fix(adapters): sanitize tool-call ids so one bad upstream can't kill every Claude slot

Anthropic requires tool_use.id / tool_result.tool_use_id to match
^[a-zA-Z0-9_-]{1,64}$ and rejects the WHOLE request otherwise with
REQUEST_BODY_INVALID / "Invalid tool use format". OpenAI has no such rule, so
an OpenAI-compatible model can mint an id like "bash:0"
(xinjianya/moonshotai/kimi-k3 does exactly that).

In a fan-out router that id does not stay local: the client stores it in its
history and replays it to every other source. One such id therefore kills
every Claude slot at once — justwoker, tabitoken and 扇贝 are all
Claude-behind-{OpenAI,Anthropic} — and an AUTO request falls through all four
tiers to whatever tolerant model is left. Observed live: 4 consecutive 503
"all N auto providers failed" with tier 1/2/3 each reporting the same 400.

Both directions are sanitized, in both adapters:
  - request:  tool_calls[].id and tool_call_id, so poisoned history recovers
  - response: non-streaming tool_calls[].id and the first streamed fragment,
              so a bad id never enters a client session in the first place

safe_tool_id is pure and deterministic, so a call and its result are rewritten
identically within one request. A rewritten id keeps an 8-hex digest of the
original, without which distinct ids could collapse ("a:b" and "a_b") into a
duplicate/unpaired tool_use. Already-legal ids pass through byte-identical, so
well-behaved traffic is unaffected. openai.lua carries its own copy because
Lua adapters have no shared prelude.

Streamed argument fragments carry no id and must stay id-less, otherwise
index-based accumulation on the client breaks; a test pins that.

internal/lua/adapters/anthropic.lua

@@ -14,6 +14,34 @@ local ROLE_WHITELIST = {
     system = true, user = true, assistant = true, tool = true,
 }
 
+-- Anthropic requires tool_use.id / tool_result.tool_use_id to match
+-- ^[a-zA-Z0-9_-]{1,64}$ and rejects the WHOLE request otherwise with
+-- REQUEST_BODY_INVALID / "Invalid tool use format". OpenAI imposes no such
+-- rule, so an OpenAI-compatible upstream can hand a client an id like
+-- "bash:0" (observed from moonshotai/kimi-k3); once that lands in the
+-- client's history, every later replay kills every Claude slot at once and
+-- an AUTO chain falls through all tiers.
+--
+-- safe_tool_id is pure and deterministic, so a tool_use block and its
+-- matching tool_result are rewritten identically within one request. A
+-- rewritten id keeps an 8-hex digest of the ORIGINAL id: without it two
+-- distinct ids could collapse into one ("a:b" and "a_b"), which Anthropic
+-- rejects as a duplicate/unpaired tool_use. Already-legal ids pass through
+-- untouched so upstreams that round-trip their own ids are unaffected.
+local TOOL_ID_MAX = 64
+
+local function safe_tool_id(id)
+    if type(id) ~= "string" or id == "" then return "" end
+    local clean = string.gsub(id, "[^A-Za-z0-9_-]", "_")
+    if clean == id and #clean <= TOOL_ID_MAX then
+        return clean
+    end
+    local digest = string.sub(sha256_hex(id), 1, 8)
+    local keep = TOOL_ID_MAX - #digest - 1
+    if #clean > keep then clean = string.sub(clean, 1, keep) end
+    return clean .. "_" .. digest
+end
+
 local function collect_blocks(content)
     if type(content) == "string" then
         if content == "" then return {} end
@@ -104,7 +132,7 @@ function adapter.transform_request(raw_body)
                         end
                         table.insert(blocks, {
                             type  = "tool_use",
-                            id    = tc.id or "",
+                            id    = safe_tool_id(tc.id),
                             name  = fn.name or "",
                             input = input,
                         })
@@ -119,7 +147,7 @@ function adapter.transform_request(raw_body)
             -- user message with tool_result content blocks.
             table.insert(pending_tool, {
                 type        = "tool_result",
-                tool_use_id = m.tool_call_id or "",
+                tool_use_id = safe_tool_id(m.tool_call_id),
                 content     = text_of(m.content),
             })
 
@@ -242,7 +270,7 @@ function adapter.transform_response(raw_body)
                 unified.reasoning_content = (unified.reasoning_content or "") .. block.thinking
             elseif block.type == "tool_use" then
                 table.insert(tcs, {
-                    id        = block.id or "",
+                    id        = safe_tool_id(block.id),
                     type      = "function",
                     name      = block.name or "",
                     arguments = block.input or {},
@@ -330,7 +358,7 @@ function adapter.transform_stream_chunk(raw_chunk)
                 content = "", done = false,
                 tool_calls = { {
                     index = chunk.index or 0,
-                    id    = cb.id or "",
+                    id    = safe_tool_id(cb.id),
                     type  = "function",
                     ["function"] = { name = cb.name or "", arguments = "" },
                 } },