Problem

Issue #7 抽 parseGetChatHistoryArgs pure function 重構了 get_chat_history handler，但 dump_chat_to_markdown handler (Server.swift:466-499) 保留同樣的 inline 驗證邏輯：

• chat_id guard
• max_messages 0/10_000 cap (一字不差)
• parseISODate + parseUntilDate with DateParseError catch
• errorResult 轉換

From verification of #7 by devils-advocate (HIGH):
「若未來改 HandlerArgs.swift 的 cap policy，dump_chat_to_markdown 會 silently drift。commit message 和 code comment 都沒提這 exception，test file 名稱 ServerHandlerLogicTests 又泛化，下個 reviewer 容易誤以為『all handlers covered』」

Type

refactor

Expected

• 抽 DumpChatToMarkdownArgs struct + parseDumpChatToMarkdownArgs(_ args:) throws -> ... pure function
• 或 generalize: parseGetChatHistoryArgs → parseChatHistoryArgs（帶 isDumpMode: Bool 或 output context），兩個 handler 共用
• 對應 unit tests 覆蓋 dump_chat_to_markdown 的 validation 路徑

Code Reference

• Sources/CheTelegramAllMCPCore/Server.swift:466-499（被忽略的 handler）
• Sources/CheTelegramAllMCPCore/HandlerArgs.swift（可 extend 的模組）

Related: #7

Current Status

Phase: closed
Last updated: 2026-04-26 by idd-close

Key Decisions

• 採 Option A（parallel struct + parser）拒絕 Option B（god function with isDumpMode）
• 額外抽 validateMaxMessagesCap shared helper：兩個 parser 共用 0/10_000 cap invariant
• Two-phase commit strategy：Phase 1 prerequisite extract、Phase 2 dump parser + tests
• Direct-commit path（一致於 get_chat_history: from_message_id=0 首次呼叫只回傳 1 則訊息 #3-MCP 層補 handler 行為 unit test（get_chat_history） #7、Test hardening: int64 helper DRY + boundary + TZ assertions #15）
• 6-AI verify: 5 PASS + 1 in-scope DA fix（CHANGELOG 10 → 11）+ 4 follow-ups + 2 won't-fix（理由透明）

Scope Changes

• 增補：testDumpExplicitSelfLabel（scope+1，default vs explicit override 對稱覆蓋，已透明標註）
• 增補：CHANGELOG 10 new tests → 11 new tests in-scope fix（commit ac306ba）

Blocking

(none)

Follow-up

• Catch chain integration tests for handler error wiring (#7/#13 follow-up) #18 — Catch chain integration tests for handler error wiring（DA MEDIUM）
• TZ symmetric mutation guard for testUntilDateUsesEndOfDay (parity with #16) #19 — TZ symmetric mutation guard parity（fold into Test design: fixed-TZ assertion to catch symmetric TZ mutations #16 family）
• max_messages silently falls back to default for .string/.double values (cap bypass) #20 — max_messages .string/.double silently bypass cap（pre-existing parity bug）
• output_path traversal hardening for dump_chat_to_markdown #21 — output_path traversal hardening（pre-existing security MEDIUM）

Test counts

• 139 → 150 (+11), 0 failures
• Codex 獨立驗證 24 tests pass

Commits

• a834e88 refactor: extract validateMaxMessagesCap shared helper (Refactor dump_chat_to_markdown handler to use parseGetChatHistoryArgs pattern #13)
• f4ea946 refactor: extract parseDumpChatToMarkdownArgs pure function (Refactor dump_chat_to_markdown handler to use parseGetChatHistoryArgs pattern #13)
• ac306ba docs: fix CHANGELOG test count 10 → 11 (Refactor dump_chat_to_markdown handler to use parseGetChatHistoryArgs pattern #13)