core/tools: embed truncate tokens in fetch (offset param)

src/plyngent/tools/net/fetch.py

@@ -16,6 +16,7 @@ from plyngent.tools.net.policy import (
     parse_fetch_url,
     soft_confirm_reason,
 )
+from plyngent.tools.truncate_token import truncate_with_token
 
 
 def format_fetch_result(
@@ -32,13 +33,20 @@ def format_fetch_result(
     warnings: list[str],
     body_kind: str,
     max_chars: int,
+    offset: int = 0,
 ) -> str:
-    text = body_text
+    start = max(0, offset)
-    char_truncated = False
+    body = body_text[start:]
-    if max_chars >= 1 and len(text) > max_chars:
+    body, token = truncate_with_token(
-        omitted = len(text) - max_chars
+        body,
-        text = text[:max_chars] + f"\n...[truncated {omitted} characters]"
+        max_chars,
-        char_truncated = True
+        kind="http",
+        location=final_url,
+        offset=start,
+        limit=max_chars,
+        total_len=len(body_text),
+    )
+    char_truncated = token is not None
     warn_line = "; ".join(warnings) if warnings else ""
     parts = [
         f"status={status}",
@@ -54,7 +62,7 @@ def format_fetch_result(
     if warn_line:
         parts.append(f"warnings={warn_line}")
     parts.append("--- body ---")
-    parts.append(text)
+    parts.append(body)
     return "\n".join(parts)
 
 
@@ -72,6 +80,7 @@ async def fetch(
     max_redirects: int = DEFAULT_MAX_REDIRECTS,
     follow_redirects: bool = True,
     allow_http_downgrade: bool = False,
+    offset: int = 0,
 ) -> str:
     """HTTP request (GET/POST/PUT/DELETE); return status, metadata, and truncated body.
 
@@ -122,6 +131,7 @@ async def fetch(
         warnings=result.warnings,
         body_kind=result.body_kind,
         max_chars=max_chars,
+        offset=offset,
     )
 
 

tests/test_tools/test_fetch.py

@@ -20,6 +20,7 @@ from plyngent.tools.net.policy import (
     parse_fetch_url,
     soft_confirm_reason,
 )
+from plyngent.tools.truncate_token import decode_truncate_token
 from tests.test_tools.helpers import call_async
 
 if TYPE_CHECKING:
@@ -237,6 +238,36 @@ async def test_fetch_truncation_and_binary(workspace: Path, http_server: str) ->
     assert "binary body omitted" in out_bin
 
 
+async def test_fetch_char_truncation_embeds_token(workspace: Path, http_server: str) -> None:
+    del workspace
+    port = int(http_server.rsplit(":", 1)[1])
+    grant_private_host("127.0.0.1", port)
+
+    out = await call_async(fetch, f"{http_server}/big", max_chars=1000)
+    assert "truncated=true" in out
+    body = out.split("--- body ---", 1)[-1]
+    assert "TRUNCATE_TOKEN:" in body
+    token_line = next(ln for ln in body.splitlines() if "TRUNCATE_TOKEN:" in ln)
+    token_str = token_line.split("[TRUNCATE_TOKEN: ", 1)[1].rstrip("]")
+    token = decode_truncate_token(token_str)
+    assert token is not None
+    assert token.kind == "http"
+    assert token.offset == 1000  # next chunk starts at max_chars
+    assert token.limit == 1000
+
+
+async def test_fetch_offset_skips_body(workspace: Path, http_server: str) -> None:
+    del workspace
+    port = int(http_server.rsplit(":", 1)[1])
+    grant_private_host("127.0.0.1", port)
+
+    # /big body is 5000 chars; offset 4900 leaves 100 chars, no token needed.
+    out = await call_async(fetch, f"{http_server}/big", max_chars=200, offset=4900)
+    body = out.split("--- body ---", 1)[-1]
+    assert body.strip() == "x" * 100
+    assert "TRUNCATE_TOKEN:" not in out
+
+
 async def test_fetch_private_denied_without_grant(workspace: Path, http_server: str) -> None:
     del workspace
     # No grant, no policy hook → hard deny (even though server is up).