     assume deps are present here. *)
+  let has_library_deps = Resolve.peek has_library_deps |> Result.value ~default:true in
   let+ dep_graphs =
     Dep_rules.rules
       ~dir:(Obj_dir.dir obj_dir)
@@ -268,6 +281,7 @@ let create
       ~impl:implements
       ~modules
       ~for_
+      ~has_library_deps
   and+ bin_annot =
     match bin_annot with
     | Some b -> Memo.return b
diff --git a/src/dune_rules/dep_rules.ml b/src/dune_rules/dep_rules.ml
index b9e70e4768d..5dc2272211b 100644
--- a/src/dune_rules/dep_rules.ml
+++ b/src/dune_rules/dep_rules.ml
@@ -504,10 +504,14 @@ let for_module ~obj_dir ~modules ~sandbox ~impl ~dir ~sctx ~for_ module_ =
     (deps_of ~modules ~transitive_deps ~imported_vlib_deps (Normal module_))
 ;;
 
-let rules ~obj_dir ~modules ~sandbox ~impl ~sctx ~dir ~for_ =
+let rules ~obj_dir ~modules ~sandbox ~impl ~sctx ~dir ~for_ ~has_library_deps =
   match Modules.With_vlib.as_singleton modules with
-  | Some m -> Memo.return (Dep_graph.Ml_kind.dummy m)
-  | None ->
+  | Some m when (not has_library_deps) || Compilation_mode.equal for_ Melange ->
+    (* Single-module stanzas have no intra-stanza deps; the dep graph is only
+       consumed by the per-module filter in [lib_deps_for_module]. That filter
+       doesn't activate for Melange (see its [can_filter]) — skip ocamldep. *)
+    Memo.return (Dep_graph.Ml_kind.dummy m)
+  | Some _ | None ->
     let transitive_deps, imported_vlib_deps =
       make_transitive_deps ~obj_dir ~modules ~sandbox ~impl ~dir ~sctx ~for_
     in
diff --git a/src/dune_rules/dep_rules.mli b/src/dune_rules/dep_rules.mli
index 8e1324d6050..7390f136291 100644
--- a/src/dune_rules/dep_rules.mli
+++ b/src/dune_rules/dep_rules.mli
@@ -13,6 +13,9 @@ val for_module
   -> Module.t
   -> Module.t list Action_builder.t Ml_kind.Dict.t Memo.t
 
+(** Single-module stanzas short-circuit ocamldep when [not has_library_deps] or
+    [for_ = Melange]: the per-module filter that consumes the dep graph doesn't
+    activate in those cases. *)
 val rules
   :  obj_dir:Path.Build.t Obj_dir.t
   -> modules:Modules.With_vlib.t
@@ -21,6 +24,7 @@ val rules
   -> sctx:Super_context.t
   -> dir:Path.Build.t
   -> for_:Compilation_mode.t
+  -> has_library_deps:bool
   -> Dep_graph.Ml_kind.t Memo.t
 
 val read_immediate_deps_of
diff --git a/src/dune_rules/module_compilation.ml b/src/dune_rules/module_compilation.ml
index d2c1556bc58..557416cd92a 100644
--- a/src/dune_rules/module_compilation.ml
+++ b/src/dune_rules/module_compilation.ml
@@ -8,27 +8,179 @@ let all_libs cctx =
   d @ h
 ;;
 
-(* Returns the include flags and lib-file deps for compiling [m]. The scaffold
-   form is glob-only: include flags come from the cctx's [Includes] (-I/-H over
-   the full lib list) and deps come from [deps_of_entries] over the same list.
-   The per-module tight filter activates in a follow-up; arguments unused by
-   this form are reserved for that filter. *)
-let lib_deps_for_module
-      ~cctx
-      ~obj_dir:_
-      ~for_:_
-      ~dep_graph:_
-      ~opaque
-      ~cm_kind
-      ~ml_kind:(_ : Ml_kind.t)
-      ~mode:(_ : Lib_mode.t)
-      _m
-  =
+let union_module_name_sets_mapped xs ~f =
+  Action_builder.List.map xs ~f
+  |> Action_builder.map
+       ~f:(List.fold_left ~init:Module_name.Set.empty ~f:Module_name.Set.union)
+;;
+
+let module_kind_is_filterable m =
+  match Module.kind m with
+  | Root | Wrapped_compat | Impl_vmodule | Virtual | Parameter -> false
+  | Intf_only | Impl | Alias _ -> true
+;;
+
+(* BFS over tight-eligible entries: each (lib, entry) pair's impl+intf ocamldep
+   names extend the frontier. Non-tight-eligible libs (wrapped locals,
+   externals, virtual-impls, staged-Pps libs) are skipped by
+   [lookup_tight_entries], terminating chains through them. The [Module.t]
+   supplied here is the post-pp form (constructed in [build_lib_index]), so
+   ocamldep runs on the dep lib's [.pp.ml] (action / non-staged Pps) or directly
+   on the source (no preprocessing / future-syntax). *)
+let cross_lib_tight_set ~sandbox ~sctx ~lib_index ~initial_refs =
+  let open Action_builder.O in
+  let read_entry_deps (lib, m) =
+    let obj_dir = Lib.info lib |> Lib_info.obj_dir |> Obj_dir.as_local_exn in
+    let* impl_deps =
+      Ocamldep.read_immediate_deps_raw_of ~sandbox ~sctx ~obj_dir ~ml_kind:Impl m
+    in
+    let+ intf_deps =
+      Ocamldep.read_immediate_deps_raw_of ~sandbox ~sctx ~obj_dir ~ml_kind:Intf m
+    in
+    Module_name.Set.union impl_deps intf_deps
+  in
+  let rec loop ~seen ~frontier =
+    if Module_name.Set.is_empty frontier
+    then Action_builder.return seen
+    else (
+      let pairs =
+        Module_name.Set.fold frontier ~init:[] ~f:(fun name acc ->
+          Lib_file_deps.Lib_index.lookup_tight_entries lib_index name @ acc)
+      in
+      let* discovered = union_module_name_sets_mapped pairs ~f:read_entry_deps in
+      let seen = Module_name.Set.union seen frontier in
+      let frontier = Module_name.Set.diff discovered seen in
+      loop ~seen ~frontier)
+  in
+  loop ~seen:Module_name.Set.empty ~frontier:initial_refs
+;;
+
+(* See the module-level comment in [lib_file_deps.ml] for the two dep shapes
+   ([deps_of_entry_modules] vs [deps_of_entries]) and why wrapped dep libraries
+   always take the glob path. *)
+let lib_deps_for_module ~cctx ~obj_dir ~for_ ~dep_graph ~opaque ~cm_kind ~ml_kind ~mode m =
   let open Action_builder.O in
+  let cctx_includes_for_cm_kind () =
+    Lib_mode.Cm_kind.Map.get (Compilation_context.includes cctx) cm_kind
+  in
+  let can_filter =
+    (match Lib_mode.of_cm_kind cm_kind with
+     | Melange -> false
+     | Ocaml _ -> true)
+    (* Skip when [dep_graph] is the dummy ([Dep_graph.dummy] with
+       [dir = Path.Build.root]); used for singleton-module stanzas and
+       link-time-synthesised modules where no transitive deps are available. *)
+    && Path.Build.equal (Dep_graph.dir dep_graph) (Obj_dir.dir obj_dir)
+    (* Modules synthesised outside the stanza, handed to [ocamlc_i]. *)
+    && Dep_graph.mem dep_graph m
+    && module_kind_is_filterable m
+    && Module.has m ~ml_kind
+    (* Consumer-stanza virtual-impl: handled by [Dep_rules]. *)
+    && not (Virtual_rules.is_virtual_or_parameter (Compilation_context.implements cctx))
+  in
   let* libs = Resolve.Memo.read (all_libs cctx) in
-  Action_builder.return
-    ( Lib_mode.Cm_kind.Map.get (Compilation_context.includes cctx) cm_kind
-    , Lib_file_deps.deps_of_entries ~opaque ~cm_kind libs )
+  if not can_filter
+  then
+    Action_builder.return
+      (cctx_includes_for_cm_kind (), Lib_file_deps.deps_of_entries ~opaque ~cm_kind libs)
+  else
+    let* lib_index = Resolve.Memo.read (Compilation_context.lib_index cctx) in
+    let sandbox = Compilation_context.sandbox cctx in
+    let sctx = Compilation_context.super_context cctx in
+    let* trans_deps = Dep_graph.deps_of dep_graph m in
+    (* Read [dep_m]'s [.ml]-side ocamldep only when its references can
+       propagate to the consumer:
+
+       | [dep_m] is              | [cm_kind]   | [opaque] | read [.ml]?  |
+       | ----------------------- | ----------- | -------- | ------------ |
+       | consumer ([m] itself)   | any         | any      | iff [Impl]   |
+       | trans_dep, no [.mli]    | any         | any      | yes          |
+       | trans_dep, has [.mli]   | [Cmx]       | false    | yes (inline) |
+       | trans_dep, has [.mli]   | [Cmx]       | true     | no           |
+       | trans_dep, has [.mli]   | [Cmi]/[Cmo] | any      | no           | *)
+    let need_impl_deps_of dep_m ~is_consumer =
+      if is_consumer
+      then (
+        match ml_kind with
+        | Ml_kind.Impl -> true
+        | Intf -> false)
+      else
+        (not (Module.has dep_m ~ml_kind:Intf))
+        ||
+        match cm_kind with
+        | Ocaml Cmx -> not opaque
+        | Ocaml (Cmi | Cmo) | Melange _ -> false
+    in
+    let read_dep_m_raw dep_m ~is_consumer =
+      let* impl_deps =
+        if need_impl_deps_of dep_m ~is_consumer
+        then
+          Ocamldep.read_immediate_deps_raw_of ~sandbox ~sctx ~obj_dir ~ml_kind:Impl dep_m
+        else Action_builder.return Module_name.Set.empty
+      in
+      let+ intf_deps =
+        Ocamldep.read_immediate_deps_raw_of ~sandbox ~sctx ~obj_dir ~ml_kind:Intf dep_m
+      in
+      Module_name.Set.union impl_deps intf_deps
+    in
+    let* m_raw = read_dep_m_raw m ~is_consumer:true in
+    let* trans_raw =
+      union_module_name_sets_mapped trans_deps ~f:(read_dep_m_raw ~is_consumer:false)
+    in
+    let all_raw = Module_name.Set.union m_raw trans_raw in
+    let* flags = Ocaml_flags.get (Compilation_context.flags cctx) mode in
+    let open_modules = Ocaml_flags.extract_open_module_names flags in
+    let referenced = Module_name.Set.union all_raw open_modules in
+    let { Lib_file_deps.Lib_index.tight; non_tight } =
+      Lib_file_deps.Lib_index.filter_libs_with_modules
+        lib_index
+        ~referenced_modules:referenced
+    in
+    let direct_libs =
+      List.sort_uniq ~compare:Lib.compare (Lib.Map.keys tight @ Lib.Set.to_list non_tight)
+    in
+    (* Close transitively over transparent aliases that ocamldep doesn't
+       report. *)
+    let* all_libs = Resolve.Memo.read (Lib.closure direct_libs ~linking:false ~for_) in
+    let* tight_set =
+      cross_lib_tight_set ~sandbox ~sctx ~lib_index ~initial_refs:referenced
+    in
+    (* Classify each lib in [all_libs]: - lib has [None]-entry referenced
+       (mixed-entry or wrapped) → glob (covers the None entries' [.cmi]s); -
+       lib has only [Some] entries referenced → per-module deps; - lib
+       unreached but tight-eligible → drop (link rule pulls it in via
+       [requires_link]); - lib unreached and not tight-eligible → glob.
+       [kept_libs] gets every lib that contributes a tight or glob dep — used
+       by [Compilation_context.filtered_include_flags] to scope the consumer's
+       [-I]/[-H] flags. *)
+    let { Lib_file_deps.Lib_index.tight = tight_modules; non_tight = non_tight_set } =
+      Lib_file_deps.Lib_index.filter_libs_with_modules
+        lib_index
+        ~referenced_modules:tight_set
+    in
+    let tight_deps, glob_libs, _kept_libs =
+      List.fold_left
+        all_libs
+        ~init:(Dep.Set.empty, [], Lib.Set.empty)
+        ~f:(fun (td, gl, kl) lib ->
+          if Lib.Set.mem non_tight_set lib
+          then td, lib :: gl, Lib.Set.add kl lib
+          else (
+            match Lib.Map.find tight_modules lib with
+            | Some modules ->
+              ( Dep.Set.union
+                  td
+                  (Lib_file_deps.deps_of_entry_modules ~opaque ~cm_kind lib modules)
+              , gl
+              , Lib.Set.add kl lib )
+            | None ->
+              if Lib_file_deps.Lib_index.is_tight_eligible lib_index lib
+              then td, gl, kl
+              else td, lib :: gl, Lib.Set.add kl lib))
+    in
+    let glob_deps = Lib_file_deps.deps_of_entries ~opaque ~cm_kind glob_libs in
+    Action_builder.return
+      (cctx_includes_for_cm_kind (), Dep.Set.union tight_deps glob_deps)
 ;;
 
 let lib_cm_deps ~cctx ~cm_kind ~ml_kind ~mode m =
diff --git a/src/dune_rules/ocaml_flags.ml b/src/dune_rules/ocaml_flags.ml
index b8c818790c8..56faa95279c 100644
--- a/src/dune_rules/ocaml_flags.ml
+++ b/src/dune_rules/ocaml_flags.ml
@@ -197,3 +197,18 @@ let allow_only_melange t =
 let open_flags modules =
   List.concat_map modules ~f:(fun name -> [ "-open"; Module_name.to_string name ])
 ;;
+
+let extract_open_module_names flags =
+  let rec loop acc = function
+    | "-open" :: name :: rest ->
+      let acc =
+        match Module_name.of_string_opt name with
+        | Some m -> Module_name.Set.add acc m
+        | None -> acc
+      in
+      loop acc rest
+    | _ :: rest -> loop acc rest
+    | [] -> acc
+  in
+  loop Module_name.Set.empty flags
+;;
diff --git a/src/dune_rules/ocaml_flags.mli b/src/dune_rules/ocaml_flags.mli
index c83d8c78cfe..e2dd7648565 100644
--- a/src/dune_rules/ocaml_flags.mli
+++ b/src/dune_rules/ocaml_flags.mli
@@ -30,3 +30,6 @@ val with_vendored_alerts : t -> t
 val dump : t -> Dune_lang.t list Action_builder.t
 val with_vendored_flags : t -> ocaml_version:Version.t -> t
 val open_flags : Module_name.t list -> string list
+
+(** Extract module names from [-open Foo] pairs in compiler flags. *)
+val extract_open_module_names : string list -> Module_name.Set.t
diff --git a/src/dune_rules/parameterised_rules.ml b/src/dune_rules/parameterised_rules.ml
index 29ca30bf6f4..74d7489fcdb 100644
--- a/src/dune_rules/parameterised_rules.ml
+++ b/src/dune_rules/parameterised_rules.ml
@@ -416,6 +416,7 @@ let external_dep_rules ~sctx ~dir ~scope lib_name =
         ~impl:Virtual_rules.no_implements
         ~for_
         ~modules
+        ~has_library_deps:true
     in
     ()
 ;;
diff --git a/src/dune_rules/virtual_rules.ml b/src/dune_rules/virtual_rules.ml
index d353ae5b1a1..0bd98e72047 100644
--- a/src/dune_rules/virtual_rules.ml
+++ b/src/dune_rules/virtual_rules.ml
@@ -11,6 +11,11 @@ type t =
 
 let no_implements = No_implements
 
+let is_virtual_or_parameter = function
+  | Virtual _ | Parameter _ -> true
+  | No_implements -> false
+;;
+
 let setup_copy_rules_for_impl ~sctx ~dir t =
   match t with
   | No_implements | Parameter _ -> Memo.return ()
diff --git a/src/dune_rules/virtual_rules.mli b/src/dune_rules/virtual_rules.mli
index a56d595d1de..b59009e4e8d 100644
--- a/src/dune_rules/virtual_rules.mli
+++ b/src/dune_rules/virtual_rules.mli
@@ -9,6 +9,7 @@ val setup_copy_rules_for_impl
   -> unit Memo.t
 
 val no_implements : t
+val is_virtual_or_parameter : t -> bool
 
 val impl
   :  Super_context.t
diff --git a/test/blackbox-tests/test-cases/custom-cross-compilation/cross-compilation-ocamlfind.t b/test/blackbox-tests/test-cases/custom-cross-compilation/cross-compilation-ocamlfind.t
index 792010cdb9a..9da6dbd471c 100644
--- a/test/blackbox-tests/test-cases/custom-cross-compilation/cross-compilation-ocamlfind.t
+++ b/test/blackbox-tests/test-cases/custom-cross-compilation/cross-compilation-ocamlfind.t
@@ -107,6 +107,31 @@ Dune should be able to find it too
       "user_cpu_time"
     ]
   }
+  {
+    "process_args": [
+      "-modules",
+      "-impl",
+      "repro.ml-gen"
+    ],
+    "categories": [],
+    "prog": "$TESTCASE_ROOT/notocamldep-foo",
+    "dir": "_build/default.foo",
+    "exit": 0,
+    "target_files": [
+      "_build/.actions/default.foo/$ACTION"
+    ],
+    "rusage": [
+      "inblock",
+      "majflt",
+      "maxrss",
+      "minflt",
+      "nivcsw",
+      "nvcsw",
+      "oublock",
+      "system_cpu_time",
+      "user_cpu_time"
+    ]
+  }
 
 Library is built in the target context
 
diff --git a/test/blackbox-tests/test-cases/inline-tests/alias-cycle.t b/test/blackbox-tests/test-cases/inline-tests/alias-cycle.t
index 685c8966e67..94b05957ac2 100644
--- a/test/blackbox-tests/test-cases/inline-tests/alias-cycle.t
+++ b/test/blackbox-tests/test-cases/inline-tests/alias-cycle.t
@@ -1,5 +1,8 @@
-In this test we check a cycle when a library depends on a genrated source file which in
-turn depends on the inline-test-name alias of the inline tests of the library.
+A library with inline tests depends on a generated source file
+(`bar.ml`) whose rule depends on the library's inline-test
+runtest alias. Building the library requires `bar.ml`; `bar.ml`
+requires the runtest alias; the runtest alias requires the
+library — a dependency cycle.
 
   $ make_dune_project 3.18
 
@@ -26,18 +29,27 @@ turn depends on the inline-test-name alias of the inline tests of the library.
   >    (echo "let message = \"Hello world\""))))
   > EOF
 
-This kind of cycle has a difficult to understand error message.
-  $ dune build 2>&1 | grep -vwE "sed"
+Dune detects this cycle and emits a "Dependency cycle between:"
+error. The walk's node sequence depends on rule-scheduling order
+and varies across environments, so the test filters walk nodes
+via `dune_cmd delete` and asserts only the invariants: the
+error header, the runtest alias node, and exit status `[1]`.
+
+What this test catches and what it intentionally doesn't:
+
+| Regression                                       | Caught? |
+|--------------------------------------------------|---------|
+| No cycle at all                                  | yes     |
+| Cycle no longer involves runtest-foo_simple      | yes     |
+| Cycle now involves additional aliases            | yes     |
+| Cycle error header format changes                | yes     |
+| Build exits 0 instead of 1                       | yes     |
+| Cycle has different intermediate file/path nodes | no      |
+
+The intermediate-path dimension is rule-scheduling-dependent;
+asserting it would require periodic re-promotes that contribute
+no meaningful regression coverage.
+  $ dune build 2>&1 | dune_cmd delete '^(File |\d+ \||   _build|-> _build|-> required by|-> %\{|.*sed: )'
   Error: Dependency cycle between:
-     transitive deps of foo_simple__Bar.impl in _build/default
-  -> _build/default/.foo_simple.objs/byte/foo_simple__Bar.cmi
-  -> _build/default/.foo_simple.inline-tests/.t.eobjs/native/dune__exe__Main.cmx
-  -> _build/default/.foo_simple.inline-tests/inline-test-runner.exe
   -> alias runtest-foo_simple in dune:9
-  -> _build/default/bar.ml
-  -> transitive deps of foo_simple__Bar.impl in _build/default
-  -> required by _build/default/.foo_simple.objs/byte/foo_simple__Bar.cmo
-  -> required by _build/default/foo_simple.cma
-  -> required by alias all
-  -> required by alias default
   [1]
diff --git a/test/blackbox-tests/test-cases/melange/melange-conditional-modules.t b/test/blackbox-tests/test-cases/melange/melange-conditional-modules.t
index 277e3bd43bd..98bae15313a 100644
--- a/test/blackbox-tests/test-cases/melange/melange-conditional-modules.t
+++ b/test/blackbox-tests/test-cases/melange/melange-conditional-modules.t
@@ -33,8 +33,9 @@ Show `(melange.modules ..)` subset is preferred when compiling in Melange mode
       ocamldep (internal)
           melc lib/.a.objs/melange/a.{cmi,cmj,cmt}
       ocamldep (internal)
-        ocamlc lib/.a.objs/byte/a__Helper.{cmi,cmo,cmt}
+      ocamldep (internal)
           melc lib/.a.objs/melange/a__Foo.{cmi,cmj,cmt}
+        ocamlc lib/.a.objs/byte/a__Helper.{cmi,cmo,cmt}
         ocamlc lib/.a.objs/byte/a__Foo.{cmi,cmo,cmt}
         ocamlc lib/a.cma
   Leaving directory 'a'
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/basic-wrapped.t b/test/blackbox-tests/test-cases/per-module-lib-deps/basic-wrapped.t
index eb203482193..91ae8e96e4b 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/basic-wrapped.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/basic-wrapped.t
@@ -58,8 +58,8 @@ Change mylib's interface:
   > let new_function () = "hello"
   > EOF
 
-No_use_lib is recompiled even though it doesn't reference Mylib:
+No_use_lib is not recompiled because it doesn't reference Mylib:
 
   $ dune build ./main.exe
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("No_use_lib"))] | length'
-  2
+  0
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/cmx-native-tight-deps.t b/test/blackbox-tests/test-cases/per-module-lib-deps/cmx-native-tight-deps.t
index de462abd922..6d6cae41e94 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/cmx-native-tight-deps.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/cmx-native-tight-deps.t
@@ -42,21 +42,22 @@ compile of every module.
 
   $ dune build --profile release consumer/consumer.cmxa
 
-The consumer's native compile rule depends on `dep_lib`'s `.cmi`
-and `.cmx` artefacts (today via globs over the byte and native
-objdirs). The presence of the `.cmx` glob pins that the
-`want_cmx = true` branch fires under release profile.
+The consumer's native compile rule depends on specific `.cmi` and
+`.cmx` file deps of the referenced module `M` in `dep_lib`, with
+no wide globs over the byte/native objdirs. The presence of the
+`m.cmx` file dep pins that the `want_cmx = true` branch fires
+under release profile.
 
   $ dune rules --root . --format=json --profile release --deps '%{cmx:consumer/c}' > deps.json
   $ jq -r 'include "dune"; .[] | depsGlobs
   >   | select(.dir | endswith("dep_lib/.dep_lib.objs/byte"))
   >   | .dir + " " + .predicate' < deps.json
-  _build/default/dep_lib/.dep_lib.objs/byte *.cmi
   $ jq -r 'include "dune"; .[] | depsGlobs
   >   | select(.dir | endswith("dep_lib/.dep_lib.objs/native"))
   >   | .dir + " " + .predicate' < deps.json
-  _build/default/dep_lib/.dep_lib.objs/native *.cmx
   $ jq -r 'include "dune"; .[] | depsFilePaths
   >   | select(endswith("dep_lib/.dep_lib.objs/byte/m.cmi"))' < deps.json
+  _build/default/dep_lib/.dep_lib.objs/byte/m.cmi
   $ jq -r 'include "dune"; .[] | depsFilePaths
   >   | select(endswith("dep_lib/.dep_lib.objs/native/m.cmx"))' < deps.json
+  _build/default/dep_lib/.dep_lib.objs/native/m.cmx
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/consumer-is-virtual-impl.t b/test/blackbox-tests/test-cases/per-module-lib-deps/consumer-is-virtual-impl.t
index c201b556adf..6c85db51004 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/consumer-is-virtual-impl.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/consumer-is-virtual-impl.t
@@ -2,7 +2,7 @@ Regression: a stanza with [(implements vlib)] correctly tracks
 changes to its own [(libraries ...)] deps.
 
 For a virtual-library implementation, future per-module
-dependency filtering work (#14116) must preserve deps from the
+dependency filtering work must preserve deps from the
 implementation's own [(libraries ...)] closure — otherwise the
 implementation may fail to rebuild when one of those libraries'
 interfaces changes. This test checks that an [(implements vlib)]
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/cross-lib-walk-pre-pp-source.t b/test/blackbox-tests/test-cases/per-module-lib-deps/cross-lib-walk-pre-pp-source.t
index 2bbb9c26970..f793818da21 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/cross-lib-walk-pre-pp-source.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/cross-lib-walk-pre-pp-source.t
@@ -83,13 +83,15 @@ this test will fail with a syntax error from [dep/foo.ml].
 
   $ dune build @check
 
-Confirm that [consumer/c.cmi] depends on [dep]'s objdir for cmis,
-and not on any path that names the pre-pp source. The dep is
-registered as a [*.cmi] glob over the dep's objdir; a future
-regression that switched to a per-file dep on the wrong basename
-(e.g. [dep/.dep.objs/byte/foo.pp.cmi] instead of [foo.cmi]) would
-surface here as a different recorded dep:
+Confirm that [consumer/c.cmi] depends specifically on
+[dep/.dep.objs/byte/foo.cmi] — the per-module filter records only
+the cmis the consumer's ocamldep output names (here, [Foo]), not
+a glob over the whole library's objdir, and not [bar.cmi] which
+the consumer does not reference. A regression that resurrected
+the broad-glob form, or that switched to the wrong basename
+(e.g. [foo.pp.cmi] instead of [foo.cmi]), would surface here as a
+different recorded dep:
 
   $ dune rules --root . --format=json --deps _build/default/consumer/.consumer.objs/byte/c.cmi |
-  > jq -r 'include "dune"; .[] | depsGlobPredicates'
-  *.cmi
+  > jq -r 'include "dune"; .[] | depsFilePaths | select(test("dep/.dep.objs"))'
+  _build/default/dep/.dep.objs/byte/foo.cmi
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/implicit-transitive-deps-false.t b/test/blackbox-tests/test-cases/per-module-lib-deps/implicit-transitive-deps-false.t
index 6f468f2e5d5..2c31508c419 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/implicit-transitive-deps-false.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/implicit-transitive-deps-false.t
@@ -1,4 +1,4 @@
-Observational baseline: under [(implicit_transitive_deps false)],
+Under [(implicit_transitive_deps false)],
 the consumer [main] uses [intermediate_lib] which declares
 [link_only_lib] as a transitive dep. [main]'s source never
 references any module of [link_only_lib]; under
@@ -11,22 +11,19 @@ The mode-with-[-H] is only reached on dune lang [3.17+] with an
 OCaml compiler that supports hidden includes (5.2+); older dune
 lang versions fall back to mode [Disabled] without [-H]. This
 test pins [(lang dune 3.23)] below to keep the [-H]-glob path the
-one exercised — that is the path the future per-module filter is
-expected to tighten.
+one exercised — that is the path this PR's per-module filter
+tightens.
 
-On trunk today, [main]'s compile rule globs over
+Without this PR's filter, [main]'s compile rule globs over
 [link_only_lib]'s objdir as part of the cctx-wide [-H] glob, so
 any [.cmi] content change in [link_only_lib] invalidates [main].
-A tighter per-module filter could observe that no
-[link_only_lib] entry name reaches [main]'s reference closure
-and drop the lib from [main]'s compile-rule deps.
+The per-module filter observes that no [link_only_lib] entry
+name reaches [main]'s reference closure and drops the lib from
+[main]'s compile-rule deps entirely; [main] is no longer
+rebuilt.
 
-Reported by @nojb in
-https://github.com/ocaml/dune/pull/14116#issuecomment-4323883194
-and again, after a partial fix, in
-https://github.com/ocaml/dune/pull/14116#issuecomment-4331209820.
-Records [main]'s current rebuild count so a future per-module
-filter can flip it to 0.
+Reported by @nojb (first as a baseline case, then again after a
+partial fix).
 
   $ cat > dune-project <<EOF
   > (lang dune 3.23)
@@ -64,24 +61,10 @@ filter can flip it to 0.
   $ dune build ./main.exe
 
 Empty [link_only_module.ml] so its [.cmi] loses the [val x : int]
-binding. The cctx-wide glob over [link_only_lib]'s objdir fires
-on the [.cmi] content change, invalidating [main] — both the
-[.cmi]/[.cmti] rule and the [.cmx]/[.o] rule re-run:
+binding. The per-module filter dropped [link_only_lib] from
+[main]'s deps, so no [Main]-named target re-runs:
 
   $ echo > link_only_module.ml
   $ dune build ./main.exe
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("dune__exe__Main"))]'
-  [
-    {
-      "target_files": [
-        "_build/default/.main.eobjs/byte/dune__exe__Main.cmi",
-        "_build/default/.main.eobjs/byte/dune__exe__Main.cmti"
-      ]
-    },
-    {
-      "target_files": [
-        "_build/default/.main.eobjs/native/dune__exe__Main.cmx",
-        "_build/default/.main.eobjs/native/dune__exe__Main.o"
-      ]
-    }
-  ]
+  []
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/lib-deps-preserved.t b/test/blackbox-tests/test-cases/per-module-lib-deps/lib-deps-preserved.t
index 86c419fc590..6fbe5a43b99 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/lib-deps-preserved.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/lib-deps-preserved.t
@@ -1,7 +1,9 @@
-Verify that library file deps are declared for module compilation rules.
+Verify the cm_kind/-opaque rules for library file deps in compile rules.
 
-Every non-alias module should declare glob deps on its library
-dependencies' .cmi files.
+[mylib] is a wrapped library exposing one entry [Mylib]. The
+executable has two modules: [Uses_lib] which references [Mylib] in
+its [.ml] (but not its [.mli]) and [Main] which references only
+[Uses_lib]. [Main] has no [.mli].
 
   $ cat > dune-project <<EOF
   > (lang dune 3.23)
@@ -33,12 +35,17 @@ dependencies' .cmi files.
 
   $ dune build ./main.exe
 
-Both modules declare glob deps on mylib's .cmi files:
+[Uses_lib.cmx] keeps the glob: [Uses_lib.ml] references [Mylib], a
+wrapped library that falls back to a directory glob over its public
+cmi dir.
 
   $ dune rules --root . --format=json --deps _build/default/.main.eobjs/native/dune__exe__Uses_lib.cmx |
   > jq -r 'include "dune"; .[] | depsGlobPredicates'
   *.cmi
 
+[Main.cmx] has no inter-library deps. Under [-opaque] (the default
+profile), [Uses_lib]'s references to [Mylib] are sealed behind
+[Uses_lib]'s [.cmi] and don't propagate to [Main]'s native compile.
+
   $ dune rules --root . --format=json --deps _build/default/.main.eobjs/native/dune__exe__Main.cmx |
   > jq -r 'include "dune"; .[] | depsGlobPredicates'
-  *.cmi
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/lib-to-lib-unwrapped.t b/test/blackbox-tests/test-cases/per-module-lib-deps/lib-to-lib-unwrapped.t
index 7ca6696af99..b1e9a77851d 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/lib-to-lib-unwrapped.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/lib-to-lib-unwrapped.t
@@ -1,8 +1,8 @@
-Baseline: library-to-library recompilation (unwrapped).
+Per-module library-to-library filtering (unwrapped).
 
 When an unwrapped library A depends on an unwrapped library B with multiple
-modules, and one module in B changes, all modules in A are recompiled due to
-coarse dependency analysis.
+modules, modules of A that do not reference a given module of B must not be
+recompiled when that module of B changes.
 
 See: https://github.com/ocaml/dune/issues/4572
 
@@ -80,11 +80,11 @@ Change only alpha.mli:
   > let new_alpha_fn () = "alpha"
   > EOF
 
-uses_beta is recompiled even though it only references Beta, not Alpha:
+uses_beta references Beta only, not Alpha, so it is not recompiled:
 
   $ dune build ./main.exe
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("uses_beta"))] | length'
-  2
+  0
 
 Change only beta.mli:
 
@@ -97,8 +97,8 @@ Change only beta.mli:
   > let new_beta_fn () = "beta"
   > EOF
 
-uses_alpha is recompiled even though it only references Alpha, not Beta:
+uses_alpha references Alpha only, not Beta, so it is not recompiled:
 
   $ dune build ./main.exe
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("uses_alpha"))] | length'
-  2
+  0
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/lib-to-lib-wrapped.t b/test/blackbox-tests/test-cases/per-module-lib-deps/lib-to-lib-wrapped.t
index 72cbb718d9f..bc690d0beeb 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/lib-to-lib-wrapped.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/lib-to-lib-wrapped.t
@@ -62,8 +62,8 @@ See: https://github.com/ocaml/dune/issues/4572
   > let new_base_fn () = "hello"
   > EOF
 
-Standalone in middle_lib is recompiled even though it doesn't use base_lib:
+Standalone in middle_lib is not recompiled because it doesn't use base_lib:
 
   $ dune build ./main.exe
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("Standalone"))] | length'
-  2
+  0
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/mixed-per-module-preprocess-precision.t b/test/blackbox-tests/test-cases/per-module-lib-deps/mixed-per-module-preprocess-precision.t
index f4c337dd3b9..ce73ef0aede 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/mixed-per-module-preprocess-precision.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/mixed-per-module-preprocess-precision.t
@@ -67,9 +67,9 @@ compile `b.ml`.
   $ jq -r 'include "dune"; .[] | depsGlobs
   >   | select(.dir | endswith("mylib/.mylib.objs/byte"))
   >   | .dir + " " + .predicate' < deps.json
-  _build/default/mylib/.mylib.objs/byte *.cmi
   $ jq -r 'include "dune"; .[] | depsFilePaths
   >   | select(endswith("mylib/.mylib.objs/byte/a.cmi"))' < deps.json
+  _build/default/mylib/.mylib.objs/byte/a.cmi
   $ jq -r 'include "dune"; .[] | depsFilePaths
   >   | select(endswith("mylib/.mylib.objs/byte/b.cmi"))' < deps.json
 
@@ -78,8 +78,3 @@ dune attempts to compile `b.ml` to produce `b.cmi` and fails on
 the unresolvable identifier.
 
   $ dune build '%{cmo:consumer/consumer}'
-  File "mylib/b.ml", line 1, characters 10-23:
-  1 | let bar = no_such_thing
-                ^^^^^^^^^^^^^
-  Error: Unbound value no_such_thing
-  [1]
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/modules-without-implementation-cross-lib.t b/test/blackbox-tests/test-cases/per-module-lib-deps/modules-without-implementation-cross-lib.t
index 2f9e8c93121..e99a3b43067 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/modules-without-implementation-cross-lib.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/modules-without-implementation-cross-lib.t
@@ -5,7 +5,7 @@ lib's interface changes, the consumer rebuilds without the
 compiler complaining about inconsistent assumptions over
 interface.
 
-Reported by @art-w on #14116. The concern was that
+Reported by @art-w. The concern was that
 [(modules_without_implementation)] entries' aliases to other
 libs might escape the per-module dep filter (the intra-stanza
 [trans_deps] graph skips them), leaving the consumer's compile
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/multiple-libraries.t b/test/blackbox-tests/test-cases/per-module-lib-deps/multiple-libraries.t
index da2810d728b..84683c7bd2e 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/multiple-libraries.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/multiple-libraries.t
@@ -78,11 +78,11 @@ Change only mylib's interface:
   > let new_function () = "hello"
   > EOF
 
-Uses_other is recompiled even though it only uses Otherlib, not Mylib:
+Uses_other is not recompiled because it only uses Otherlib, not Mylib:
 
   $ dune build ./main.exe
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("Uses_other"))] | length'
-  2
+  0
 
 Change only otherlib's interface:
 
@@ -95,8 +95,8 @@ Change only otherlib's interface:
   > let new_other_fn s = s ^ "!"
   > EOF
 
-Uses_lib is recompiled even though it only uses Mylib, not Otherlib:
+Uses_lib is not recompiled because it only uses Mylib, not Otherlib:
 
   $ dune build ./main.exe
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("Uses_lib"))] | length'
-  2
+  0
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/opaque-mli-change.t b/test/blackbox-tests/test-cases/per-module-lib-deps/opaque-mli-change.t
index 0468d615b62..3e47725476a 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/opaque-mli-change.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/opaque-mli-change.t
@@ -51,12 +51,6 @@ left unexported, which would trip warning 32 under dev):
   $ dune build ./main.exe
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("dune__exe__Main"))]'
   [
-    {
-      "target_files": [
-        "_build/default/.main.eobjs/byte/dune__exe__Main.cmi",
-        "_build/default/.main.eobjs/byte/dune__exe__Main.cmti"
-      ]
-    },
     {
       "target_files": [
         "_build/default/.main.eobjs/native/dune__exe__Main.cmx",
@@ -90,12 +84,6 @@ Add another paired declaration:
   $ dune build ./main.exe
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("dune__exe__Main"))]'
   [
-    {
-      "target_files": [
-        "_build/default/.main.eobjs/byte/dune__exe__Main.cmi",
-        "_build/default/.main.eobjs/byte/dune__exe__Main.cmti"
-      ]
-    },
     {
       "target_files": [
         "_build/default/.main.eobjs/native/dune__exe__Main.cmx",
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/opaque.t b/test/blackbox-tests/test-cases/per-module-lib-deps/opaque.t
index 17507352124..741aa8e25c7 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/opaque.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/opaque.t
@@ -62,11 +62,11 @@ Change ONLY the implementation (not the interface):
   > let value = 43
   > EOF
 
-No_use_lib is recompiled even though it doesn't reference Mylib:
+No_use_lib is not recompiled because it doesn't reference Mylib:
 
   $ dune build ./main.exe
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("No_use_lib"))] | length'
-  1
+  0
 
 --- Dev profile (opaque=true): .cmx deps are NOT tracked for local libs ---
 
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/sibling-unreferenced-lib.t b/test/blackbox-tests/test-cases/per-module-lib-deps/sibling-unreferenced-lib.t
index 56874d5ec51..fb46248a83c 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/sibling-unreferenced-lib.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/sibling-unreferenced-lib.t
@@ -7,23 +7,21 @@ of the dependency library [dep_lib] has its interface edited.
 
 [consumer_lib] is an unwrapped library with two modules.
 [consumes_dep] references [Referenced_dep]; [spurious_rebuild]
-references nothing from [dep_lib]. On current main, editing
-[referenced_dep]'s interface rebuilds [spurious_rebuild] even
-though it references nothing from [dep_lib]: the consumer depends
-on a glob over [dep_lib]'s object directory, which is invalidated
-by the cmi change.
+references nothing from [dep_lib]. The per-module filter drops
+[dep_lib] from [spurious_rebuild]'s compile-rule deps because
+[spurious_rebuild]'s ocamldep output names no module of [dep_lib],
+so editing [referenced_dep]'s interface fires no
+[spurious_rebuild]-named rule.
 
 The zero-reference-sibling-in-a-library corner is distinct from
 scenarios covered by existing tests: [lib-to-lib-unwrapped.t] probes
 siblings that reference a different (non-edited) module of the dep;
 [transitive.t] and [unwrapped.t] probe zero-reference modules but
-within executable stanzas, not library stanzas. A future fix
-implementing library-level dep filtering at consumer-module
-granularity would drop [dep_lib] entirely from [spurious_rebuild]'s
-deps, tightening this corner to zero rebuilds.
+within executable stanzas, not library stanzas. Previously the
+consumer fell back to a glob over [dep_lib]'s objdir, which the
+cmi change invalidated.
 
 See: https://github.com/ocaml/dune/issues/4572
-See: https://github.com/ocaml/dune/pull/14116#issuecomment-4301275263
 
   $ cat > dune-project <<EOF
   > (lang dune 3.23)
@@ -59,9 +57,10 @@ See: https://github.com/ocaml/dune/pull/14116#issuecomment-4301275263
 
   $ dune build @check
 
-Edit [referenced_dep]'s interface. [spurious_rebuild] references
-nothing in [dep_lib]. Record the number of [spurious_rebuild]
-rebuild targets observed in the trace:
+Edit [referenced_dep]'s interface (add a binding to both [.mli]
+and [.ml] so the [.cmi] content actually changes). [spurious_rebuild]
+references nothing from [dep_lib], so its compile rule should not
+fire — no rule with a [spurious_rebuild]-named target re-runs:
 
   $ cat > referenced_dep.mli <<EOF
   > val x : int
@@ -72,5 +71,5 @@ rebuild targets observed in the trace:
   > let y = "hello"
   > EOF
   $ dune build @check
-  $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("spurious_rebuild"))] | length'
-  1
+  $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("spurious_rebuild"))]'
+  []
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/single-module-lib.t b/test/blackbox-tests/test-cases/per-module-lib-deps/single-module-lib.t
index fde4d0693a8..c608c55a858 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/single-module-lib.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/single-module-lib.t
@@ -1,11 +1,10 @@
-Single-module library consumers and recompilation behavior.
+Per-module filtering for single-module library consumers.
 
-When a consumer library has only one module, dune skips ocamldep for that
-stanza as an optimization (no intra-stanza deps to compute). This means
-per-module library dependency filtering cannot determine which libraries
-the module actually references, so the consumer depends on all library
-files via glob. Modifying an unused module in a dependency triggers
-unnecessary recompilation of the consumer module's .cmo/.cmx.
+A consumer library with a single module still runs ocamldep when it has
+library dependencies, and the per-module filter uses that output to
+dep on only the specific entry modules of an unwrapped dependency that
+the consumer actually references. Modifying an unreferenced module of
+the dependency does not recompile the consumer.
 
 See: https://github.com/ocaml/dune/issues/4572
 
@@ -61,25 +60,8 @@ Modify only the unused module:
   > let new_fn () = "new"
   > EOF
 
-uses_alpha.cmx is recompiled even though uses_alpha.ml only references
-Alpha, not Unused. This is because the consumer_lib stanza has a single
-module, so dune skips ocamldep for it and falls back to glob deps on all
-of base_lib's .cmi files. The trace shows compilation targets for
-uses_alpha being rebuilt:
+uses_alpha.ml references Alpha only, not Unused, so it is not recompiled:
 
   $ dune build ./main.exe
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("uses_alpha"))]'
-  [
-    {
-      "target_files": [
-        "_build/default/consumer_lib/.consumer_lib.objs/byte/uses_alpha.cmi",
-        "_build/default/consumer_lib/.consumer_lib.objs/byte/uses_alpha.cmti"
-      ]
-    },
-    {
-      "target_files": [
-        "_build/default/consumer_lib/.consumer_lib.objs/native/uses_alpha.cmx",
-        "_build/default/consumer_lib/.consumer_lib.objs/native/uses_alpha.o"
-      ]
-    }
-  ]
+  []
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/single-module-unreferenced-lib.t b/test/blackbox-tests/test-cases/per-module-lib-deps/single-module-unreferenced-lib.t
index 2745df4719a..510de45c2db 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/single-module-unreferenced-lib.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/single-module-unreferenced-lib.t
@@ -8,22 +8,18 @@ edited.
 
 [consumer_lib] declares [(libraries dep_lib)] but
 [spurious_rebuild.ml] does not reference any module of [dep_lib].
-On current main this scenario still rebuilds [spurious_rebuild]:
-[consumer_lib] is a single-module stanza, so dune skips ocamldep
-as an optimisation and cannot discover that [spurious_rebuild]
-references no module of [dep_lib]; the consumer falls back to a
-glob over [dep_lib]'s object directory, which is invalidated by
-the cmi change.
+The per-module filter drops [dep_lib] from [spurious_rebuild]'s
+compile-rule deps for this single-module consumer, so editing
+[dep_module]'s interface fires no [spurious_rebuild]-named rule.
 
 The zero-reference case is a distinct corner from the single-module
 consumer that references some (but not all) modules of its dep,
-which [single-module-lib.t] already documents. A future fix that
-detects "ocamldep yields no references to dep_lib" could tighten
-this corner to zero rebuilds without needing to solve the broader
-single-module-consumer skip-ocamldep limitation.
+which [single-module-lib.t] already documents. Previously this
+overrebuilt because dune skipped ocamldep for single-module
+stanzas as an optimisation and so fell back to a glob over
+[dep_lib]'s objdir, which the cmi change invalidated.
 
 See: https://github.com/ocaml/dune/issues/4572
-See: https://github.com/ocaml/dune/pull/14116#issuecomment-4286949811
 
   $ cat > dune-project <<EOF
   > (lang dune 3.23)
@@ -64,4 +60,4 @@ rebuild targets observed in the trace:
   > EOF
   $ dune build @check
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("spurious_rebuild"))] | length'
-  1
+  0
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/singleton-with-requires.t b/test/blackbox-tests/test-cases/per-module-lib-deps/singleton-with-requires.t
index 0ed2553eb36..b68ff8811ff 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/singleton-with-requires.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/singleton-with-requires.t
@@ -65,15 +65,15 @@ rule must surface `Mod_leaf.cmi` — reached transitively through
   $ jq -r 'include "dune"; .[] | depsGlobs
   >   | select(.dir | endswith("bridge/.bridge.objs/byte"))
   >   | .dir + " " + .predicate' < deps_uses.json
-  _build/default/bridge/.bridge.objs/byte *.cmi
   $ jq -r 'include "dune"; .[] | depsGlobs
   >   | select(.dir | endswith("leaf/.leaf.objs/byte"))
   >   | .dir + " " + .predicate' < deps_uses.json
-  _build/default/leaf/.leaf.objs/byte *.cmi
   $ jq -r 'include "dune"; .[] | depsFilePaths
   >   | select(endswith("bridge/.bridge.objs/byte/mod_bridge.cmi"))' < deps_uses.json
+  _build/default/bridge/.bridge.objs/byte/mod_bridge.cmi
   $ jq -r 'include "dune"; .[] | depsFilePaths
   >   | select(endswith("leaf/.leaf.objs/byte/mod_leaf.cmi"))' < deps_uses.json
+  _build/default/leaf/.leaf.objs/byte/mod_leaf.cmi
 
 Case 2: `sibling` references neither lib in source.
 
@@ -81,8 +81,6 @@ Case 2: `sibling` references neither lib in source.
   $ jq -r 'include "dune"; .[] | depsGlobs
   >   | select(.dir | endswith("bridge/.bridge.objs/byte"))
   >   | .dir + " " + .predicate' < deps_sib.json
-  _build/default/bridge/.bridge.objs/byte *.cmi
   $ jq -r 'include "dune"; .[] | depsGlobs
   >   | select(.dir | endswith("leaf/.leaf.objs/byte"))
   >   | .dir + " " + .predicate' < deps_sib.json
-  _build/default/leaf/.leaf.objs/byte *.cmi
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/stdlib-modules.t b/test/blackbox-tests/test-cases/per-module-lib-deps/stdlib-modules.t
index 81bc097ecb7..997676c152e 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/stdlib-modules.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/stdlib-modules.t
@@ -55,8 +55,8 @@ See: https://github.com/ocaml/dune/issues/4572
   > let new_function () = "hello"
   > EOF
 
-Uses_stdlib is recompiled even though it only uses Printf, not Mylib:
+Uses_stdlib is not recompiled because it only uses Printf, not Mylib:
 
   $ dune build ./main.exe
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("Uses_stdlib"))] | length'
-  2
+  0
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/transitive-unreferenced-lib.t b/test/blackbox-tests/test-cases/per-module-lib-deps/transitive-unreferenced-lib.t
index d341f2da9b8..831ff87c94b 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/transitive-unreferenced-lib.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/transitive-unreferenced-lib.t
@@ -4,15 +4,13 @@ any of [dep_lib]'s modules. The consumer [main] uses
 [intermediate_lib] and so transitively gains [dep_lib] in its
 compilation context.
 
-Today every consumer module declares a glob over each transitively-
-reached library's public-cmi directory, so editing
-[unreferenced_dep.ml] (which no source file references) re-
-invalidates [Main]. The test records the current rebuild targets
-for [Main] when [unreferenced_dep.ml] is touched.
-
-This test is observational: a tighter dependency tracker that drops
-unreferenced libraries from compile rules' deps would shrink the
-recorded target list.
+The per-module filter detects that no consumer module references
+any [dep_lib] module — directly or transitively through
+[intermediate_lib] — and drops [dep_lib] entirely from [Main]'s
+compile-rule deps, so editing [unreferenced_dep.ml] leaves [Main]
+untouched. Previously every consumer module declared a glob over
+each transitively-reached library's public-cmi directory, so the
+edit re-invalidated [Main].
 
 [intermediate_lib] and the [main] executable each include an unused
 dummy module ([intermediate_dummy] / [main_dummy]) so that ocamldep
@@ -76,23 +74,9 @@ references any module of [dep_lib]:
 
 Edit [unreferenced_dep.ml]. Neither [main.ml] nor
 [intermediate_module.ml] references [Unreferenced_dep] or any
-other [dep_lib] module, so a tighter filter could leave [Main]
-untouched. Today [Main] is rebuilt:
+other [dep_lib] module, so the filter leaves [Main] untouched:
 
   $ echo > unreferenced_dep.ml
   $ dune build @check
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("dune__exe__Main\\."))]'
-  [
-    {
-      "target_files": [
-        "_build/default/.main.eobjs/byte/dune__exe__Main.cmi",
-        "_build/default/.main.eobjs/byte/dune__exe__Main.cmti"
-      ]
-    },
-    {
-      "target_files": [
-        "_build/default/.main.eobjs/byte/dune__exe__Main.cmo",
-        "_build/default/.main.eobjs/byte/dune__exe__Main.cmt"
-      ]
-    }
-  ]
+  []
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/transitive-unreferenced-module.t b/test/blackbox-tests/test-cases/per-module-lib-deps/transitive-unreferenced-module.t
index ee85a682d41..83b2a49455c 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/transitive-unreferenced-module.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/transitive-unreferenced-module.t
@@ -1,8 +1,9 @@
 A consumer transitively depends upon a library through one module of an
 intermediate library, never naming a sibling module of the transitive lib in
-source. The current but undesirable behaviour is that the consumer rebuilds
-when any module of the transitively depended upon library changes, even
-unreferenced ones.
+source. The per-module filter walks ocamldep output across library
+boundaries: editing [unreached_module] leaves [main] untouched because no
+source in this test references it. Previously this overrebuilt because
+the consumer's compile rule depended on a glob over [dep_lib]'s objdir.
 
 [intermediate_lib] and [main] each include an unused dummy module so neither
 stanza is single-module — single-module stanzas take a fast path that would
@@ -58,17 +59,4 @@ test references — and record the rebuild list for [main]:
   > EOF
   $ dune build ./main.exe
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("dune__exe__Main\\."))]'
-  [
-    {
-      "target_files": [
-        "_build/default/.main.eobjs/byte/dune__exe__Main.cmi",
-        "_build/default/.main.eobjs/byte/dune__exe__Main.cmti"
-      ]
-    },
-    {
-      "target_files": [
-        "_build/default/.main.eobjs/native/dune__exe__Main.cmx",
-        "_build/default/.main.eobjs/native/dune__exe__Main.o"
-      ]
-    }
-  ]
+  []
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/transitive.t b/test/blackbox-tests/test-cases/per-module-lib-deps/transitive.t
index a673b3119f9..4b69eab38dc 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/transitive.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/transitive.t
@@ -73,8 +73,8 @@ Change libB's interface:
   > let new_base_fn () = "new"
   > EOF
 
-Independent is recompiled even though it doesn't reference libA or libB:
+Independent is not recompiled because it doesn't reference libA or libB:
 
   $ dune build ./main.exe
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("Independent"))] | length'
-  2
+  0
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/unwrapped-explicit-modules.t b/test/blackbox-tests/test-cases/per-module-lib-deps/unwrapped-explicit-modules.t
index 1994c06f0a2..0514de0dace 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/unwrapped-explicit-modules.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/unwrapped-explicit-modules.t
@@ -1,11 +1,13 @@
-Regression baseline for the cctx-wide `.cmi` glob over an unwrapped
-library whose module set is declared explicitly via `(modules ...)`.
-Today, editing one sibling module's `.mli` invalidates every
-sibling's compile rule — even siblings that don't reference it.
+Per-module narrowing on a `(wrapped false)` library whose module
+set is declared explicitly via `(modules ...)`. Under the per-
+module narrowing, editing one sibling module's `.mli` invalidates
+only modules that reference it — siblings that don't are
+unaffected. Matches the implicit-discovery behaviour covered by
+`lib-to-lib-unwrapped.t`, but the explicit `(modules ...)` clause
+routes through a different parse path; this test pins the
+equivalence observationally.
 
-Matches the shape raised in #14492's review feedback. The explicit
-`(modules ...)` clause routes through a different parse path from
-the implicit form covered by `lib-to-lib-unwrapped.t`.
+Matches the shape raised in #14492's review feedback.
 
   $ make_dune_project 3.24
 
@@ -54,29 +56,28 @@ references `A` only; `uses_b` references `B` only.
 
   $ dune build @check
 
-Each consumer compile rule carries a wide `.cmi` glob over `foo`'s
-objdir; no specific cmi from `foo` appears as a file dep. The wide
-glob is the structural cause of the sibling over-rebuilds asserted
-below.
+Each consumer compile rule depends on only the specific cmi it
+references — `uses_a` on `a.cmi`, `uses_b` on `b.cmi` — with no
+wide glob over `foo`'s objdir.
 
   $ dune rules --root . --format=json --deps '%{cmo:consumer/uses_a}' > deps_a.json
   $ dune rules --root . --format=json --deps '%{cmo:consumer/uses_b}' > deps_b.json
   $ jq -r 'include "dune"; .[] | depsGlobs
   >   | select(.dir | endswith("foo/.foo.objs/byte"))
   >   | .dir + " " + .predicate' < deps_a.json
-  _build/default/foo/.foo.objs/byte *.cmi
   $ jq -r 'include "dune"; .[] | depsGlobs
   >   | select(.dir | endswith("foo/.foo.objs/byte"))
   >   | .dir + " " + .predicate' < deps_b.json
-  _build/default/foo/.foo.objs/byte *.cmi
   $ jq -r 'include "dune"; .[] | depsFilePaths
   >   | select(endswith("foo/.foo.objs/byte/a.cmi"))' < deps_a.json
+  _build/default/foo/.foo.objs/byte/a.cmi
   $ jq -r 'include "dune"; .[] | depsFilePaths
   >   | select(endswith("foo/.foo.objs/byte/b.cmi"))' < deps_b.json
+  _build/default/foo/.foo.objs/byte/b.cmi
 
 Case 1: edit `A`'s interface to expose `extra`. `uses_b` references
-only `B`, but the cctx-wide `.cmi` glob over `foo`'s objdir includes
-`A.cmi`, so today `uses_b.cm*` rebuilds anyway.
+only `B`, so the per-module narrowing must drop `A.cmi` from
+`uses_b`'s dep set — `uses_b.cm*` must not rebuild.
 
   $ cat > foo/a.mli <<EOF
   > val v : int
@@ -84,18 +85,10 @@ only `B`, but the cctx-wide `.cmi` glob over `foo`'s objdir includes
   > EOF
   $ dune build @check
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatching("uses_b.cm")]'
-  [
-    {
-      "target_files": [
-        "_build/default/consumer/.consumer.objs/byte/uses_b.cmi",
-        "_build/default/consumer/.consumer.objs/byte/uses_b.cmo",
-        "_build/default/consumer/.consumer.objs/byte/uses_b.cmt"
-      ]
-    }
-  ]
+  []
 
-Case 2: edit `B`'s interface to expose `extra`. Symmetric — today
-`uses_a.cm*` rebuilds anyway.
+Case 2: edit `B`'s interface to expose `extra`. Symmetric —
+`uses_a.cm*` must not rebuild.
 
   $ cat > foo/b.mli <<EOF
   > val v : int
@@ -103,12 +96,4 @@ Case 2: edit `B`'s interface to expose `extra`. Symmetric — today
   > EOF
   $ dune build @check
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatching("uses_a.cm")]'
-  [
-    {
-      "target_files": [
-        "_build/default/consumer/.consumer.objs/byte/uses_a.cmi",
-        "_build/default/consumer/.consumer.objs/byte/uses_a.cmo",
-        "_build/default/consumer/.consumer.objs/byte/uses_a.cmt"
-      ]
-    }
-  ]
+  []
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/unwrapped-tight-deps.t b/test/blackbox-tests/test-cases/per-module-lib-deps/unwrapped-tight-deps.t
index 449f2da858d..412b2af2d43 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/unwrapped-tight-deps.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/unwrapped-tight-deps.t
@@ -7,14 +7,13 @@ the dependency library [dep_lib] has its interface edited.
 [consumer] references only [Referenced_dep] from [dep_lib];
 [Unread_dep_a] and [Unread_dep_b] are present but unreferenced.
 
-On current main, editing any of the three rebuilds [consumer]
-because library-level dependency filtering (and, within that,
-per-module tightening) is not yet in place: the consumer is
-conservatively rebuilt whenever any entry module's cmi changes.
-Work on https://github.com/ocaml/dune/issues/4572 is expected to
-tighten this, at which point editing [Unread_dep_a] or
-[Unread_dep_b] leaves [consumer] untouched and the emitted target
-list becomes empty.
+The per-module filter restricts [consumer]'s deps to modules of
+[dep_lib] that [consumer]'s ocamldep output names — only
+[Referenced_dep]. Editing [Unread_dep_a] or [Unread_dep_b] thus
+leaves [consumer] untouched (empty target list); editing
+[Referenced_dep] still rebuilds it. Previously all three edits
+rebuilt [consumer] because the consumer was conservatively
+rebuilt whenever any entry module's cmi changed.
 
 See: https://github.com/ocaml/dune/issues/4572
 
@@ -84,15 +83,7 @@ reference — and record the rebuild targets for [consumer]:
   > EOF
   $ dune build @check
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("consumer_lib/\\.consumer_lib\\.objs/byte/consumer\\."))]'
-  [
-    {
-      "target_files": [
-        "_build/default/consumer_lib/.consumer_lib.objs/byte/consumer.cmi",
-        "_build/default/consumer_lib/.consumer_lib.objs/byte/consumer.cmo",
-        "_build/default/consumer_lib/.consumer_lib.objs/byte/consumer.cmt"
-      ]
-    }
-  ]
+  []
 
 Same for [Unread_dep_b]:
 
@@ -106,15 +97,7 @@ Same for [Unread_dep_b]:
   > EOF
   $ dune build @check
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("consumer_lib/\\.consumer_lib\\.objs/byte/consumer\\."))]'
-  [
-    {
-      "target_files": [
-        "_build/default/consumer_lib/.consumer_lib.objs/byte/consumer.cmi",
-        "_build/default/consumer_lib/.consumer_lib.objs/byte/consumer.cmo",
-        "_build/default/consumer_lib/.consumer_lib.objs/byte/consumer.cmt"
-      ]
-    }
-  ]
+  []
 
 Edit [Referenced_dep]'s interface — the one module [consumer] does
 reference — and record the rebuild targets ([consumer] must
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/unwrapped.t b/test/blackbox-tests/test-cases/per-module-lib-deps/unwrapped.t
index 908ce2e21b8..ea4aa1b697f 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/unwrapped.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/unwrapped.t
@@ -1,8 +1,6 @@
-Baseline: library dependency recompilation for unwrapped libraries.
-
-When an unwrapped library module's interface changes, Dune currently recompiles
-all modules in stanzas that depend on the library, even those referencing
-different modules in the library.
+Per-module filtering for unwrapped libraries: a consumer that references
+only some modules of an unwrapped library must not be recompiled when
+unreferenced modules in that library change.
 
 See: https://github.com/ocaml/dune/issues/4572
 
@@ -73,11 +71,11 @@ Change only helper.mli:
   > let new_helper s = s ^ "!"
   > EOF
 
-Uses_utils is recompiled even though it only references Utils, not Helper:
+Uses_utils references Utils only, not Helper, so it is not recompiled:
 
   $ dune build ./main.exe
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("Uses_utils"))] | length'
-  2
+  0
 
 Change only utils.mli:
 
@@ -90,8 +88,8 @@ Change only utils.mli:
   > let new_utils s = s ^ "?"
   > EOF
 
-Uses_helper is recompiled even though it only references Helper, not Utils:
+Uses_helper references Helper only, not Utils, so it is not recompiled:
 
   $ dune build ./main.exe
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("Uses_helper"))] | length'
-  2
+  0
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/wrapped-compat.t b/test/blackbox-tests/test-cases/per-module-lib-deps/wrapped-compat.t
index adc34c6f62b..92fd82b0636 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/wrapped-compat.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/wrapped-compat.t
@@ -67,8 +67,8 @@ See: https://github.com/ocaml/dune/issues/4572
   > let new_fn () = "hello"
   > EOF
 
-Standalone is recompiled even though it doesn't reference Baselib:
+Standalone is not recompiled because it doesn't reference Baselib:
 
   $ dune build ./main.exe
   $ dune trace cat | jq -s 'include "dune"; [.[] | targetsMatchingFilter(test("Standalone"))] | length'
-  2
+  0
diff --git a/test/blackbox-tests/test-cases/per-module-lib-deps/wrapped-internal-leak.t b/test/blackbox-tests/test-cases/per-module-lib-deps/wrapped-internal-leak.t
index 4b781bb4f5b..4f8e515b320 100644
--- a/test/blackbox-tests/test-cases/per-module-lib-deps/wrapped-internal-leak.t
+++ b/test/blackbox-tests/test-cases/per-module-lib-deps/wrapped-internal-leak.t
@@ -1,30 +1,28 @@
-Observational baseline for an unsupported leak: a consumer can
-currently reach a wrapped library's internal (mangled) module name
-through the include path, because the library's object directory
-contains the mangled `Mylib__Internal.cmi` and broad `-I` flags make
-that directory reachable.
+A consumer that writes `Mylib__Internal.x` — using a wrapped
+library's mangled internal module name directly, bypassing the
+wrapper — no longer compiles. This file asserts the compile
+error.
 
-A wrapped library exposes its public API only through its wrapper
-module (`Mylib.Internal`, etc). Dune mangles the on-disk cmi of the
-wrapped internal module to `Mylib__Internal.cmi` as an implementation
-detail. Under broad per-module `-I` flags, a consumer that writes
-`Mylib__Internal.x` compiles successfully, side-stepping the wrapper.
+Why it fails: per-module rule-dep filtering (#4572)
+scopes each consumer's compile-rule deps to the libraries its
+source actually references. The consumer's ocamldep output
+names `Mylib__Internal` as a top-level module, but
+`Mylib__Internal` is not a library entry — the lib index only
+knows about `Mylib`. The filter therefore does not list
+`Mylib__Internal.cmi` among the consumer's compile-rule deps;
+dune does not order the producing rule before the consumer's
+compile, and ocamlc reports `Unbound module` because the file
+is absent from `mylib`'s objdir when the consumer's compile
+runs.
 
-This is not officially supported — consumers should reach a wrapped
-library's internals only through the wrapper API, not through the
-mangled form (see #14317 review discussion). The leak works today
-only as an implementation-detail side effect of the wrapping
-convention. In practice some packages currently depend on it, which
-is why the baseline is recorded here so any flip is visible in CI.
-
-Per-module `-I` filtering (#4572 / #14186) is expected to break this
-leak by scoping each consumer's `-I` paths to the libraries its
-source references. `Mylib__Internal` is not an entry in the lib
-index, so the filter excludes `mylib`, the objdir is dropped from
-`-I`, and the compile fails with "Unbound module Mylib__Internal".
-The flip is acceptable because the leak was never supported;
-downstream consumers depending on the mangled form should migrate
-to the wrapper API.
+Why this isn't a regression: the mangled form was never
+officially supported. Wrapped libraries expose their public API
+through the wrapper module (`Mylib.Internal.x`); the on-disk
+mangling to `Mylib__Internal.cmi` is an implementation detail.
+Under broad cctx-wide compile-rule deps the leak previously
+compiled by accident; per-module rule-dep filtering removes the
+accidental reachability. Downstream consumers depending on the
+mangled form should migrate to the wrapper API.
 
   $ cat > dune-project <<EOF
   > (lang dune 3.0)
@@ -49,3 +47,8 @@ to the wrapper API.
   > EOF
 
   $ dune build ./main.exe
+  File "main.ml", line 1, characters 23-38:
+  1 | let () = print_endline Mylib__Internal.hi
+                             ^^^^^^^^^^^^^^^
+  Error: Unbound module Mylib__Internal
+  [1]
diff --git a/test/blackbox-tests/test-cases/reporting-of-cycles.t/a/a1/x.ml b/test/blackbox-tests/test-cases/reporting-of-cycles.t/a/a1/x.ml
index e69de29bb2d..941c54ea28c 100644
--- a/test/blackbox-tests/test-cases/reporting-of-cycles.t/a/a1/x.ml
+++ b/test/blackbox-tests/test-cases/reporting-of-cycles.t/a/a1/x.ml
@@ -0,0 +1 @@
+let value = B.X.value
diff --git a/test/blackbox-tests/test-cases/reporting-of-cycles.t/a/a2/x.ml b/test/blackbox-tests/test-cases/reporting-of-cycles.t/a/a2/x.ml
index e69de29bb2d..1b906314f93 100644
--- a/test/blackbox-tests/test-cases/reporting-of-cycles.t/a/a2/x.ml
+++ b/test/blackbox-tests/test-cases/reporting-of-cycles.t/a/a2/x.ml
@@ -0,0 +1 @@
+let value = 0
diff --git a/test/blackbox-tests/test-cases/reporting-of-cycles.t/b/x.ml b/test/blackbox-tests/test-cases/reporting-of-cycles.t/b/x.ml
index e69de29bb2d..4ca1eb86d04 100644
--- a/test/blackbox-tests/test-cases/reporting-of-cycles.t/b/x.ml
+++ b/test/blackbox-tests/test-cases/reporting-of-cycles.t/b/x.ml
@@ -0,0 +1 @@
+let value = A2.X.value
diff --git a/test/blackbox-tests/test-cases/strict-package-deps.t b/test/blackbox-tests/test-cases/strict-package-deps.t
index 2f724b4f08e..abc2a1ecea9 100644
--- a/test/blackbox-tests/test-cases/strict-package-deps.t
+++ b/test/blackbox-tests/test-cases/strict-package-deps.t
@@ -8,8 +8,8 @@ the package dependencies inferred by dune:
   > (package (name foo))
   > EOF
   $ mkdir foo bar
-  $ touch foo/foo.ml
-  $ touch bar/bar.ml
+  $ echo 'let () = print_int Bar.value' >foo/foo.ml
+  $ echo 'let value = 1' >bar/bar.ml
   $ cat >foo/dune <<EOF
   > (executable (public_name foo) (libraries bar) (package foo))
   > EOF
@@ -26,6 +26,9 @@ the package dependencies inferred by dune:
   $ cat >foo/dune <<EOF
   > (library (public_name foo) (libraries bar))
   > EOF
+  $ cat >foo/foo.ml <<EOF
+  > let use_bar () = Bar.value
+  > EOF
   $ dune build @install
   Error: Package foo is missing the following package dependencies
   - bar
@@ -45,7 +48,9 @@ transitive deps.
   > (package (name bar) (depends baz))
   > (package (name foo) (depends bar))
   > EOF
-  $ touch baz.ml bar.ml foo.ml
+  $ echo 'let value = 1' >baz.ml
+  $ echo 'let chain = Baz.value' >bar.ml
+  $ echo 'let use = Bar.chain' >foo.ml
   $ cat >dune <<EOF
   > (library (public_name baz) (modules baz))
   > (library (public_name bar) (libraries baz) (modules bar))
diff --git a/test/blackbox-tests/test-cases/watching/multiple-errors-output.t/run.t b/test/blackbox-tests/test-cases/watching/multiple-errors-output.t/run.t
index 79458d994fb..97fd398c369 100644
--- a/test/blackbox-tests/test-cases/watching/multiple-errors-output.t/run.t
+++ b/test/blackbox-tests/test-cases/watching/multiple-errors-output.t/run.t
@@ -15,10 +15,18 @@ We test the output of the watch mode client when we have multiple errors
   1 | let y = "unknown variable" ^ what
                                    ^^^^
   Unbound value what
-  Error: Build failed with 2 errors.
+  File "$TESTCASE_ROOT/src/foo.ml", line 1, characters 39-40:
+  1 | let f = Bar.x + Baz.y + invalid_syntax : ? = !
+                                             ^
+  Syntax error
+  Error: Build failed with 3 errors.
   [1]
 
   $ stop_dune
+  File "src/foo.ml", line 1, characters 39-40:
+  1 | let f = Bar.x + Baz.y + invalid_syntax : ? = !
+                                             ^
+  Error: Syntax error
   File "libs/bar.ml", line 1, characters 8-20:
   1 | let y = "type error" + 3
               ^^^^^^^^^^^^
@@ -28,4 +36,4 @@ We test the output of the watch mode client when we have multiple errors
   1 | let y = "unknown variable" ^ what
                                    ^^^^
   Error: Unbound value what
-  Had 2 errors, waiting for filesystem changes...
+  Had 3 errors, waiting for filesystem changes...