diff --git a/.github/workflows/Process-PSModule.yml b/.github/workflows/Process-PSModule.yml
index 0aee102..9c157c3 100644
--- a/.github/workflows/Process-PSModule.yml
+++ b/.github/workflows/Process-PSModule.yml
@@ -27,15 +27,14 @@ permissions:
 
 jobs:
   Process-PSModule:
-    uses: PSModule/Process-PSModule/.github/workflows/workflow.yml@d4020f3c9c3621cebae5d8bf4ffaf10f55c1784a # v6.1.2
+    # SPIKE: pinned to the Process-PSModule branch that adds the 'Environment' input.
+    # MariusStorhaug (personal) -> PSModule (org) is CROSS-OWNER, and `secrets: inherit`
+    # only works within the same org/enterprise, so we must pass APIKey explicitly. That
+    # closes the secrets context, so environment SECRETS cannot flow here (same-org
+    # consumers using secrets: inherit do get them). Environment VARIABLES still flow via
+    # the vars context once the test jobs bind to the environment.
+    uses: PSModule/Process-PSModule/.github/workflows/workflow.yml@spike/environment-support
     secrets:
       APIKey: ${{ secrets.APIKey }}
-      TestData: >-
-        {
-          "secrets": {
-            "TEST_SECRET": "${{ secrets.TEST_SECRET }}"
-          },
-          "variables": {
-            "TEST_VARIABLE": "${{ vars.TEST_VARIABLE }}"
-          }
-        }
+    with:
+      Environment: Testing
diff --git a/.github/workflows/env-probe-mid.yml b/.github/workflows/env-probe-mid.yml
new file mode 100644
index 0000000..78a94bb
--- /dev/null
+++ b/.github/workflows/env-probe-mid.yml
@@ -0,0 +1,16 @@
+name: env-probe-mid
+
+# SPIKE probe: intermediate reusable workflow that does NOT bind an environment; it
+# only forwards secrets down with `secrets: inherit`. Mirrors Process-PSModule's
+# workflow.yml sitting between the caller and the environment-bound leaf job.
+
+on:
+  workflow_call:
+
+permissions:
+  contents: read
+
+jobs:
+  mid:
+    uses: ./.github/workflows/env-probe-reusable.yml
+    secrets: inherit
diff --git a/.github/workflows/env-probe-reusable.yml b/.github/workflows/env-probe-reusable.yml
new file mode 100644
index 0000000..0b9641a
--- /dev/null
+++ b/.github/workflows/env-probe-reusable.yml
@@ -0,0 +1,35 @@
+name: env-probe-reusable
+
+# SPIKE probe: a reusable workflow whose job binds to the `Testing` environment.
+# Determines whether an environment SECRET is reachable inside a reusable workflow,
+# both by enumeration (toJSON(secrets)) and by explicit declared name.
+
+on:
+  workflow_call:
+    secrets:
+      TEST_ENV_SECRET:
+        description: Declared so it can be referenced by name; the environment value should override.
+        required: false
+
+permissions:
+  contents: read
+
+jobs:
+  reusable-probe:
+    runs-on: ubuntu-latest
+    environment: Testing
+    steps:
+      - name: Probe contexts inside a reusable workflow bound to the environment
+        shell: pwsh
+        env:
+          ALL_SECRETS: ${{ toJSON(secrets) }}
+          ALL_VARS: ${{ toJSON(vars) }}
+          NAMED_DECLARED_SECRET: ${{ secrets.TEST_ENV_SECRET }}
+          NAMED_ENV_VAR: ${{ vars.TEST_ENV_VARIABLE }}
+        run: |
+          $s = $env:ALL_SECRETS | ConvertFrom-Json
+          $v = $env:ALL_VARS | ConvertFrom-Json
+          Write-Host "REUSABLE secrets keys: $((@($s.PSObject.Properties.Name) | Sort-Object) -join ', ')"
+          Write-Host "REUSABLE vars keys:    $((@($v.PSObject.Properties.Name) | Sort-Object) -join ', ')"
+          Write-Host "REUSABLE named declared secret (TEST_ENV_SECRET) present: $(-not [string]::IsNullOrEmpty($env:NAMED_DECLARED_SECRET))"
+          Write-Host "REUSABLE named env var (TEST_ENV_VARIABLE) present:       $(-not [string]::IsNullOrEmpty($env:NAMED_ENV_VAR))"
diff --git a/.github/workflows/env-probe.yml b/.github/workflows/env-probe.yml
new file mode 100644
index 0000000..a29319a
--- /dev/null
+++ b/.github/workflows/env-probe.yml
@@ -0,0 +1,53 @@
+name: env-probe
+
+# SPIKE probe: compares how an environment's secret/variable are seen by a DIRECT
+# job vs a REUSABLE workflow job, both bound to the `Testing` environment.
+# Runs on push to the spike branch (workflow_dispatch needs the file on the default branch).
+
+on:
+  push:
+    branches:
+      - spike/environment-testdata
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  # Baseline: a normal (non-reusable) job binds to an environment directly.
+  direct-probe:
+    runs-on: ubuntu-latest
+    environment: Testing
+    steps:
+      - name: Probe contexts in a direct job bound to the environment
+        shell: pwsh
+        env:
+          ALL_SECRETS: ${{ toJSON(secrets) }}
+          ALL_VARS: ${{ toJSON(vars) }}
+          NAMED_SECRET: ${{ secrets.TEST_ENV_SECRET }}
+          NAMED_VAR: ${{ vars.TEST_ENV_VARIABLE }}
+        run: |
+          $s = $env:ALL_SECRETS | ConvertFrom-Json
+          $v = $env:ALL_VARS | ConvertFrom-Json
+          Write-Host "DIRECT secrets keys: $((@($s.PSObject.Properties.Name) | Sort-Object) -join ', ')"
+          Write-Host "DIRECT vars keys:    $((@($v.PSObject.Properties.Name) | Sort-Object) -join ', ')"
+          Write-Host "DIRECT named env secret present: $(-not [string]::IsNullOrEmpty($env:NAMED_SECRET))"
+          Write-Host "DIRECT named env var present:    $(-not [string]::IsNullOrEmpty($env:NAMED_VAR))"
+
+  # The real question: does a reusable workflow bound to the environment get the env
+  # secret WITHOUT the caller passing it (the caller cannot, being a `uses:` job)?
+  reusable-no-pass:
+    uses: ./.github/workflows/env-probe-reusable.yml
+    # deliberately passes nothing
+
+  # Does secrets: inherit change anything? (The caller job cannot bind to an
+  # environment, so inherited secrets should NOT include the environment secret.)
+  reusable-inherit:
+    uses: ./.github/workflows/env-probe-reusable.yml
+    secrets: inherit
+
+  # 3-level nested chain mirroring Process-PSModule (caller -> workflow.yml ->
+  # Test-ModuleLocal): inherit at every hop, environment bound only on the leaf.
+  reusable-3level:
+    uses: ./.github/workflows/env-probe-mid.yml
+    secrets: inherit
diff --git a/src/functions/public/Get-PSModuleTest.ps1 b/src/functions/public/Get-PSModuleTest.ps1
index fe4d4cc..78451b3 100644
--- a/src/functions/public/Get-PSModuleTest.ps1
+++ b/src/functions/public/Get-PSModuleTest.ps1
@@ -22,5 +22,7 @@
         [Parameter(Mandatory)]
         [string] $Name
     )
+    # SPIKE: touched so the change matches the ^src/ important-file pattern and the
+    # module build + local test jobs run for this pull request.
     Write-Output "Hello, $Name!"
 }
diff --git a/tests/Environment.Tests.ps1 b/tests/Environment.Tests.ps1
index 3b90a6b..164d8ab 100644
--- a/tests/Environment.Tests.ps1
+++ b/tests/Environment.Tests.ps1
@@ -13,21 +13,29 @@
 [CmdletBinding()]
 param()
 
-Describe 'TestData is pushed into the module tests' {
-    It 'Exposes the secret from the "secrets" map' {
-        $actual = [System.Environment]::GetEnvironmentVariable('TEST_SECRET')
+Describe 'Environment-scoped test data reaches the module tests' {
+    # This module is called CROSS-OWNER (MariusStorhaug personal account -> PSModule org).
+    # GitHub only allows `secrets: inherit` within the same org/enterprise, so environment
+    # SECRETS cannot flow to a cross-owner consumer. Environment VARIABLES flow regardless,
+    # via the vars context, once the reusable workflow binds the test job to the environment.
+    # TEST_ENV_VARIABLE exists ONLY in the "Testing" environment (not at repo level), so
+    # seeing it here proves it was sourced from the environment.
+    It 'Exposes the environment variable as $env:TEST_ENV_VARIABLE' {
+        $actual = [System.Environment]::GetEnvironmentVariable('TEST_ENV_VARIABLE')
         $actual | Should -Not -BeNullOrEmpty
-        $actual | Should -BeExactly 'mariustestmodule-secret-fixture-value'
+        $actual | Should -BeExactly 'env-scoped-variable-fixture-value'
     }
 
-    It 'Exposes the variable from the "variables" map' {
-        $actual = [System.Environment]::GetEnvironmentVariable('TEST_VARIABLE')
-        $actual | Should -Not -BeNullOrEmpty
-        $actual | Should -BeExactly 'mariustestmodule-variable-fixture-value'
+    # Environment secrets require `secrets: inherit` end-to-end, which is unavailable
+    # cross-owner. A SAME-ORG consumer would drop the -Skip and this would pass (proven by
+    # the env-probe* workflows in this repo, which show the secret reaching a reusable
+    # workflow that is called with secrets: inherit and bound to the environment).
+    It 'Exposes the environment secret as $env:TEST_ENV_SECRET (same-org callers only)' -Skip {
+        $actual = [System.Environment]::GetEnvironmentVariable('TEST_ENV_SECRET')
+        $actual | Should -BeExactly 'env-scoped-secret-fixture-value'
     }
 
-    It 'Masks the secret in the log even when a test prints it in plain text' {
-        Write-Host "Secret in plain text:   $env:TEST_SECRET"
-        Write-Host "Variable in plain text: $env:TEST_VARIABLE"
+    It 'Shows the environment variable in the log' {
+        Write-Host "Variable in plain text: $env:TEST_ENV_VARIABLE"
     }
 }