diff --git a/.importlinter b/.importlinter
new file mode 100644
index 000000000..107b08d3e
--- /dev/null
+++ b/.importlinter
@@ -0,0 +1,41 @@
+[importlinter]
+root_package = cleveragents
+include_external_packages = True
+
+[importlinter:contract:cli-no-application-direct]
+name = CLI must not import Application services directly
+type = forbidden
+source_modules =
+    cleveragents.cli
+forbidden_modules =
+    cleveragents.application.services
+ignore_imports =
+    cleveragents.cli.commands.plan -> cleveragents.application.services.plan_apply_service
+    cleveragents.cli.commands.plan -> cleveragents.application.services.plan_lifecycle_service
+    cleveragents.cli.commands.plan -> cleveragents.application.services.plan_service
+    cleveragents.cli.commands.plan -> cleveragents.application.services.project_service
+    cleveragents.cli.commands.plan -> cleveragents.application.services.execute_phase_context_assembler
+    cleveragents.cli.commands.plan -> cleveragents.application.services.llm_actors
+    cleveragents.cli.commands.plan -> cleveragents.application.services.plan_executor
+    cleveragents.cli.commands.plan -> cleveragents.application.services.strategy_actor
+    cleveragents.cli.commands.plan -> cleveragents.application.services.plan_preflight_guardrail
+    cleveragents.cli.commands.plan -> cleveragents.application.services.plan_resume_service
+    cleveragents.cli.commands.plan -> cleveragents.application.services.decision_service
+    cleveragents.cli.commands.plan -> cleveragents.application.container
+    cleveragents.cli.commands.context -> cleveragents.application.services.context_service
+    cleveragents.cli.commands.context -> cleveragents.application.services.project_service
+    cleveragents.cli.commands.context -> cleveragents.application.container
+    cleveragents.cli.commands.resource -> cleveragents.application.services.resource_registry_service
+    cleveragents.cli.commands.resource -> cleveragents.application.container
+    cleveragents.cli.commands.skill -> cleveragents.application.services.skill_service
+    cleveragents.cli.commands.skill -> cleveragents.application.services.config_service
+    cleveragents.cli.commands.skill -> cleveragents.application.container
+    cleveragents.cli.commands.invariant -> cleveragents.application.services.invariant_service
+
+[importlinter:contract:application-no-presentation]
+name = Application layer must not import from Presentation (CLI) layer
+type = forbidden
+source_modules =
+    cleveragents.application
+forbidden_modules =
+    cleveragents.cli
diff --git a/features/a2a_boundary_enforcement.feature b/features/a2a_boundary_enforcement.feature
new file mode 100644
index 000000000..5199e12eb
--- /dev/null
+++ b/features/a2a_boundary_enforcement.feature
@@ -0,0 +1,59 @@
+Feature: A2A architectural boundary enforcement
+  As a developer
+  I want to verify that the CLI layer does not bypass the A2A boundary
+  So that the architecture remains clean and maintainable
+
+  Background:
+    Given the source directory exists at "src/cleveragents"
+
+  Scenario: Application layer does not import from CLI (Presentation) layer
+    Given the application services directory exists
+    When I scan all application service modules for CLI imports
+    Then no application service module should import from "cleveragents.cli"
+
+  Scenario: plan_apply_service uses shared output_format instead of CLI formatting
+    Given the plan_apply_service module exists
+    When I inspect plan_apply_service imports
+    Then it should not import from "cleveragents.cli.formatting"
+    And it should import from "cleveragents.shared.output_format"
+
+  Scenario: shared output_format module has no CLI dependencies
+    Given the shared output_format module exists
+    When I inspect shared output_format imports
+    Then it should not import from "cleveragents.cli"
+
+  Scenario: format_data function handles JSON format
+    Given the shared output_format module is imported
+    When I call format_data with a dict and format "json"
+    Then the result should be valid JSON
+    And the result should contain the expected keys
+
+  Scenario: format_data function handles YAML format
+    Given the shared output_format module is imported
+    When I call format_data with a dict and format "yaml"
+    Then the result should be valid YAML
+
+  Scenario: format_data function handles plain format
+    Given the shared output_format module is imported
+    When I call format_data with a dict and format "plain"
+    Then the result should contain key-value pairs
+
+  Scenario: format_data function handles table format
+    Given the shared output_format module is imported
+    When I call format_data with a list of dicts and format "table"
+    Then the result should contain column headers
+
+  Scenario: format_data function falls back to JSON for unknown format
+    Given the shared output_format module is imported
+    When I call format_data with a dict and format "unknown"
+    Then the result should be valid JSON
+
+  Scenario: format_data handles empty list for table format
+    Given the shared output_format module is imported
+    When I call format_data with an empty list and format "table"
+    Then the result should be "(empty)"
+
+  Scenario: format_data handles nested dict values
+    Given the shared output_format module is imported
+    When I call format_data with a nested dict and format "plain"
+    Then the result should contain nested key-value pairs
diff --git a/features/steps/a2a_boundary_enforcement_steps.py b/features/steps/a2a_boundary_enforcement_steps.py
new file mode 100644
index 000000000..aa7a447b9
--- /dev/null
+++ b/features/steps/a2a_boundary_enforcement_steps.py
@@ -0,0 +1,283 @@
+"""Step definitions for A2A architectural boundary enforcement tests."""
+
+from __future__ import annotations
+
+import ast
+import json
+from pathlib import Path
+from typing import Any
+
+import yaml
+from behave import given, then, when
+
+
+@given("the application services directory exists")
+def step_application_services_dir_exists(context: Any) -> None:
+    """Verify the application services directory exists."""
+    context.app_services_dir = Path("src/cleveragents/application/services")
+    assert context.app_services_dir.exists(), (
+        f"Application services directory not found: {context.app_services_dir}"
+    )
+
+
+@when("I scan all application service modules for CLI imports")
+def step_scan_application_services_for_cli_imports(context: Any) -> None:
+    """Scan all application service modules for CLI imports."""
+    context.cli_violations: list[str] = []
+    for py_file in context.app_services_dir.rglob("*.py"):
+        try:
+            tree = ast.parse(py_file.read_text())
+        except SyntaxError:
+            continue
+        for node in ast.walk(tree):
+            if isinstance(node, ast.ImportFrom) and node.module:
+                if node.module.startswith("cleveragents.cli"):
+                    context.cli_violations.append(
+                        f"{py_file}:{node.lineno}: "
+                        f"from {node.module} import ..."
+                    )
+            elif isinstance(node, ast.Import):
+                for alias in node.names:
+                    if alias.name.startswith("cleveragents.cli"):
+                        context.cli_violations.append(
+                            f"{py_file}:{node.lineno}: "
+                            f"import {alias.name}"
+                        )
+
+
+@then('no application service module should import from "cleveragents.cli"')
+def step_no_cli_imports_in_application(context: Any) -> None:
+    """Assert no application service imports from CLI layer."""
+    violations = getattr(context, "cli_violations", [])
+    assert not violations, (
+        "Application services must not import from CLI (Presentation) layer.\n"
+        "Violations found:\n" + "\n".join(violations)
+    )
+
+
+@given("the plan_apply_service module exists")
+def step_plan_apply_service_exists(context: Any) -> None:
+    """Verify plan_apply_service.py exists."""
+    context.plan_apply_service_path = Path(
+        "src/cleveragents/application/services/plan_apply_service.py"
+    )
+    assert context.plan_apply_service_path.exists(), (
+        "plan_apply_service.py not found"
+    )
+
+
+@when("I inspect plan_apply_service imports")
+def step_inspect_plan_apply_service_imports(context: Any) -> None:
+    """Parse imports from plan_apply_service.py."""
+    content = context.plan_apply_service_path.read_text()
+    context.plan_apply_service_content = content
+    try:
+        tree = ast.parse(content)
+    except SyntaxError as exc:
+        raise AssertionError(
+            f"Syntax error in plan_apply_service.py: {exc}"
+        ) from exc
+    context.plan_apply_imports: list[str] = []
+    for node in ast.walk(tree):
+        if isinstance(node, ast.ImportFrom) and node.module:
+            context.plan_apply_imports.append(node.module)
+        elif isinstance(node, ast.Import):
+            for alias in node.names:
+                context.plan_apply_imports.append(alias.name)
+
+
+@then('it should not import from "cleveragents.cli.formatting"')
+def step_plan_apply_service_no_cli_formatting(context: Any) -> None:
+    """Assert plan_apply_service does not import from cli.formatting."""
+    imports = getattr(context, "plan_apply_imports", [])
+    cli_formatting_imports = [
+        imp for imp in imports if imp == "cleveragents.cli.formatting"
+    ]
+    assert not cli_formatting_imports, (
+        "plan_apply_service.py must not import from cleveragents.cli.formatting. "
+        "Use cleveragents.shared.output_format instead."
+    )
+
+
+@then('it should import from "cleveragents.shared.output_format"')
+def step_plan_apply_service_uses_shared_output(context: Any) -> None:
+    """Assert plan_apply_service imports from shared.output_format."""
+    content = getattr(context, "plan_apply_service_content", "")
+    assert "cleveragents.shared.output_format" in content, (
+        "plan_apply_service.py should import from "
+        "cleveragents.shared.output_format for output formatting."
+    )
+
+
+@given("the shared output_format module exists")
+def step_shared_output_format_exists(context: Any) -> None:
+    """Verify shared/output_format.py exists."""
+    context.output_format_path = Path(
+        "src/cleveragents/shared/output_format.py"
+    )
+    assert context.output_format_path.exists(), (
+        "shared/output_format.py not found"
+    )
+
+
+@when("I inspect shared output_format imports")
+def step_inspect_shared_output_format_imports(context: Any) -> None:
+    """Parse imports from shared/output_format.py."""
+    content = context.output_format_path.read_text()
+    try:
+        tree = ast.parse(content)
+    except SyntaxError as exc:
+        raise AssertionError(
+            f"Syntax error in shared/output_format.py: {exc}"
+        ) from exc
+    context.output_format_imports: list[str] = []
+    for node in ast.walk(tree):
+        if isinstance(node, ast.ImportFrom) and node.module:
+            context.output_format_imports.append(node.module)
+        elif isinstance(node, ast.Import):
+            for alias in node.names:
+                context.output_format_imports.append(alias.name)
+
+
+@then('it should not import from "cleveragents.cli"')
+def step_shared_output_format_no_cli_imports(context: Any) -> None:
+    """Assert shared/output_format.py has no CLI imports."""
+    imports = getattr(context, "output_format_imports", [])
+    cli_imports = [imp for imp in imports if imp.startswith("cleveragents.cli")]
+    assert not cli_imports, (
+        "shared/output_format.py must not import from cleveragents.cli. "
+        f"Found: {cli_imports}"
+    )
+
+
+@given("the shared output_format module is imported")
+def step_import_shared_output_format(context: Any) -> None:
+    """Import the shared output_format module."""
+    from cleveragents.shared.output_format import format_data
+
+    context.format_data = format_data
+
+
+@when('I call format_data with a dict and format "json"')
+def step_call_format_data_json(context: Any) -> None:
+    """Call format_data with JSON format."""
+    context.sample_data: dict[str, Any] = {
+        "plan_id": "01HXYZ",
+        "status": "applied",
+        "count": 42,
+    }
+    context.format_result = context.format_data(context.sample_data, "json")
+
+
+@when('I call format_data with a dict and format "yaml"')
+def step_call_format_data_yaml(context: Any) -> None:
+    """Call format_data with YAML format."""
+    context.sample_data = {"plan_id": "01HXYZ", "status": "applied", "count": 42}
+    context.format_result = context.format_data(context.sample_data, "yaml")
+
+
+@when('I call format_data with a dict and format "plain"')
+def step_call_format_data_plain(context: Any) -> None:
+    """Call format_data with plain format."""
+    context.sample_data = {"plan_id": "01HXYZ", "status": "applied", "count": 42}
+    context.format_result = context.format_data(context.sample_data, "plain")
+
+
+@when('I call format_data with a list of dicts and format "table"')
+def step_call_format_data_table(context: Any) -> None:
+    """Call format_data with table format."""
+    context.sample_data = [
+        {"plan_id": "01HXYZ", "status": "applied"},
+        {"plan_id": "01HABC", "status": "pending"},
+    ]
+    context.format_result = context.format_data(context.sample_data, "table")
+
+
+@when('I call format_data with a dict and format "unknown"')
+def step_call_format_data_unknown(context: Any) -> None:
+    """Call format_data with unknown format (should fall back to JSON)."""
+    context.sample_data = {"plan_id": "01HXYZ", "status": "applied"}
+    context.format_result = context.format_data(context.sample_data, "unknown")
+
+
+@when('I call format_data with an empty list and format "table"')
+def step_call_format_data_empty_table(context: Any) -> None:
+    """Call format_data with empty list and table format."""
+    context.format_result = context.format_data([], "table")
+
+
+@when('I call format_data with a nested dict and format "plain"')
+def step_call_format_data_nested_plain(context: Any) -> None:
+    """Call format_data with nested dict and plain format."""
+    context.sample_data = {
+        "plan_id": "01HXYZ",
+        "metadata": {"author": "test", "version": "1.0"},
+    }
+    context.format_result = context.format_data(context.sample_data, "plain")
+
+
+@then("the result should be valid JSON")
+def step_result_is_valid_json(context: Any) -> None:
+    """Assert the result is valid JSON."""
+    result = context.format_result
+    assert isinstance(result, str), f"Expected str, got {type(result)}"
+    try:
+        json.loads(result)
+    except json.JSONDecodeError as exc:
+        raise AssertionError(
+            f"Result is not valid JSON: {exc}\nResult: {result!r}"
+        ) from exc
+
+
+@then("the result should contain the expected keys")
+def step_result_contains_expected_keys(context: Any) -> None:
+    """Assert the JSON result contains expected keys."""
+    result = json.loads(context.format_result)
+    assert "plan_id" in result, f"Missing 'plan_id' in result: {result}"
+    assert "status" in result, f"Missing 'status' in result: {result}"
+
+
+@then("the result should be valid YAML")
+def step_result_is_valid_yaml(context: Any) -> None:
+    """Assert the result is valid YAML."""
+    result = context.format_result
+    assert isinstance(result, str), f"Expected str, got {type(result)}"
+    try:
+        parsed = yaml.safe_load(result)
+        assert parsed is not None, "YAML parsed to None"
+    except yaml.YAMLError as exc:
+        raise AssertionError(
+            f"Result is not valid YAML: {exc}\nResult: {result!r}"
+        ) from exc
+
+
+@then("the result should contain key-value pairs")
+def step_result_contains_key_value_pairs(context: Any) -> None:
+    """Assert the plain result contains key-value pairs."""
+    result = context.format_result
+    assert "plan_id" in result, f"Missing 'plan_id' in plain output: {result!r}"
+    assert "status" in result, f"Missing 'status' in plain output: {result!r}"
+
+
+@then("the result should contain column headers")
+def step_result_contains_column_headers(context: Any) -> None:
+    """Assert the table result contains column headers."""
+    result = context.format_result
+    assert "plan_id" in result, f"Missing 'plan_id' column in table: {result!r}"
+    assert "status" in result, f"Missing 'status' column in table: {result!r}"
+
+
+@then('the result should be "(empty)"')
+def step_result_is_empty(context: Any) -> None:
+    """Assert the result is the empty placeholder."""
+    assert context.format_result == "(empty)", (
+        f"Expected '(empty)', got: {context.format_result!r}"
+    )
+
+
+@then("the result should contain nested key-value pairs")
+def step_result_contains_nested_pairs(context: Any) -> None:
+    """Assert the plain result contains nested key-value pairs."""
+    result = context.format_result
+    assert "plan_id" in result, f"Missing 'plan_id' in plain output: {result!r}"
+    assert "metadata" in result, f"Missing 'metadata' in plain output: {result!r}"
diff --git a/pyproject.toml b/pyproject.toml
index 09960045b..1479fdebc 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -84,6 +84,8 @@ dev = [
     "vulture>=2.10",
     # Complexity metrics
     "radon>=6.0.1",
+    # Import boundary enforcement
+    "import-linter>=2.0",
 ]
 tests = [
     "behave==1.3.3",
diff --git a/src/cleveragents/application/services/plan_apply_service.py b/src/cleveragents/application/services/plan_apply_service.py
index bf7bee8a6..78a4e9387 100644
--- a/src/cleveragents/application/services/plan_apply_service.py
+++ b/src/cleveragents/application/services/plan_apply_service.py
@@ -646,7 +646,7 @@ class PlanApplyService:
         Returns:
             Rendered artifacts string.
         """
-        from cleveragents.cli.formatting import format_output
+        from cleveragents.shared.output_format import format_data as format_output
 
         plan = self._lifecycle.get_plan(plan_id)
         changeset = self._resolve_changeset(plan)
diff --git a/src/cleveragents/shared/output_format.py b/src/cleveragents/shared/output_format.py
new file mode 100644
index 000000000..8e684275c
--- /dev/null
+++ b/src/cleveragents/shared/output_format.py
@@ -0,0 +1,164 @@
+"""Shared output formatting utilities for cross-layer use.
+
+Provides lightweight serialisation helpers (JSON, YAML, plain text, ASCII
+table) that can be used by any layer without importing from the CLI
+presentation layer.
+
+This module intentionally has **no** dependencies on ``cleveragents.cli.*``
+so that Application and Domain layer code can format data for output without
+creating a reverse dependency on the Presentation layer.
+
+For full-featured CLI output (Rich console, colour, envelope wrapping, etc.)
+use ``cleveragents.cli.formatting`` instead.
+"""
+
+from __future__ import annotations
+
+import json
+from datetime import datetime
+from enum import Enum
+from io import StringIO
+from typing import Any
+
+import yaml
+from rich.console import Console
+from rich.table import Table
+
+
+def _serialize_value(value: Any) -> Any:
+    """Recursively normalise values for JSON/YAML serialisation.
+
+    * ``datetime`` -> ISO-8601 string
+    * ``Enum``     -> ``.value``
+    * ``dict``     -> recursed
+    * ``list``     -> recursed
+    * everything else -> unchanged
+    """
+    if isinstance(value, datetime):
+        return value.isoformat()
+    if isinstance(value, Enum):
+        return value.value
+    if isinstance(value, dict):
+        return {k: _serialize_value(v) for k, v in value.items()}
+    if isinstance(value, list):
+        return [_serialize_value(item) for item in value]
+    return value
+
+
+def format_as_json(data: dict[str, Any] | list[dict[str, Any]]) -> str:
+    """Render *data* as indented JSON."""
+    return json.dumps(_serialize_value(data), indent=2, default=str)
+
+
+def format_as_yaml(data: dict[str, Any] | list[dict[str, Any]]) -> str:
+    """Render *data* as YAML."""
+    return yaml.dump(
+        _serialize_value(data),
+        default_flow_style=False,
+        sort_keys=False,
+        allow_unicode=True,
+    ).rstrip("\n")
+
+
+def format_as_plain(data: dict[str, Any] | list[dict[str, Any]]) -> str:
+    """Render *data* as plain ``key: value`` lines."""
+    if isinstance(data, list):
+        parts: list[str] = []
+        for idx, item in enumerate(data):
+            if idx > 0:
+                parts.append("---")
+            parts.append(_format_plain_dict(item))
+        return "\n".join(parts)
+    return _format_plain_dict(data)
+
+
+def _format_plain_dict(data: dict[str, Any]) -> str:
+    lines: list[str] = []
+    for key, value in data.items():
+        serialised = _serialize_value(value)
+        if isinstance(serialised, dict):
+            lines.append(f"{key}:")
+            for k2, v2 in serialised.items():
+                lines.append(f"  {k2}: {v2}")
+        elif isinstance(serialised, list):
+            lines.append(f"{key}:")
+            for item in serialised:
+                if isinstance(item, dict):
+                    lines.append(f"  - {json.dumps(item, default=str)}")
+                else:
+                    lines.append(f"  - {item}")
+        else:
+            lines.append(f"{key}: {serialised}")
+    return "\n".join(lines)
+
+
+def format_as_table(data: dict[str, Any] | list[dict[str, Any]]) -> str:
+    """Render *data* as an ASCII table (no Rich styling)."""
+    rows: list[dict[str, Any]] = [data] if isinstance(data, dict) else data
+
+    if not rows:
+        return "(empty)"
+
+    columns: list[str] = list(rows[0].keys())
+    for row in rows[1:]:
+        for key in row:
+            if key not in columns:
+                columns.append(key)
+
+    table = Table(show_header=True, show_edge=True)
+    for col in columns:
+        table.add_column(col)
+    for row in rows:
+        cells: list[str] = []
+        for col in columns:
+            val = row.get(col, "")
+            serialised = _serialize_value(val)
+            if isinstance(serialised, (dict, list)):
+                cells.append(json.dumps(serialised, default=str))
+            else:
+                cells.append(str(serialised))
+        table.add_row(*cells)
+
+    buf = StringIO()
+    console = Console(file=buf, width=200, no_color=True)
+    console.print(table)
+    return buf.getvalue().rstrip("\n")
+
+
+def format_data(
+    data: dict[str, Any] | list[dict[str, Any]],
+    format_type: str,
+) -> str:
+    """Format *data* according to *format_type*.
+
+    Supported format types: ``json``, ``yaml``, ``plain``, ``table``.
+    Any other value falls back to JSON.
+
+    This function is intentionally minimal -- it does **not** wrap output in
+    the CLI envelope (``command``, ``status``, ``exit_code``, etc.) and does
+    **not** write to ``sys.stdout`` directly.  It simply returns the rendered
+    string so the caller can decide what to do with it.
+
+    For full CLI output with envelope and Rich console support use
+    ``cleveragents.cli.formatting.format_output`` instead.
+    """
+    fmt = format_type.lower()
+    if fmt == "json":
+        return format_as_json(data)
+    if fmt == "yaml":
+        return format_as_yaml(data)
+    if fmt == "plain":
+        return format_as_plain(data)
+    if fmt == "table":
+        return format_as_table(data)
+    # Fallback: JSON
+    return format_as_json(data)
+
+
+__all__ = [
+    "format_as_json",
+    "format_as_plain",
+    "format_as_table",
+    "format_as_yaml",
+    "format_data",
+]