feat(ha-config-bootstrap): implement xce_retry_config_t and xce_request_with_retry (tasks 10.1, 10.2)

src/include/request.h

@@ -125,4 +125,43 @@ extern int xce_upgrade_config_req_extract_raw(const uint8_t *pkt_data,
                                                size_t   *out_len,
                                                uint8_t **out_sha256);
 
+/* ── Task 10.2: Client-Side Transparent Retry (Req 7.1–7.6) ─────────────────
+ *
+ * xce_retry_config_t: configurable retry parameters with safe production defaults.
+ * Pass NULL to xce_request_with_retry() to use defaults.
+ */
+typedef struct {
+    int    max_retries;         /* default 20 */
+    int    initial_retry_ms;    /* default 50 */
+    int    max_retry_ms;        /* default 5000 */
+    double backoff_multiplier;  /* default 2.0 (exponential) */
+} xce_retry_config_t;
+
+extern const xce_retry_config_t XCE_RETRY_DEFAULTS;
+
+/*
+ * xce_request_with_retry: transparent retry wrapper for transient controller errors.
+ *
+ * - XCE_ERR_NOT_READY  → backoff, retry same endpoint (Req 7.1)
+ * - XCE_ERR_STANDBY with redirect_host/port → reconnect, retry (Req 7.2)
+ * - XCE_ERR_STANDBY without redirect → backoff, retry (Req 7.2 fallback)
+ * - ECONNREFUSED / ETIMEDOUT → reconnect, retry (Req 7.3)
+ * - EPERM / EINVAL / ENOENT / EACCES → surface immediately (Req 7.4)
+ * - Exhausted max_retries → surface last error (Req 7.5)
+ * - Backoff jitter via rand_r() to prevent thundering herd (Req 7.6)
+ *
+ * NULL cfg → uses XCE_RETRY_DEFAULTS.
+ */
+extern int xce_request_with_retry(endpoint_t *ep,
+                                   xce_request_t *req,
+                                   const xce_retry_config_t *cfg);
+
+/*
+ * xce_retry_send_hook: test-only injection point for the send+receive round-trip.
+ * When non-NULL, xce_request_with_retry() calls this instead of the real network path.
+ * Returns 0 on success (reply_out populated), -errno on transport failure.
+ */
+extern int (*xce_retry_send_hook)(endpoint_t *ep, xce_request_t *req,
+                                   xce_reply_t *reply_out);
+
 #endif