feat(session): Step 4.A — remove the GENAI:/LLM: query-prefix escape hatches

Per decision Q2 in the GenAI plugin carve-out design doc, the in-line
MySQL-protocol prefixes that bypassed routing, ACLs, and the query
processor are removed.  Users reach GenAI features through MCP, admin
SQL, or the REST endpoint -- as the rest of the carve-out finishes,
nothing else needs the in-core GENAI:/LLM: handlers.

Removals:

  lib/MySQL_Session.cpp (-933 lines)
    - handler___status_WAITING_CLIENT_DATA___STATE_SLEEP___MYSQL_COM_QUERY___genai
    - handler___status_WAITING_CLIENT_DATA___STATE_SLEEP___MYSQL_COM_QUERY___llm
    - handler___status_WAITING_CLIENT_DATA___STATE_SLEEP___genai_send_async
    - handler___status_WAITING_CLIENT_DATA___STATE_SLEEP___handle_genai_response
    - genai_cleanup_request
    - check_genai_events
    - The COM_QUERY prefix-detection block that dispatched to those
      handlers
    - The check_genai_events poll-loop hook in WAITING_CLIENT_DATA

  include/MySQL_Session.h (-67 lines)
    - All matching method declarations, with their doxygen

  include/Base_Session.h (-15 lines)
    - GenAI_PendingRequest struct
    - pending_genai_requests_ map
    - next_genai_request_id_ counter
    - genai_epoll_fd_ per-session epoll fd

  lib/Base_Session.cpp (-9 lines)
    - The init block that created the per-session genai_epoll_fd_

LLM: was deleted alongside GENAI: even though only GENAI: is named in
the design.  They share the same `#ifdef PROXYSQLGENAI` gate, the same
async-genai socketpair plumbing, and the same rationale.  Leaving LLM:
behind would have left a half-block referencing functions that no
longer exist; if we want LLM: back later the plugin can re-implement
it (or a more general request-multiplexer ABI extension can land).

The async-genai socketpair protocol (GenAI_RequestHeader /
GenAI_ResponseHeader, defined in include/GenAI_Thread.h) is now
unreferenced from outside lib/GenAI_Thread.cpp itself; those structs
disappear when GenAI_Thread moves to plugins/genai/ in Step 5.

Verified:
  - clean rebuild of libproxysql.a + proxysql + ProxySQL_GenAI_Plugin.so
  - all 60 unit-test binaries pass
  - smoke test: daemon starts, SELECT through admin works, SIGTERM
    shuts down cleanly

Net diff: -1010 / +28 lines.  Largest deletion of the carve-out so far.

Author: renecannao

include/Base_Session.h

@@ -99,20 +99,10 @@ class Base_Session {
 	//MySQL_STMTs_meta *sess_STMTs_meta;
 	//StmtLongDataHandler *SLDH;
 
-	// GenAI async support
-#ifdef epoll_create1
-	struct GenAI_PendingRequest {
-		uint64_t request_id;
-		int client_fd;  // MySQL side of socketpair
-		std::string json_query;
-		std::chrono::steady_clock::time_point start_time;
-		PtrSize_t *original_pkt;  // Original packet to complete
-	};
-
-	std::unordered_map<uint64_t, GenAI_PendingRequest> pending_genai_requests_;
-	uint64_t next_genai_request_id_;
-	int genai_epoll_fd_;  // For monitoring GenAI response fds
-#endif
+	// GenAI async support (per-session epoll fd + pending-request map)
+	// removed in Step 4 of the GenAI plugin carve-out -- the
+	// GENAI:/LLM: prefix handlers that owned this state are gone.
+	// See decision Q2 in the design doc.
 
 
 

include/MySQL_Session.h

@@ -304,74 +304,15 @@ class MySQL_Session: public Base_Session<MySQL_Session, MySQL_Data_Stream, MySQL
 	void handler_rc0_RefreshActiveTransactions(MySQL_Connection* myconn);
 	void handler___status_WAITING_CLIENT_DATA___STATE_SLEEP___MYSQL_COM_INIT_DB_replace_CLICKHOUSE(PtrSize_t& pkt);
 	void handler___status_WAITING_CLIENT_DATA___STATE_SLEEP___MYSQL_COM_QUERY___not_mysql(PtrSize_t& pkt);
-	void handler___status_WAITING_CLIENT_DATA___STATE_SLEEP___MYSQL_COM_QUERY___genai(const char* query, size_t query_len, PtrSize_t* pkt);
-	void handler___status_WAITING_CLIENT_DATA___STATE_SLEEP___MYSQL_COM_QUERY___llm(const char* query, size_t query_len, PtrSize_t* pkt);
-#ifdef epoll_create1
-	/**
-	 * @brief Handle GenAI response from socketpair
-	 *
-	 * Called when epoll notifies that a GenAI response is available on a client fd.
-	 * Reads the GenAI_ResponseHeader and JSON result, then sends the resultset
-	 * to the MySQL client.
-	 *
-	 * @param fd The socketpair fd (MySQL side) with data available to read
-	 *
-	 * @see handler___status_WAITING_CLIENT_DATA___STATE_SLEEP___genai_send_async()
-	 * @see check_genai_events()
-	 */
-	void handler___status_WAITING_CLIENT_DATA___STATE_SLEEP___handle_genai_response(int fd);
+	// MYSQL_COM_QUERY___genai / MYSQL_COM_QUERY___llm and the entire
+	// async-genai socketpair infrastructure (handle_genai_response,
+	// genai_send_async, genai_cleanup_request, check_genai_events) were
+	// removed in Step 4 of the GenAI plugin carve-out (decision Q2 in
+	// the design doc).  GenAI now reaches clients through MCP / admin
+	// SQL / REST -- the in-line MySQL-protocol "GENAI:" / "LLM:"
+	// prefix escape hatches were a debug/POC convenience that bypassed
+	// routing, ACLs, and the query processor.
 
-	/**
-	 * @brief Send GenAI request asynchronously via socketpair
-	 *
-	 * Creates a socketpair for async communication with the GenAI module:
-	 * 1. Creates socketpair(fds)
-	 * 2. Registers fds[1] with GenAI module
-	 * 3. Sends GenAI_RequestHeader + JSON query via fds[0]
-	 * 4. Adds fds[0] to session's epoll for response notification
-	 * 5. Returns immediately (MySQL thread is free to process other queries)
-	 *
-	 * The response will be handled by handle_genai_response() when ready.
-	 *
-	 * @param query The JSON query string (after "GENAI:" prefix)
-	 * @param query_len Length of the query string
-	 * @param pkt Original packet (stored for later cleanup)
-	 * @return true if request was sent successfully, false on error
-	 *
-	 * @see handler___status_WAITING_CLIENT_DATA___STATE_SLEEP___handle_genai_response()
-	 */
-	bool handler___status_WAITING_CLIENT_DATA___STATE_SLEEP___genai_send_async(const char* query, size_t query_len, PtrSize_t* pkt);
-
-	/**
-	 * @brief Cleanup a GenAI pending request
-	 *
-	 * Removes the request from the pending map, closes the socketpair fd,
-	 * removes from epoll, and frees the original packet. Called after
-	 * the response is processed or on error.
-	 *
-	 * @param request_id The request ID to clean up
-	 *
-	 * @see handler___status_WAITING_CLIENT_DATA___STATE_SLEEP___genai_send_async()
-	 */
-	void genai_cleanup_request(uint64_t request_id);
-
-	/**
-	 * @brief Check for pending GenAI responses
-	 *
-	 * Performs a non-blocking epoll_wait on the session's GenAI epoll fd
-	 * to check if any responses are ready. If a response is found, it's
-	 * processed immediately by calling handle_genai_response().
-	 *
-	 * This is called from the main handler() loop in the WAITING_CLIENT_DATA
-	 * case to ensure GenAI responses are processed promptly even when
-	 * there's no new client data.
-	 *
-	 * @return true if a response was processed, false if no responses were ready
-	 *
-	 * @see handler___status_WAITING_CLIENT_DATA___STATE_SLEEP___handle_genai_response()
-	 */
-	bool check_genai_events();
-#endif
 	bool handler___status_WAITING_CLIENT_DATA___STATE_SLEEP___MYSQL_COM_QUERY_detect_SQLi();
 	bool handler___status_WAITING_CLIENT_DATA___STATE_SLEEP_MULTI_PACKET(PtrSize_t& pkt);
 	bool handler___status_WAITING_CLIENT_DATA___STATE_SLEEP___MYSQL_COM__various(PtrSize_t* pkt, bool* wrong_pass);

lib/Base_Session.cpp

@@ -86,15 +86,9 @@ void Base_Session<S,DS,B,T>::init() {
 		MySQL_Session* mysession = static_cast<S*>(this);
 		mysession->sess_STMTs_meta = new MySQL_STMTs_meta();
 		mysession->SLDH = new StmtLongDataHandler();
-#ifdef epoll_create1
-		// Initialize GenAI async support
-		mysession->next_genai_request_id_ = 1;
-		mysession->genai_epoll_fd_ = epoll_create1(EPOLL_CLOEXEC);
-		if (mysession->genai_epoll_fd_ < 0) {
-			proxy_error("Failed to create GenAI epoll fd: %s\n", strerror(errno));
-			mysession->genai_epoll_fd_ = -1;
-		}
-#endif
+		// GenAI async epoll-fd init removed in Step 4 of the GenAI
+		// plugin carve-out (Base_Session.h GenAI async members are
+		// gone with the GENAI:/LLM: prefix handlers).
 	}
 };