diff --git a/tests/test_csp_nonce_unsafe_inline_contract.py b/tests/test_csp_nonce_unsafe_inline_contract.py
new file mode 100644
index 00000000..080abedb
--- /dev/null
+++ b/tests/test_csp_nonce_unsafe_inline_contract.py
@@ -0,0 +1,80 @@
+# Copyright (c) 2026 Code Infinity
+# SPDX-License-Identifier: MPL-2.0
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+"""CSP nonce respects a user's 'unsafe-inline' (ADR-0100, refines ADR-0088).
+
+A browser ignores 'unsafe-inline' in any directive that also lists a nonce
+(CSP Level 2+). Since 3.13.143 the framework appended its per-response nonce to
+script-src/style-src unconditionally - including an app's own TINA4_CSP - so an
+app that deliberately allowed inline through 'unsafe-inline' had it silently
+blocked (tina4-php#330). The rule now: a directive (present, or derived from
+default-src) that already carries 'unsafe-inline' gets NO nonce; the app's
+explicit choice wins. The strict default policy is unchanged and still nonced.
+
+The answer key is tina4-documentation/plan/v3/fixtures/securityheaders_contract.json,
+invariant csp-nonce-respects-unsafe-inline. The same cases run in all four
+frameworks on the real inject function - no mocks, a pure string transform.
+"""
+from tina4_python.core.csp import inject_nonce_into_csp
+
+NONCE = "abc123"
+TOKEN = "'nonce-abc123'"
+
+
+def _directive(csp: str, name: str) -> str:
+    for part in csp.split(";"):
+        part = part.strip()
+        if part.split(" ", 1)[0].lower() == name:
+            return part
+    return ""
+
+
+def test_explicit_unsafe_inline_script_src_keeps_unsafe_inline_and_gets_no_nonce():
+    out = inject_nonce_into_csp(
+        "default-src 'self'; script-src 'self' 'unsafe-inline'", NONCE
+    )
+    assert "'unsafe-inline'" in _directive(out, "script-src")
+    assert TOKEN not in _directive(out, "script-src")
+
+
+def test_explicit_unsafe_inline_style_src_keeps_unsafe_inline_and_gets_no_nonce():
+    out = inject_nonce_into_csp(
+        "default-src 'self'; style-src 'self' 'unsafe-inline'", NONCE
+    )
+    assert "'unsafe-inline'" in _directive(out, "style-src")
+    assert TOKEN not in _directive(out, "style-src")
+
+
+def test_unsafe_inline_default_src_does_not_spawn_a_nonced_directive():
+    out = inject_nonce_into_csp("default-src 'self' 'unsafe-inline'", NONCE)
+    # No derived script-src/style-src is added - they fall back to default-src,
+    # so the app's inline keeps working; the nonce is nowhere.
+    assert TOKEN not in out
+    assert _directive(out, "script-src") == ""
+    assert _directive(out, "style-src") == ""
+
+
+def test_mixed_unsafe_inline_script_but_strict_style_nonces_only_style():
+    out = inject_nonce_into_csp(
+        "default-src 'self'; script-src 'self' 'unsafe-inline'", NONCE
+    )
+    # script-src opted into inline -> untouched; style-src derived from the
+    # strict default -> gets the nonce so framework inline styles still run.
+    assert TOKEN not in _directive(out, "script-src")
+    assert TOKEN in _directive(out, "style-src")
+
+
+def test_strict_default_policy_still_gets_the_nonce():
+    out = inject_nonce_into_csp("default-src 'self'", NONCE)
+    assert TOKEN in _directive(out, "script-src")
+    assert TOKEN in _directive(out, "style-src")
+
+
+def test_explicit_non_unsafe_inline_directive_still_gets_the_nonce():
+    out = inject_nonce_into_csp(
+        "default-src 'self'; script-src 'self' https://cdn.example", NONCE
+    )
+    assert TOKEN in _directive(out, "script-src")
diff --git a/tina4_python/core/csp.py b/tina4_python/core/csp.py
index cb63c31f..1ba2900c 100644
--- a/tina4_python/core/csp.py
+++ b/tina4_python/core/csp.py
@@ -100,10 +100,23 @@ def inject_nonce_into_csp(csp: str, nonce: str) -> str:
     for directive in ("style-src", "script-src"):
         existing = next((d for d in directives if d[0] == directive), None)
         if existing is not None:
+            # ADR-0100: the app opted this directive into inline via
+            # 'unsafe-inline'. A browser ignores 'unsafe-inline' the moment a
+            # nonce joins the same directive (CSP Level 2+), so adding the nonce
+            # would silently block the inline the app asked for. The app's
+            # explicit choice wins; its own inline runs, framework inline rides
+            # the same 'unsafe-inline'.
+            if "'unsafe-inline'" in existing[1].split():
+                continue
             if token not in existing[1].split():
                 existing[1] = (existing[1] + " " + token).strip()
         else:
             base = default_value if default_value else "'self'"
+            # ADR-0100: a directive derived from an 'unsafe-inline' default-src
+            # must not be spawned with a nonce - it would cancel the inline the
+            # app allowed through default-src. Leave it to fall back.
+            if "'unsafe-inline'" in base.split():
+                continue
             directives.append([directive, (base + " " + token).strip()])
 
     return "; ".join(