chore: switch from gob to JSON encoding for digests

The gob encoder is dependent on the order in which it sees types. So,
even encoding a completely new type could change the "digest" of a type
with the same values. This is not in the flavor or producing a digest.

This change switches to JSON, which will produce a consistent encoding.

Signed-off-by: Donnie Adams <donnie@acorn.io>

Author: thedadams

pkg/hash/sha256.go

@@ -2,8 +2,8 @@ package hash
 
 import (
 	"crypto/sha256"
-	"encoding/gob"
 	"encoding/hex"
+	"encoding/json"
 )
 
 func ID(parts ...string) string {
@@ -26,7 +26,7 @@ func Digest(obj any) string {
 	case string:
 		hash.Write([]byte(v))
 	default:
-		if err := gob.NewEncoder(hash).Encode(obj); err != nil {
+		if err := json.NewEncoder(hash).Encode(obj); err != nil {
 			panic(err)
 		}
 	}

pkg/tests/runner2_test.go

@@ -313,7 +313,7 @@ name: mcp
       ],
       "type": "object"
     },
-    "instructions": "#!sys.mcp.invoke.append_insight c358c2eb93fa9a98631cd9e4f324d7b59f56aee11c7ae32a00984ad5844dc32c",
+    "instructions": "#!sys.mcp.invoke.append_insight e592cc0c9483290685611ba70bd8595829cc794f7eae0419eabb3388bf0d3529",
     "id": "inline:append_insight",
     "localTools": {
       "append_insight": "inline:append_insight",
@@ -346,7 +346,7 @@ name: mcp
       ],
       "type": "object"
     },
-    "instructions": "#!sys.mcp.invoke.create_table c358c2eb93fa9a98631cd9e4f324d7b59f56aee11c7ae32a00984ad5844dc32c",
+    "instructions": "#!sys.mcp.invoke.create_table e592cc0c9483290685611ba70bd8595829cc794f7eae0419eabb3388bf0d3529",
     "id": "inline:create_table",
     "localTools": {
       "append_insight": "inline:append_insight",
@@ -379,7 +379,7 @@ name: mcp
       ],
       "type": "object"
     },
-    "instructions": "#!sys.mcp.invoke.describe_table c358c2eb93fa9a98631cd9e4f324d7b59f56aee11c7ae32a00984ad5844dc32c",
+    "instructions": "#!sys.mcp.invoke.describe_table e592cc0c9483290685611ba70bd8595829cc794f7eae0419eabb3388bf0d3529",
     "id": "inline:describe_table",
     "localTools": {
       "append_insight": "inline:append_insight",
@@ -403,7 +403,7 @@ name: mcp
     "arguments": {
       "type": "object"
     },
-    "instructions": "#!sys.mcp.invoke.list_tables c358c2eb93fa9a98631cd9e4f324d7b59f56aee11c7ae32a00984ad5844dc32c",
+    "instructions": "#!sys.mcp.invoke.list_tables e592cc0c9483290685611ba70bd8595829cc794f7eae0419eabb3388bf0d3529",
     "id": "inline:list_tables",
     "localTools": {
       "append_insight": "inline:append_insight",
@@ -505,7 +505,7 @@ name: mcp
       ],
       "type": "object"
     },
-    "instructions": "#!sys.mcp.invoke.read_query c358c2eb93fa9a98631cd9e4f324d7b59f56aee11c7ae32a00984ad5844dc32c",
+    "instructions": "#!sys.mcp.invoke.read_query e592cc0c9483290685611ba70bd8595829cc794f7eae0419eabb3388bf0d3529",
     "id": "inline:read_query",
     "localTools": {
       "append_insight": "inline:append_insight",
@@ -538,7 +538,7 @@ name: mcp
       ],
       "type": "object"
     },
-    "instructions": "#!sys.mcp.invoke.write_query c358c2eb93fa9a98631cd9e4f324d7b59f56aee11c7ae32a00984ad5844dc32c",
+    "instructions": "#!sys.mcp.invoke.write_query e592cc0c9483290685611ba70bd8595829cc794f7eae0419eabb3388bf0d3529",
     "id": "inline:write_query",
     "localTools": {
       "append_insight": "inline:append_insight",