context: tool turns + tool_calls on assistant; use_tool_role fallback

Phase 2 commit #3 per docs/PHASE2.md §12. Three concrete edits per §3
context.lua row (the BLOCKER-fold-in from review):

  (a) Loosen Context:append shape-per-role: assistant may carry empty
      content if tool_calls is non-empty; role:"tool" requires
      tool_call_id + content.

  (b) Preserve tool_calls / tool_call_id on store (Phase 1 :append
      built {role, content} only and silently dropped extras).

  (c) Extend to_messages() with two emission modes selected by
      use_tool_role:
        true  (default) — OpenAI-standard role:"tool" + assistant
          turns with tool_calls (wrapped as {id, type:"function",
          function:{name, arguments}}).
        false (fallback) — collapse assistant-with-tool_calls + its
          following role:"tool" turns into a single assistant text
          turn with synthesized "[tool: name]\n<args>\n[result]\n
          <content>" body; merge consecutive assistant turns so the
          trailing post-tool-result text doesn't yield asst/asst
          back-to-back (same strict-template gotcha PHASE0.md §6
          warned about for user/user).

Alternation assert added (N4): role:"tool" turns must trace back
through zero-or-more prior tool turns to an assistant-with-tool_calls.
Catches sub-loop bugs at append time. Orphan tool turns rejected.

pending_exec_output behavior unchanged per §3 row: buffer persists
across tool-call sub-loops, flushes on next genuine user turn (B4).

Smoke-tested §12 verify-row #3:
  (i)   default mode round-trip — 5 OpenAI-shape messages, tool_calls
        + tool_call_id preserved.
  (ii)  fallback mode round-trip — collapsed into 3 messages
        (system/user/assistant), tool_calls + role:"tool" not emitted.
  (iii) multi-call: 2 tool_calls in one assistant turn followed by 2
        tool replies, both modes render correctly.
  (iv)  orphan tool turn after user — assertion fires.
  (v)   B4: pending_exec_output survives a tool sub-loop, flushes on
        next :append_user.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
2026-05-12 13:10:47 +00:00
parent 0fde77fe35
commit 7c221a8aae
+141 -7
View File
@@ -1,7 +1,10 @@
-- context.lua — in-memory conversation history + token budget.
-- Phase 0: ordered turn list, sliding-window eviction by max_turns.
-- Tokenization is char/4 heuristic in Phase 0; accurate count is Phase 3 (Q1).
-- See docs/PHASE0.md §6, §8.
-- Phase 2 (added 2026-05-12): support for `role:"tool"` turns and assistant
-- turns carrying `tool_calls = [...]`, plus a `use_tool_role` rendering
-- toggle for the strict-chat-template fallback path (Q18).
-- See docs/PHASE0.md §6, §8 and docs/PHASE2.md §3 / §5.
local M = {}
@@ -25,13 +28,53 @@ function M.new(opts)
pending_exec_output = nil, -- buffered until next user turn (§6)
max_turns = opts.max_turns or 40,
token_budget = opts.token_budget or 4096,
-- Phase 2: tool-role rendering toggle. true = emit OpenAI-standard
-- role:"tool" messages from to_messages(); false = collapse
-- assistant+tool_calls and tool turns into a single assistant text
-- turn for chat templates that reject the role:"tool" shape.
-- Default true per PHASE2.md §12 "Q18 default"; flip from caller.
use_tool_role = (opts.use_tool_role == nil) and true
or opts.use_tool_role,
}, Context)
end
-- Append a turn. Phase 2 widens what's valid:
-- role="user" content (string) required
-- role="system" content (string) required (callers shouldn't add system
-- turns directly; system prompt is stored separately and
-- prepended at to_messages time per §6)
-- role="assistant" content may be empty IF tool_calls is non-empty;
-- otherwise content required
-- role="tool" tool_call_id required + content required; the preceding
-- stored turn must be an assistant turn with non-empty
-- tool_calls (debug assertion catches sub-loop bugs early
-- per PHASE2.md §3 row + N4 in review)
function Context:append(turn)
assert(type(turn) == "table" and turn.role and turn.content,
"context:append requires { role = ..., content = ... }")
self.turns[#self.turns + 1] = { role = turn.role, content = turn.content }
assert(type(turn) == "table" and turn.role,
"context:append requires { role = ... }")
local stored = { role = turn.role, content = turn.content or "" }
if turn.role == "assistant" and turn.tool_calls and #turn.tool_calls > 0 then
stored.tool_calls = turn.tool_calls
elseif turn.role == "tool" then
assert(turn.tool_call_id, "context:append role=tool requires tool_call_id")
assert(turn.content, "context:append role=tool requires content")
-- A tool turn may follow either an assistant-with-tool_calls (the
-- first reply in the sub-loop) or another tool turn (subsequent
-- replies when the assistant emitted multiple parallel tool_calls).
-- Walk back through tool turns until we hit a non-tool; that turn
-- must be an assistant with non-empty tool_calls.
local j = #self.turns
while j > 0 and self.turns[j].role == "tool" do j = j - 1 end
local anchor = self.turns[j]
assert(anchor and anchor.role == "assistant"
and anchor.tool_calls and #anchor.tool_calls > 0,
"context:append role=tool must follow assistant with tool_calls "
.. "(possibly via prior tool turns in the same sub-loop)")
stored.tool_call_id = turn.tool_call_id
else
assert(turn.content, "context:append requires content for role=" .. turn.role)
end
self.turns[#self.turns + 1] = stored
end
-- Buffer captured shell-exec output. Per §6 (post user-test fix), exec output
@@ -58,12 +101,103 @@ function Context:append_user(content)
self:append({ role = "user", content = content })
end
-- Compact JSON-ish rendering used by the fallback (use_tool_role=false) path
-- to convert a tool_calls + tool-result pair into inline text. Not OpenAI-
-- standard — only used when a strict chat template rejects role:"tool".
local function inline_tool_call(call, result_content)
return ("[tool: %s]\n%s\n[result]\n%s")
:format(call.name or "?",
tostring(call.arguments or ""),
tostring(result_content or ""))
end
-- Render the messages array for broker.chat (system prompt prepended; turns
-- in order). The system prompt is NOT stored in self.turns per §6.
-- in order). Phase 2 adds two emission modes:
--
-- use_tool_role = true (default): pass through OpenAI-standard
-- {role:"assistant", content, tool_calls} and {role:"tool", tool_call_id,
-- content} turns unchanged.
--
-- use_tool_role = false (fallback, Q18): collapse each
-- assistant-with-tool_calls + its following role:"tool" turn(s) into a
-- single assistant text turn carrying the synthesized "[tool: name]\n
-- <args>\n[result]\n<content>" body. The role:"tool" turns and the
-- tool_calls field are NOT emitted. Same logical alternation seen by the
-- model (user → assistant → user → assistant), no strict-template breakage.
--
-- The system prompt is NOT stored in self.turns per §6.
function Context:to_messages()
local msgs = { { role = "system", content = self.system_prompt } }
for _, t in ipairs(self.turns) do
msgs[#msgs + 1] = { role = t.role, content = t.content }
if self.use_tool_role then
for _, t in ipairs(self.turns) do
local m = { role = t.role, content = t.content }
if t.role == "assistant" and t.tool_calls then
-- OpenAI shape wraps each call as
-- {id, type:"function", function:{name, arguments}}.
local oai = {}
for i, c in ipairs(t.tool_calls) do
oai[i] = {
id = c.id,
type = "function",
["function"] = { name = c.name,
arguments = c.arguments or "" },
}
end
m.tool_calls = oai
elseif t.role == "tool" then
m.tool_call_id = t.tool_call_id
end
msgs[#msgs + 1] = m
end
return msgs
end
-- Fallback path: walk turns, collapse asst-with-tool_calls + following
-- tool turns into a single asst text turn. Merge consecutive assistant
-- turns afterward so the trailing post-tool-result assistant text
-- doesn't produce asst/asst back-to-back (which strict templates would
-- also reject — same gotcha PHASE0.md §6 warned about for user/user).
local function push_or_merge_assistant(content)
local last = msgs[#msgs]
if last and last.role == "assistant" then
last.content = last.content .. "\n" .. content
else
msgs[#msgs + 1] = { role = "assistant", content = content }
end
end
local i = 1
while i <= #self.turns do
local t = self.turns[i]
if t.role == "assistant" and t.tool_calls then
local parts = {}
if t.content and t.content ~= "" then
parts[#parts + 1] = t.content
end
for ci, call in ipairs(t.tool_calls) do
local result_text = ""
local next_t = self.turns[i + ci]
if next_t and next_t.role == "tool"
and next_t.tool_call_id == call.id then
result_text = next_t.content
end
parts[#parts + 1] = inline_tool_call(call, result_text)
end
push_or_merge_assistant(table.concat(parts, "\n"))
i = i + 1 + #t.tool_calls
elseif t.role == "tool" then
-- Orphan tool turn (no preceding asst-tool_calls captured it).
-- Shouldn't happen given the :append assertion, but defensively
-- drop it rather than emit a malformed message.
i = i + 1
elseif t.role == "assistant" then
push_or_merge_assistant(t.content or "")
i = i + 1
else
msgs[#msgs + 1] = { role = t.role, content = t.content }
i = i + 1
end
end
return msgs
end