From fa426c1bcd0ed02079de313c41696d07755f2145 Mon Sep 17 00:00:00 2001
From: vitali87 <eheva87@gmail.com>
Date: Sun, 20 Sep 2026 22:56:49 +0100
Subject: [PATCH] feat: map change-signature call arguments

---
 codebase_rag/editing/signature_calls.py | 136 ++++++++++++++++++++++++
 1 file changed, 136 insertions(+)
 create mode 100644 codebase_rag/editing/signature_calls.py

diff --git a/codebase_rag/editing/signature_calls.py b/codebase_rag/editing/signature_calls.py
new file mode 100644
index 0000000000..8a9e6b2d1a
--- /dev/null
+++ b/codebase_rag/editing/signature_calls.py
@@ -0,0 +1,136 @@
+"""Call-site argument mapping for change_signature."""
+
+from __future__ import annotations
+
+from tree_sitter import Node
+
+from .. import constants as cs
+from .. import graph_query
+from ..parsers.call_processor import _find_call_arguments_node, _split_call_arguments
+from ..types_defs import ResultRow
+from .signature_params import _text
+from .signature_types import ParamSpec
+
+_SPLAT_TYPES = frozenset(
+    {
+        cs.TS_PY_LIST_SPLAT,
+        cs.TS_PY_DICTIONARY_SPLAT,
+        cs.TS_SPREAD_ELEMENT,
+    }
+)
+
+
+def _site_end(row: graph_query.CallSiteRow | ResultRow) -> tuple[int, int] | None:
+    """The site's recorded end point as tree-sitter counts it, if recorded."""
+    end_line, end_col = row.get("end_line"), row.get("end_col")
+    if isinstance(end_line, int) and isinstance(end_col, int):
+        return (end_line - 1, end_col)
+    return None
+
+
+def _call_at(
+    root: Node, line: int, col: int, end: tuple[int, int] | None = None
+) -> Node | None:
+    """The call node at (line, col) that carries arguments.
+
+    With the site's recorded end point the exact call is chosen, so a
+    chained `helper(2).upper()` rewrites `helper`'s arguments and not the
+    outer call's; without it the outermost call at that point is taken.
+    """
+    stack = [root]
+    found: Node | None = None
+    while stack:
+        node = stack.pop()
+        if (
+            node.start_point == (line - 1, col)
+            and _find_call_arguments_node(node) is not None
+        ):
+            if end is not None:
+                if node.end_point == end:
+                    return node
+            elif found is None or node.end_byte > found.end_byte:
+                found = node
+        if node.start_point[0] <= line - 1 <= node.end_point[0]:
+            stack.extend(node.children)
+    return found
+
+
+def _map_arguments(
+    args_node: Node,
+    old_names: list[str],
+    specs: list[ParamSpec],
+    language: cs.SupportedLanguage | None,
+    keyword_only: frozenset[str] = frozenset(),
+) -> list[str] | str:
+    """The site's new argument texts, or the reason it cannot be mapped.
+
+    A keyword naming a keyword-only parameter is not part of the positional
+    mapping and is carried through exactly as written.
+    """
+    positional, keyword = _split_call_arguments(args_node)
+    if any(child.type in _SPLAT_TYPES for child in args_node.named_children):
+        return cs.SIGNATURE_SPLAT
+    values: dict[int, tuple[str, bool]] = {}
+    for index, node in enumerate(positional):
+        values[index] = (_text(node), False)
+    carried: list[str] = []
+    for name, node in keyword.items():
+        if name in keyword_only:
+            carried.append(f"{name}={_text(node)}")
+            continue
+        if name not in old_names:
+            return cs.SIGNATURE_UNKNOWN_KEYWORD.format(name=name)
+        values[old_names.index(name)] = (_text(node), True)
+    keywords_ok = language == cs.SupportedLanguage.PYTHON
+    if not positional and _keywords_already_fit(values, old_names, specs):
+        # A keyword-only site binds by name: reordering would change
+        # nothing but the spelling, so it is left exactly as written.
+        return [_text(child) for child in args_node.named_children]
+    out: list[str] = []
+    keyword_mode = False
+    for spec in specs:
+        if spec.from_index is not None:
+            found = values.pop(spec.from_index, None)
+            if found is None:
+                # The site relied on the old default; every later value
+                # must be spelled by name so positions do not shift.
+                keyword_mode = True
+                continue
+            text, was_keyword = found
+            if was_keyword or keyword_mode:
+                if not keywords_ok:
+                    return cs.SIGNATURE_NEEDS_KEYWORDS
+                out.append(f"{spec.name}={text}")
+                keyword_mode = True
+            else:
+                out.append(text)
+        elif spec.literal is not None:
+            if keyword_mode:
+                if not keywords_ok:
+                    return cs.SIGNATURE_NEEDS_KEYWORDS
+                out.append(f"{spec.name}={spec.literal}")
+            else:
+                out.append(spec.literal)
+        else:
+            return cs.SIGNATURE_UNMAPPED_PARAM.format(name=spec.name)
+    # Every spec consumed what it named; anything still in `values` is an
+    # argument the new signature has no home for. Rewriting would drop it
+    # from the caller's source silently -- and the contract cannot catch
+    # that, because the argument is gone from the file before the delta is
+    # measured, so the `too_many` arity check sees nothing.
+    if values:
+        return cs.SIGNATURE_SURPLUS_ARGS
+    return out + carried
+
+
+def _keywords_already_fit(
+    values: dict[int, tuple[str, bool]], old_names: list[str], specs: list[ParamSpec]
+) -> bool:
+    """Every passed keyword keeps its name and nothing new must be inserted."""
+    kept = {spec.from_index: spec.name for spec in specs if spec.from_index is not None}
+    if any(index not in kept or kept[index] != old_names[index] for index in values):
+        return False
+    return all(spec.from_index is not None for spec in specs)
+
+
+# --- literal type checks --------------------------------------------------------