diff --git a/.claude/hooks/pre-compact-snapshot.sh b/.claude/hooks/pre-compact-snapshot.sh
index c37da0b..699049d 100755
--- a/.claude/hooks/pre-compact-snapshot.sh
+++ b/.claude/hooks/pre-compact-snapshot.sh
@@ -131,24 +131,29 @@ else:
     auto_ratio_pm = 0
 
 print(f'{turns}\t{input_tokens}\t{cache_creation}\t{cache_read}\t{output_tokens}\t{model_id}\t{auto_ratio_pm}\t{user_tokens_est}\t{unique_files}\t{total_edits}\t{test_passes}\t{test_failures}\t{has_public_push}')
+# Second line: JSON array of edited files with counts
+print(json.dumps(edited_files))
 " "$TRANSCRIPT_PATH" 2>/dev/null || echo "")
 
-  if [ -n "$USAGE_DATA" ] && [ "$(echo "$USAGE_DATA" | cut -f1)" -gt 0 ] 2>/dev/null; then
+  USAGE_LINE1=$(echo "$USAGE_DATA" | head -1)
+  EDITED_FILES_JSON=$(echo "$USAGE_DATA" | tail -1)
+
+  if [ -n "$USAGE_LINE1" ] && [ "$(echo "$USAGE_LINE1" | cut -f1)" -gt 0 ] 2>/dev/null; then
     # Actual token counts available
     TOKEN_SOURCE="actual"
-    ASSISTANT_TURNS=$(echo "$USAGE_DATA" | cut -f1)
-    INPUT_TOKENS=$(echo "$USAGE_DATA" | cut -f2)
-    CACHE_CREATION=$(echo "$USAGE_DATA" | cut -f3)
-    CACHE_READ=$(echo "$USAGE_DATA" | cut -f4)
-    OUTPUT_TOKENS=$(echo "$USAGE_DATA" | cut -f5)
-    MODEL_ID=$(echo "$USAGE_DATA" | cut -f6)
-    AUTO_RATIO_PM=$(echo "$USAGE_DATA" | cut -f7)
-    USER_TOKENS_EST=$(echo "$USAGE_DATA" | cut -f8)
-    UNIQUE_FILES=$(echo "$USAGE_DATA" | cut -f9)
-    TOTAL_EDITS=$(echo "$USAGE_DATA" | cut -f10)
-    TEST_PASSES=$(echo "$USAGE_DATA" | cut -f11)
-    TEST_FAILURES=$(echo "$USAGE_DATA" | cut -f12)
-    HAS_PUBLIC_PUSH=$(echo "$USAGE_DATA" | cut -f13)
+    ASSISTANT_TURNS=$(echo "$USAGE_LINE1" | cut -f1)
+    INPUT_TOKENS=$(echo "$USAGE_LINE1" | cut -f2)
+    CACHE_CREATION=$(echo "$USAGE_LINE1" | cut -f3)
+    CACHE_READ=$(echo "$USAGE_LINE1" | cut -f4)
+    OUTPUT_TOKENS=$(echo "$USAGE_LINE1" | cut -f5)
+    MODEL_ID=$(echo "$USAGE_LINE1" | cut -f6)
+    AUTO_RATIO_PM=$(echo "$USAGE_LINE1" | cut -f7)
+    USER_TOKENS_EST=$(echo "$USAGE_LINE1" | cut -f8)
+    UNIQUE_FILES=$(echo "$USAGE_LINE1" | cut -f9)
+    TOTAL_EDITS=$(echo "$USAGE_LINE1" | cut -f10)
+    TEST_PASSES=$(echo "$USAGE_LINE1" | cut -f11)
+    TEST_FAILURES=$(echo "$USAGE_LINE1" | cut -f12)
+    HAS_PUBLIC_PUSH=$(echo "$USAGE_LINE1" | cut -f13)
 
     # Cumulative input = all tokens that went through the model.
     # Cache reads are cheaper (~10-20% of full compute), so we weight them.
@@ -184,6 +189,7 @@ print(f'{turns}\t{input_tokens}\t{cache_creation}\t{cache_read}\t{output_tokens}
     TEST_PASSES=0
     TEST_FAILURES=0
     HAS_PUBLIC_PUSH=0
+    EDITED_FILES_JSON="{}"
   fi
 
   # --- Cost estimates ---
@@ -226,12 +232,48 @@ else
   TEST_PASSES=0
   TEST_FAILURES=0
   HAS_PUBLIC_PUSH=0
+  EDITED_FILES_JSON="{}"
 fi
 
 # --- Write log entry ---
 
-cat >> "$LOG_FILE" <<EOF
-{"timestamp":"$TIMESTAMP","session_id":"$SESSION_ID","trigger":"$TRIGGER","token_source":"$TOKEN_SOURCE","transcript_bytes":$TRANSCRIPT_BYTES,"transcript_lines":$TRANSCRIPT_LINES,"assistant_turns":$ASSISTANT_TURNS,"tool_uses":$TOOL_USES,"cumulative_input_tokens":$CUMULATIVE_INPUT,"cumulative_input_raw":$CUMULATIVE_INPUT_RAW,"cache_creation_tokens":$CACHE_CREATION,"cache_read_tokens":$CACHE_READ,"output_tokens":$OUTPUT_TOKENS,"energy_wh":$ENERGY_WH,"co2_g":$CO2_G,"cost_cents":$COST_CENTS,"model_id":"$MODEL_ID","automation_ratio_pm":$AUTO_RATIO_PM,"user_tokens_est":$USER_TOKENS_EST,"unique_files_edited":$UNIQUE_FILES,"total_file_edits":$TOTAL_EDITS,"test_passes":$TEST_PASSES,"test_failures":$TEST_FAILURES,"has_public_push":$HAS_PUBLIC_PUSH}
-EOF
+# Build log entry using Python to safely embed the edited_files JSON
+python3 -c "
+import json, sys
+entry = {
+    'timestamp': sys.argv[1],
+    'session_id': sys.argv[2],
+    'trigger': sys.argv[3],
+    'token_source': sys.argv[4],
+    'transcript_bytes': int(sys.argv[5]),
+    'transcript_lines': int(sys.argv[6]),
+    'assistant_turns': int(sys.argv[7]),
+    'tool_uses': int(sys.argv[8]),
+    'cumulative_input_tokens': int(sys.argv[9]),
+    'cumulative_input_raw': int(sys.argv[10]),
+    'cache_creation_tokens': int(sys.argv[11]),
+    'cache_read_tokens': int(sys.argv[12]),
+    'output_tokens': int(sys.argv[13]),
+    'energy_wh': int(sys.argv[14]),
+    'co2_g': int(sys.argv[15]),
+    'cost_cents': int(sys.argv[16]),
+    'model_id': sys.argv[17],
+    'automation_ratio_pm': int(sys.argv[18]),
+    'user_tokens_est': int(sys.argv[19]),
+    'unique_files_edited': int(sys.argv[20]),
+    'total_file_edits': int(sys.argv[21]),
+    'test_passes': int(sys.argv[22]),
+    'test_failures': int(sys.argv[23]),
+    'has_public_push': int(sys.argv[24]),
+    'edited_files': json.loads(sys.argv[25]),
+}
+print(json.dumps(entry, separators=(',', ':')))
+" "$TIMESTAMP" "$SESSION_ID" "$TRIGGER" "$TOKEN_SOURCE" \
+  "$TRANSCRIPT_BYTES" "$TRANSCRIPT_LINES" "$ASSISTANT_TURNS" "$TOOL_USES" \
+  "$CUMULATIVE_INPUT" "$CUMULATIVE_INPUT_RAW" "$CACHE_CREATION" "$CACHE_READ" \
+  "$OUTPUT_TOKENS" "$ENERGY_WH" "$CO2_G" "$COST_CENTS" \
+  "$MODEL_ID" "$AUTO_RATIO_PM" "$USER_TOKENS_EST" \
+  "$UNIQUE_FILES" "$TOTAL_EDITS" "$TEST_PASSES" "$TEST_FAILURES" \
+  "$HAS_PUBLIC_PUSH" "$EDITED_FILES_JSON" >> "$LOG_FILE"
 
 exit 0
diff --git a/impact-toolkit/hooks/pre-compact-snapshot.sh b/impact-toolkit/hooks/pre-compact-snapshot.sh
index c37da0b..699049d 100755
--- a/impact-toolkit/hooks/pre-compact-snapshot.sh
+++ b/impact-toolkit/hooks/pre-compact-snapshot.sh
@@ -131,24 +131,29 @@ else:
     auto_ratio_pm = 0
 
 print(f'{turns}\t{input_tokens}\t{cache_creation}\t{cache_read}\t{output_tokens}\t{model_id}\t{auto_ratio_pm}\t{user_tokens_est}\t{unique_files}\t{total_edits}\t{test_passes}\t{test_failures}\t{has_public_push}')
+# Second line: JSON array of edited files with counts
+print(json.dumps(edited_files))
 " "$TRANSCRIPT_PATH" 2>/dev/null || echo "")
 
-  if [ -n "$USAGE_DATA" ] && [ "$(echo "$USAGE_DATA" | cut -f1)" -gt 0 ] 2>/dev/null; then
+  USAGE_LINE1=$(echo "$USAGE_DATA" | head -1)
+  EDITED_FILES_JSON=$(echo "$USAGE_DATA" | tail -1)
+
+  if [ -n "$USAGE_LINE1" ] && [ "$(echo "$USAGE_LINE1" | cut -f1)" -gt 0 ] 2>/dev/null; then
     # Actual token counts available
     TOKEN_SOURCE="actual"
-    ASSISTANT_TURNS=$(echo "$USAGE_DATA" | cut -f1)
-    INPUT_TOKENS=$(echo "$USAGE_DATA" | cut -f2)
-    CACHE_CREATION=$(echo "$USAGE_DATA" | cut -f3)
-    CACHE_READ=$(echo "$USAGE_DATA" | cut -f4)
-    OUTPUT_TOKENS=$(echo "$USAGE_DATA" | cut -f5)
-    MODEL_ID=$(echo "$USAGE_DATA" | cut -f6)
-    AUTO_RATIO_PM=$(echo "$USAGE_DATA" | cut -f7)
-    USER_TOKENS_EST=$(echo "$USAGE_DATA" | cut -f8)
-    UNIQUE_FILES=$(echo "$USAGE_DATA" | cut -f9)
-    TOTAL_EDITS=$(echo "$USAGE_DATA" | cut -f10)
-    TEST_PASSES=$(echo "$USAGE_DATA" | cut -f11)
-    TEST_FAILURES=$(echo "$USAGE_DATA" | cut -f12)
-    HAS_PUBLIC_PUSH=$(echo "$USAGE_DATA" | cut -f13)
+    ASSISTANT_TURNS=$(echo "$USAGE_LINE1" | cut -f1)
+    INPUT_TOKENS=$(echo "$USAGE_LINE1" | cut -f2)
+    CACHE_CREATION=$(echo "$USAGE_LINE1" | cut -f3)
+    CACHE_READ=$(echo "$USAGE_LINE1" | cut -f4)
+    OUTPUT_TOKENS=$(echo "$USAGE_LINE1" | cut -f5)
+    MODEL_ID=$(echo "$USAGE_LINE1" | cut -f6)
+    AUTO_RATIO_PM=$(echo "$USAGE_LINE1" | cut -f7)
+    USER_TOKENS_EST=$(echo "$USAGE_LINE1" | cut -f8)
+    UNIQUE_FILES=$(echo "$USAGE_LINE1" | cut -f9)
+    TOTAL_EDITS=$(echo "$USAGE_LINE1" | cut -f10)
+    TEST_PASSES=$(echo "$USAGE_LINE1" | cut -f11)
+    TEST_FAILURES=$(echo "$USAGE_LINE1" | cut -f12)
+    HAS_PUBLIC_PUSH=$(echo "$USAGE_LINE1" | cut -f13)
 
     # Cumulative input = all tokens that went through the model.
     # Cache reads are cheaper (~10-20% of full compute), so we weight them.
@@ -184,6 +189,7 @@ print(f'{turns}\t{input_tokens}\t{cache_creation}\t{cache_read}\t{output_tokens}
     TEST_PASSES=0
     TEST_FAILURES=0
     HAS_PUBLIC_PUSH=0
+    EDITED_FILES_JSON="{}"
   fi
 
   # --- Cost estimates ---
@@ -226,12 +232,48 @@ else
   TEST_PASSES=0
   TEST_FAILURES=0
   HAS_PUBLIC_PUSH=0
+  EDITED_FILES_JSON="{}"
 fi
 
 # --- Write log entry ---
 
-cat >> "$LOG_FILE" <<EOF
-{"timestamp":"$TIMESTAMP","session_id":"$SESSION_ID","trigger":"$TRIGGER","token_source":"$TOKEN_SOURCE","transcript_bytes":$TRANSCRIPT_BYTES,"transcript_lines":$TRANSCRIPT_LINES,"assistant_turns":$ASSISTANT_TURNS,"tool_uses":$TOOL_USES,"cumulative_input_tokens":$CUMULATIVE_INPUT,"cumulative_input_raw":$CUMULATIVE_INPUT_RAW,"cache_creation_tokens":$CACHE_CREATION,"cache_read_tokens":$CACHE_READ,"output_tokens":$OUTPUT_TOKENS,"energy_wh":$ENERGY_WH,"co2_g":$CO2_G,"cost_cents":$COST_CENTS,"model_id":"$MODEL_ID","automation_ratio_pm":$AUTO_RATIO_PM,"user_tokens_est":$USER_TOKENS_EST,"unique_files_edited":$UNIQUE_FILES,"total_file_edits":$TOTAL_EDITS,"test_passes":$TEST_PASSES,"test_failures":$TEST_FAILURES,"has_public_push":$HAS_PUBLIC_PUSH}
-EOF
+# Build log entry using Python to safely embed the edited_files JSON
+python3 -c "
+import json, sys
+entry = {
+    'timestamp': sys.argv[1],
+    'session_id': sys.argv[2],
+    'trigger': sys.argv[3],
+    'token_source': sys.argv[4],
+    'transcript_bytes': int(sys.argv[5]),
+    'transcript_lines': int(sys.argv[6]),
+    'assistant_turns': int(sys.argv[7]),
+    'tool_uses': int(sys.argv[8]),
+    'cumulative_input_tokens': int(sys.argv[9]),
+    'cumulative_input_raw': int(sys.argv[10]),
+    'cache_creation_tokens': int(sys.argv[11]),
+    'cache_read_tokens': int(sys.argv[12]),
+    'output_tokens': int(sys.argv[13]),
+    'energy_wh': int(sys.argv[14]),
+    'co2_g': int(sys.argv[15]),
+    'cost_cents': int(sys.argv[16]),
+    'model_id': sys.argv[17],
+    'automation_ratio_pm': int(sys.argv[18]),
+    'user_tokens_est': int(sys.argv[19]),
+    'unique_files_edited': int(sys.argv[20]),
+    'total_file_edits': int(sys.argv[21]),
+    'test_passes': int(sys.argv[22]),
+    'test_failures': int(sys.argv[23]),
+    'has_public_push': int(sys.argv[24]),
+    'edited_files': json.loads(sys.argv[25]),
+}
+print(json.dumps(entry, separators=(',', ':')))
+" "$TIMESTAMP" "$SESSION_ID" "$TRIGGER" "$TOKEN_SOURCE" \
+  "$TRANSCRIPT_BYTES" "$TRANSCRIPT_LINES" "$ASSISTANT_TURNS" "$TOOL_USES" \
+  "$CUMULATIVE_INPUT" "$CUMULATIVE_INPUT_RAW" "$CACHE_CREATION" "$CACHE_READ" \
+  "$OUTPUT_TOKENS" "$ENERGY_WH" "$CO2_G" "$COST_CENTS" \
+  "$MODEL_ID" "$AUTO_RATIO_PM" "$USER_TOKENS_EST" \
+  "$UNIQUE_FILES" "$TOTAL_EDITS" "$TEST_PASSES" "$TEST_FAILURES" \
+  "$HAS_PUBLIC_PUSH" "$EDITED_FILES_JSON" >> "$LOG_FILE"
 
 exit 0
diff --git a/tasks/README.md b/tasks/README.md
index e1ee318..14d4289 100644
--- a/tasks/README.md
+++ b/tasks/README.md
@@ -37,6 +37,7 @@ separately as handoffs.
 | 24 | Update show-impact.sh for new fields | quantify-social-costs | DONE | Social cost proxies displayed in impact viewer |
 | 25 | Update methodology confidence summary | quantify-social-costs | DONE | 4 categories moved to "Proxy", explanation added |
 | 26 | Build aggregate dashboard | quantify-social-costs | DONE | `show-aggregate.sh` — portfolio-level social cost metrics |
+| 27 | Log edited file list in hook | quantify-social-costs | DONE | `edited_files` dict in JSONL (file path → edit count) |
 
 ## Handoffs