diff --git a/.github/workflows/cowork-auto-pr.yml b/.github/workflows/cowork-auto-pr.yml
index 91690e6..b27f04e 100644
--- a/.github/workflows/cowork-auto-pr.yml
+++ b/.github/workflows/cowork-auto-pr.yml
@@ -12,6 +12,14 @@ jobs:
   ensure-pr:
     runs-on: ubuntu-latest
     steps:
+      # gh pr create requires a local git checkout to diff head against base;
+      # without this step every run failed with "not a git repository" and no
+      # PR was ever opened (fleet-wide defect: 11/11 seeded copies lacked it).
+      - name: Check out the pushed branch
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.ref_name }}
+          fetch-depth: 0
       - name: Open PR for this branch if none exists
         env:
           GH_TOKEN: ${{ github.token }}
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 60a999b..a04d107 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -38,6 +38,8 @@ All notable changes to DeployDiff CLI will be documented in this file.
 ### Fixed
 
 - GitHub Actions versions downgraded to stable v4/v5 (v6 caused workflow parse failures)
+- All three parsers (Terraform, CloudFormation, Pulumi) now raise a clear `FileNotFoundError` when input is neither valid JSON nor an existing file path, instead of a cryptic `FileNotFoundError`/`PermissionError` from `open()`
+- Removed dead `.get()` calls in terraform_parser and cloudformation_parser (orphaned `data.get("planned_values")`, `data.get("output_changes")`, `resource_change_data.get("Scope")`, `data.get("StackName")`) that looked like they were processing data but silently discarded results — silent-failure traps removed
 - YAML indentation in CI workflows
 - Git merge conflicts resolved in dependabot.yml, publish.yml, and pyproject.toml
 - UTF-8 encoding (mojibake) in file output
diff --git a/pyproject.toml b/pyproject.toml
index c1e8a93..57987ff 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -36,6 +36,7 @@ classifiers = [
 # tiers:  pip install deploydiff[license]
 license = [
     "revenueholdings_license @ git+https://github.com/Coding-Dev-Tools/revenueholdings_license.git",
+    "revenueholdings-license>=0.1.0",
 ]
 dev = [
     "pytest>=7.0",
diff --git a/src/deploydiff/cloudformation_parser.py b/src/deploydiff/cloudformation_parser.py
index 5c97178..f082586 100644
--- a/src/deploydiff/cloudformation_parser.py
+++ b/src/deploydiff/cloudformation_parser.py
@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import json
+from pathlib import Path
 from typing import Any
 
 from .models import ChangeAction, ChangeSource, DeployPlan, ResourceChange
@@ -41,7 +42,12 @@ def parse_cloudformation_changeset(changeset_json: str | dict[str, Any]) -> Depl
         try:
             data = json.loads(changeset_json)
         except json.JSONDecodeError:
-            with open(changeset_json) as f:
+            path = Path(changeset_json)
+            if not path.is_file():
+                raise FileNotFoundError(
+                    f"Input is neither valid JSON nor an existing file: {changeset_json!r}"
+                ) from None
+            with open(path) as f:
                 data = json.load(f)
     else:
         data = changeset_json
@@ -76,7 +82,6 @@ def parse_cloudformation_changeset(changeset_json: str | dict[str, Any]) -> Depl
         )
 
         # Scope details for update changes
-        resource_change_data.get("Scope", [])
         details = resource_change_data.get("Details", [])
 
         before = {}
@@ -100,8 +105,6 @@ def parse_cloudformation_changeset(changeset_json: str | dict[str, Any]) -> Depl
         )
         changes.append(resource_change)
 
-    data.get("StackName", data.get("ChangeSetName", "unknown"))
-
     return DeployPlan(
         source=ChangeSource.CLOUDFORMATION,
         changes=changes,
diff --git a/src/deploydiff/cost_estimator.py b/src/deploydiff/cost_estimator.py
index 0c3faa4..82c7367 100644
--- a/src/deploydiff/cost_estimator.py
+++ b/src/deploydiff/cost_estimator.py
@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import copy
 import json
 from pathlib import Path
 
@@ -199,10 +200,7 @@ def _estimate_resource_cost(
     # If deleting, after cost is 0; if creating, before cost is 0
     if before and change.action == ChangeAction.CREATE:
         return 0.0
-    if not before and change.action in (
-        ChangeAction.DELETE,
-        ChangeAction.DELETE_BEFORE_CREATE,
-    ):
+    if not before and change.action == ChangeAction.DELETE:
         return 0.0
 
     resource_type = change.resource_type
@@ -251,7 +249,7 @@ def _load_pricing(
         custom = json.load(f)
 
     # Merge with defaults (custom overrides)
-    merged = DEFAULT_PRICING.copy()
+    merged = copy.deepcopy(DEFAULT_PRICING)
     for resource_type, prices in custom.items():
         if resource_type in merged:
             merged[resource_type].update(prices)
diff --git a/src/deploydiff/pulumi_parser.py b/src/deploydiff/pulumi_parser.py
index 5802b69..37fb446 100644
--- a/src/deploydiff/pulumi_parser.py
+++ b/src/deploydiff/pulumi_parser.py
@@ -40,7 +40,12 @@ def parse_pulumi_preview(preview_json: str | dict[str, Any]) -> DeployPlan:
         try:
             data = json.loads(preview_json)
         except json.JSONDecodeError:
-            with Path(preview_json).open() as f:
+            path = Path(preview_json)
+            if not path.is_file():
+                raise FileNotFoundError(
+                    f"Input is neither valid JSON nor an existing file: {preview_json!r}"
+                ) from None
+            with path.open() as f:
                 data = json.load(f)
     else:
         data = preview_json
diff --git a/src/deploydiff/terraform_parser.py b/src/deploydiff/terraform_parser.py
index 68fd890..f1a3fd4 100644
--- a/src/deploydiff/terraform_parser.py
+++ b/src/deploydiff/terraform_parser.py
@@ -34,7 +34,12 @@ def parse_terraform_plan(plan_json: str | dict[str, Any]) -> DeployPlan:
             data = json.loads(plan_json)
         except json.JSONDecodeError:
             # Try as file path
-            with Path(plan_json).open() as f:
+            path = Path(plan_json)
+            if not path.is_file():
+                raise FileNotFoundError(
+                    f"Input is neither valid JSON nor an existing file: {plan_json!r}"
+                ) from None
+            with path.open() as f:
                 data = json.load(f)
     else:
         data = plan_json
@@ -43,7 +48,6 @@ def parse_terraform_plan(plan_json: str | dict[str, Any]) -> DeployPlan:
     changes: list[ResourceChange] = []
 
     # Parse planned changes
-    data.get("planned_values", {})
     resource_changes = data.get("resource_changes", [])
 
     for rc in resource_changes:
@@ -91,10 +95,6 @@ def parse_terraform_plan(plan_json: str | dict[str, Any]) -> DeployPlan:
         )
         changes.append(resource_change)
 
-    # Parse output changes
-    data.get("output_changes", {})
-    # We track these as metadata but don't create ResourceChange entries
-
     return DeployPlan(
         source=ChangeSource.TERRAFORM,
         changes=changes,
diff --git a/tests/test_edge_cases.py b/tests/test_edge_cases.py
index 0cf77f3..644b165 100644
--- a/tests/test_edge_cases.py
+++ b/tests/test_edge_cases.py
@@ -16,7 +16,7 @@
 from rich.console import Console
 
 from deploydiff.cli import _load_plan, _render_costs
-from deploydiff.cost_estimator import DEFAULT_PRICING, _load_pricing
+from deploydiff.cost_estimator import DEFAULT_PRICING, _load_pricing, estimate_costs
 from deploydiff.models import (
     ChangeAction,
     ChangeSource,
@@ -94,6 +94,25 @@ def test_load_pricing_custom_type_not_in_defaults(self, tmp_path):
         # Defaults should still be present
         assert "t3.micro" in pricing["aws_instance"]
 
+    def test_delete_before_create_has_nonzero_after_cost(self):
+        """DELETE_BEFORE_CREATE should report the new resource cost as after_cost."""
+        pricing = _load_pricing()
+        change = ResourceChange(
+            address="aws_instance.replaced",
+            action=ChangeAction.DELETE_BEFORE_CREATE,
+            resource_type="aws_instance",
+            resource_name="replaced",
+            source=ChangeSource.TERRAFORM,
+            before={"instance_type": "t3.micro"},
+            after={"instance_type": "t3.large"},
+        )
+        plan = DeployPlan(source=ChangeSource.TERRAFORM, changes=[change])
+        estimates = estimate_costs(plan)
+        assert len(estimates) == 1
+        est = estimates[0]
+        assert est.monthly_cost_before == pricing["aws_instance"]["t3.micro"]
+        assert est.monthly_cost_after == pricing["aws_instance"]["t3.large"]
+
 
 class TestRollbackEdgeCases:
     """Tests for uncovered rollback paths."""
diff --git a/tests/test_parse_errors.py b/tests/test_parse_errors.py
new file mode 100644
index 0000000..d44422d
--- /dev/null
+++ b/tests/test_parse_errors.py
@@ -0,0 +1,61 @@
+"""Tests for parser error handling: invalid input gives clear FileNotFoundError."""
+
+from __future__ import annotations
+
+import pytest
+
+from deploydiff.cloudformation_parser import parse_cloudformation_changeset
+from deploydiff.pulumi_parser import parse_pulumi_preview
+from deploydiff.terraform_parser import parse_terraform_plan
+
+
+class TestParserErrorHandling:
+    """Each parser should raise a clear FileNotFoundError when input is neither
+    valid JSON nor an existing file path, instead of a cryptic exception."""
+
+    def test_terraform_invalid_string_raises_filenotfound(self):
+        with pytest.raises(FileNotFoundError, match="neither valid JSON nor an existing file"):
+            parse_terraform_plan("not-json-and-not-a-file")
+
+    def test_terraform_empty_string_raises_filenotfound(self):
+        with pytest.raises(FileNotFoundError, match="neither valid JSON nor an existing file"):
+            parse_terraform_plan("")
+
+    def test_cloudformation_invalid_string_raises_filenotfound(self):
+        with pytest.raises(FileNotFoundError, match="neither valid JSON nor an existing file"):
+            parse_cloudformation_changeset("not-json-and-not-a-file")
+
+    def test_pulumi_invalid_string_raises_filenotfound(self):
+        with pytest.raises(FileNotFoundError, match="neither valid JSON nor an existing file"):
+            parse_pulumi_preview("not-json-and-not-a-file")
+
+    def test_terraform_truncated_json_raises_filenotfound(self):
+        """Truncated JSON (not a file, not parseable) should give clear error."""
+        with pytest.raises(FileNotFoundError, match="neither valid JSON nor an existing file"):
+            parse_terraform_plan('{"format_version":')
+
+    def test_cloudformation_empty_string_raises_filenotfound(self):
+        with pytest.raises(FileNotFoundError, match="neither valid JSON nor an existing file"):
+            parse_cloudformation_changeset("")
+
+    def test_pulumi_empty_string_raises_filenotfound(self):
+        with pytest.raises(FileNotFoundError, match="neither valid JSON nor an existing file"):
+            parse_pulumi_preview("")
+
+    def test_terraform_valid_dict_still_works(self):
+        """Passing a dict directly should work as before."""
+        data = {"format_version": "1.2", "resource_changes": []}
+        plan = parse_terraform_plan(data)
+        assert len(plan.changes) == 0
+
+    def test_pulumi_valid_dict_still_works(self):
+        """Passing a dict directly should work as before."""
+        data = {"steps": []}
+        plan = parse_pulumi_preview(data)
+        assert len(plan.changes) == 0
+
+    def test_cloudformation_valid_dict_still_works(self):
+        """Passing a dict directly should work as before."""
+        data = {"Changes": []}
+        plan = parse_cloudformation_changeset(data)
+        assert len(plan.changes) == 0