diff --git a/broker.lua b/broker.lua
index a3e9e96..2527200 100644
--- a/broker.lua
+++ b/broker.lua
@@ -229,4 +229,58 @@ function M.chat(model_cfg, messages, opts)
     return table.concat(parts), captured_usage
 end
 
+-- ---------------------------------------------------------------- token_count (Phase 8)
+-- Returns an accurate token count by hitting <endpoint>/tokenize when
+-- the endpoint supports it; falls back to the Phase 0 §8 char/4
+-- heuristic otherwise. Per-endpoint capability cache (session-local;
+-- key per R6 is endpoint-only since B1 confirms /tokenize ignores the
+-- model field on the observed broker).
+--
+-- Never errors. Returns a non-negative integer.
+-- 2s timeout per call so a misbehaving endpoint can't stall the
+-- caller; first miss caches as unsupported for the session.
+local _tokenize_capable = {}    -- [endpoint] = true | false (nil = unprobed)
+
+function M.token_count(model_cfg, text)
+    text = text or ""
+    if text == "" then return 0 end
+    if not (model_cfg and model_cfg.endpoint) then
+        return math.floor(#text / 4)
+    end
+    local ep  = model_cfg.endpoint
+    local cap = _tokenize_capable[ep]
+    if cap == false then
+        return math.floor(#text / 4)
+    end
+    local url = ep:gsub("/+$", "") .. "/tokenize"
+    local body = json.encode({ content = text, model = model_cfg.model })
+    local out, status = curl.post(url, body,
+        { "Content-Type: application/json" },
+        2000)  -- 2s timeout per R5 risk row
+    if not (status == 200 and out) then
+        _tokenize_capable[ep] = false
+        return math.floor(#text / 4)
+    end
+    local doc = json.decode(out)
+    local toks = doc and doc.tokens
+    if type(toks) ~= "table" then
+        _tokenize_capable[ep] = false
+        return math.floor(#text / 4)
+    end
+    _tokenize_capable[ep] = true
+    return #toks
+end
+
+-- Introspection: nil if endpoint un-probed; true/false for the cached
+-- capability. Used by tests and future :tokenize debug meta.
+function M.tokenize_supported(model_cfg)
+    if not (model_cfg and model_cfg.endpoint) then return nil end
+    return _tokenize_capable[model_cfg.endpoint]
+end
+
+-- Test hook: reset the cache between LuaJIT-VM-shared test runs.
+function M._reset_tokenize_cache()
+    _tokenize_capable = {}
+end
+
 return M