v0.2.0: edges [N] section header and edges=N header field

Breaking: encode() and encode_with_session() now emit edges=N in header
and ## edges [N] as section header. decode() strips bracket suffix.

Author: blackwell-systems

CHANGELOG.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## v0.2.0 (2026-06-05)
+
+- **Breaking**: `encode()` now emits `edges=N` in header line
+- **Breaking**: `encode()` now emits `## edges [N]` section header (was `## edges`)
+- `decode()` updated to parse `## edges [N]` format (strips bracket suffix)
+- Session encoder updated to emit new edge count format
+
 ## v0.1.3 (2026-06-04)
 
 - Docs: update README for PyPI discoverability (gcformat.com, proxy, vs-toon links)

README.md

@@ -61,12 +61,12 @@ output = encode(p)
 
 Output:
 ```
-GCF tool=context_for_task budget=5000 tokens=1847 symbols=2
+GCF tool=context_for_task budget=5000 tokens=1847 symbols=2 edges=1
 ## targets
 @0 fn pkg.AuthMiddleware 0.78 lsp_resolved
 ## related
 @1 fn pkg.NewServer 0.54 lsp_resolved
-## edges
+## edges [1]
 @0<@1 calls
 ```
 

src/gcf/decode.py

@@ -51,6 +51,10 @@ def decode(input_text: str) -> Payload:
         # Group header.
         if line.startswith("## "):
             group = line[3:]
+            # Strip bracket suffix: "edges [200]" -> "edges"
+            bracket_idx = group.find(" [")
+            if bracket_idx >= 0:
+                group = group[:bracket_idx]
             in_edges = group == "edges"
             if not in_edges:
                 if group == "targets":

src/gcf/encode.py

@@ -17,17 +17,23 @@ def encode(p: Payload) -> str:
     """
     parts: list[str] = []
 
-    # Header line.
-    header = f"GCF tool={p.tool} budget={p.token_budget} tokens={p.tokens_used} symbols={len(p.symbols)}"
-    if p.pack_root:
-        header += f" pack_root={p.pack_root}"
-    parts.append(header)
-
     # Build symbol index for edge references.
     sym_index: dict[str, int] = {}
     for i, s in enumerate(p.symbols):
         sym_index[s.qualified_name] = i
 
+    # Count valid edges (both endpoints in symbol index).
+    valid_edges = sum(
+        1 for e in p.edges
+        if e.source in sym_index and e.target in sym_index
+    )
+
+    # Header line.
+    header = f"GCF tool={p.tool} budget={p.token_budget} tokens={p.tokens_used} symbols={len(p.symbols)} edges={valid_edges}"
+    if p.pack_root:
+        header += f" pack_root={p.pack_root}"
+    parts.append(header)
+
     # Group symbols by distance.
     groups = _group_by_distance(p.symbols)
     group_names = ["targets", "related", "extended"]
@@ -58,7 +64,7 @@ def encode(p: Payload) -> str:
             if e.status and e.status != "unchanged":
                 line += f" {e.status}"
             edge_lines.append(line)
-        parts.append("## edges")
+        parts.append(f"## edges [{len(edge_lines)}]")
         parts.extend(edge_lines)
 
     return "\n".join(parts) + "\n"

src/gcf/session.py

@@ -77,20 +77,26 @@ def encode_with_session(p: Payload, sess: Session | None = None) -> str:
 
     parts: list[str] = []
 
+    # Build local ID mapping for this response.
+    local_index: dict[str, int] = {}
+    for i, s in enumerate(p.symbols):
+        local_index[s.qualified_name] = i
+
+    # Count valid edges.
+    valid_edges = sum(
+        1 for e in p.edges
+        if e.source in local_index and e.target in local_index
+    )
+
     # Header with session=true marker.
     header = (
         f"GCF tool={p.tool} budget={p.token_budget} tokens={p.tokens_used} "
-        f"symbols={len(p.symbols)} session=true"
+        f"symbols={len(p.symbols)} edges={valid_edges} session=true"
     )
     if p.pack_root:
         header += f" pack_root={p.pack_root}"
     parts.append(header)
 
-    # Build local ID mapping for this response.
-    local_index: dict[str, int] = {}
-    for i, s in enumerate(p.symbols):
-        local_index[s.qualified_name] = i
-
     # Track which symbols are new (need full declaration).
     new_symbols: list[Symbol] = []
 
@@ -122,7 +128,7 @@ def encode_with_session(p: Payload, sess: Session | None = None) -> str:
 
     # Edges section.
     if p.edges:
-        parts.append("## edges")
+        parts.append(f"## edges [{valid_edges}]")
         for e in p.edges:
             src_idx = local_index.get(e.source)
             tgt_idx = local_index.get(e.target)

tests/test_decode.py

@@ -13,7 +13,7 @@ def test_decode_basic_payload():
         "@0 fn pkg.AuthMiddleware 0.78 lsp_resolved\n"
         "## related\n"
         "@1 fn pkg.NewServer 0.54 lsp_resolved\n"
-        "## edges\n"
+        "## edges [1]\n"
         "@0<@1 calls\n"
     )
 
@@ -93,7 +93,7 @@ def test_decode_edge_with_status():
         "## targets\n"
         "@0 fn a.A 0.90 x\n"
         "@1 fn b.B 0.80 x\n"
-        "## edges\n"
+        "## edges [1]\n"
         "@0<@1 calls added\n"
     )
     p = decode(input_text)
@@ -171,7 +171,7 @@ def test_decode_edge_missing_separator():
         "## targets\n"
         "@0 fn a.A 0.90 x\n"
         "@1 fn b.B 0.80 x\n"
-        "## edges\n"
+        "## edges [1]\n"
         "@0@1 calls\n"
     )
     with pytest.raises(DecodeError, match="missing '<' separator"):
@@ -184,7 +184,7 @@ def test_decode_edge_unknown_symbol():
         "GCF tool=test budget=100 tokens=50 symbols=1\n"
         "## targets\n"
         "@0 fn a.A 0.90 x\n"
-        "## edges\n"
+        "## edges [1]\n"
         "@0<@99 calls\n"
     )
     with pytest.raises(DecodeError, match="unknown symbol id"):

tests/test_encode.py

@@ -32,12 +32,12 @@ def test_encode_basic_payload():
 
     output = encode(p)
     expected = (
-        "GCF tool=context_for_task budget=5000 tokens=1847 symbols=2\n"
+        "GCF tool=context_for_task budget=5000 tokens=1847 symbols=2 edges=1\n"
         "## targets\n"
         "@0 fn pkg.AuthMiddleware 0.78 lsp_resolved\n"
         "## related\n"
         "@1 fn pkg.NewServer 0.54 lsp_resolved\n"
-        "## edges\n"
+        "## edges [1]\n"
         "@0<@1 calls\n"
     )
     assert output == expected
@@ -175,13 +175,14 @@ def test_encode_skips_edges_with_missing_symbols():
     )
     output = encode(p)
     # Section header is emitted (matches Go), but no edge lines beneath it
-    assert "## edges" in output
-    lines_after_edges = output.split("## edges\n")[1]
+    assert "## edges [0]" in output
+    assert "edges=0" in output
+    lines_after_edges = output.split("## edges [0]\n")[1]
     assert lines_after_edges.strip() == ""
 
 
 def test_encode_empty_payload():
     """Empty payload produces only header."""
     p = Payload(tool="test", token_budget=100, tokens_used=0)
     output = encode(p)
-    assert output == "GCF tool=test budget=100 tokens=0 symbols=0\n"
+    assert output == "GCF tool=test budget=100 tokens=0 symbols=0 edges=0\n"