feat: add agent loop and context builder

Agent loop runs on Core 1: pops inbound messages, builds system
prompt from bootstrap files + memory, calls Claude API, saves
session, pushes response to outbound queue. PSRAM-allocated buffers.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

main/agent/agent_loop.c

@@ -0,0 +1,99 @@
+#include "agent_loop.h"
+#include "agent/context_builder.h"
+#include "mimi_config.h"
+#include "bus/message_bus.h"
+#include "llm/llm_proxy.h"
+#include "memory/session_mgr.h"
+
+#include <string.h>
+#include <stdlib.h>
+#include "esp_log.h"
+#include "esp_heap_caps.h"
+
+static const char *TAG = "agent";
+
+static void agent_loop_task(void *arg)
+{
+    ESP_LOGI(TAG, "Agent loop started on core %d", xPortGetCoreID());
+
+    /* Allocate large buffers from PSRAM */
+    char *system_prompt = heap_caps_calloc(1, MIMI_CONTEXT_BUF_SIZE, MALLOC_CAP_SPIRAM);
+    char *messages_json = heap_caps_calloc(1, MIMI_LLM_STREAM_BUF_SIZE, MALLOC_CAP_SPIRAM);
+    char *history_json = heap_caps_calloc(1, MIMI_LLM_STREAM_BUF_SIZE, MALLOC_CAP_SPIRAM);
+    char *response_buf = heap_caps_calloc(1, MIMI_LLM_STREAM_BUF_SIZE, MALLOC_CAP_SPIRAM);
+
+    if (!system_prompt || !messages_json || !history_json || !response_buf) {
+        ESP_LOGE(TAG, "Failed to allocate PSRAM buffers");
+        vTaskDelete(NULL);
+        return;
+    }
+
+    while (1) {
+        mimi_msg_t msg;
+        esp_err_t err = message_bus_pop_inbound(&msg, UINT32_MAX);
+        if (err != ESP_OK) continue;
+
+        ESP_LOGI(TAG, "Processing message from %s:%s", msg.channel, msg.chat_id);
+
+        /* 1. Build system prompt */
+        context_build_system_prompt(system_prompt, MIMI_CONTEXT_BUF_SIZE);
+
+        /* 2. Load session history */
+        session_get_history_json(msg.chat_id, history_json,
+                                 MIMI_LLM_STREAM_BUF_SIZE, MIMI_AGENT_MAX_HISTORY);
+
+        /* 3. Build messages array (history + current message) */
+        context_build_messages(history_json, msg.content,
+                               messages_json, MIMI_LLM_STREAM_BUF_SIZE);
+
+        /* 4. Call Claude API */
+        err = llm_chat(system_prompt, messages_json, response_buf, MIMI_LLM_STREAM_BUF_SIZE);
+
+        if (err == ESP_OK && response_buf[0]) {
+            /* 5. Save to session */
+            session_append(msg.chat_id, "user", msg.content);
+            session_append(msg.chat_id, "assistant", response_buf);
+
+            /* 6. Push response to outbound */
+            mimi_msg_t out = {0};
+            strncpy(out.channel, msg.channel, sizeof(out.channel) - 1);
+            strncpy(out.chat_id, msg.chat_id, sizeof(out.chat_id) - 1);
+            out.content = strdup(response_buf);
+            if (out.content) {
+                message_bus_push_outbound(&out);
+            }
+        } else {
+            /* Send error response */
+            mimi_msg_t out = {0};
+            strncpy(out.channel, msg.channel, sizeof(out.channel) - 1);
+            strncpy(out.chat_id, msg.chat_id, sizeof(out.chat_id) - 1);
+            out.content = strdup(response_buf[0] ? response_buf : "Sorry, I encountered an error.");
+            if (out.content) {
+                message_bus_push_outbound(&out);
+            }
+        }
+
+        /* Free inbound message content */
+        free(msg.content);
+
+        /* Log memory status */
+        ESP_LOGI(TAG, "Free PSRAM: %d bytes",
+                 (int)heap_caps_get_free_size(MALLOC_CAP_SPIRAM));
+    }
+}
+
+esp_err_t agent_loop_init(void)
+{
+    ESP_LOGI(TAG, "Agent loop initialized");
+    return ESP_OK;
+}
+
+esp_err_t agent_loop_start(void)
+{
+    BaseType_t ret = xTaskCreatePinnedToCore(
+        agent_loop_task, "agent_loop",
+        MIMI_AGENT_STACK, NULL,
+        MIMI_AGENT_PRIO, NULL, MIMI_AGENT_CORE);
+
+    return (ret == pdPASS) ? ESP_OK : ESP_FAIL;
+}

main/agent/agent_loop.h

@@ -0,0 +1,14 @@
+#pragma once
+
+#include "esp_err.h"
+
+/**
+ * Initialize the agent loop.
+ */
+esp_err_t agent_loop_init(void);
+
+/**
+ * Start the agent loop task (runs on Core 1).
+ * Consumes from inbound queue, calls Claude API, pushes to outbound queue.
+ */
+esp_err_t agent_loop_start(void);

main/agent/context_builder.c

@@ -0,0 +1,97 @@
+#include "context_builder.h"
+#include "mimi_config.h"
+#include "memory/memory_store.h"
+
+#include <stdio.h>
+#include <string.h>
+#include <time.h>
+#include "esp_log.h"
+#include "cJSON.h"
+
+static const char *TAG = "context";
+
+static size_t append_file(char *buf, size_t size, size_t offset, const char *path, const char *header)
+{
+    FILE *f = fopen(path, "r");
+    if (!f) return offset;
+
+    if (header && offset < size - 1) {
+        offset += snprintf(buf + offset, size - offset, "\n## %s\n\n", header);
+    }
+
+    size_t n = fread(buf + offset, 1, size - offset - 1, f);
+    offset += n;
+    buf[offset] = '\0';
+    fclose(f);
+    return offset;
+}
+
+esp_err_t context_build_system_prompt(char *buf, size_t size)
+{
+    size_t off = 0;
+
+    /* Identity header */
+    time_t now;
+    time(&now);
+    struct tm tm;
+    localtime_r(&now, &tm);
+    char time_str[64];
+    strftime(time_str, sizeof(time_str), "%Y-%m-%d %H:%M (%A)", &tm);
+
+    off += snprintf(buf + off, size - off,
+        "# MimiClaw\n\n"
+        "You are MimiClaw, a personal AI assistant running on an ESP32-S3 device.\n"
+        "You communicate through Telegram and WebSocket.\n\n"
+        "## Current Time\n%s\n\n"
+        "Be helpful, accurate, and concise.\n",
+        time_str);
+
+    /* Bootstrap files */
+    off = append_file(buf, size, off, MIMI_SOUL_FILE, "Personality");
+    off = append_file(buf, size, off, MIMI_USER_FILE, "User Info");
+
+    /* Long-term memory */
+    char mem_buf[4096];
+    if (memory_read_long_term(mem_buf, sizeof(mem_buf)) == ESP_OK && mem_buf[0]) {
+        off += snprintf(buf + off, size - off, "\n## Long-term Memory\n\n%s\n", mem_buf);
+    }
+
+    /* Recent daily notes (last 3 days) */
+    char recent_buf[4096];
+    if (memory_read_recent(recent_buf, sizeof(recent_buf), 3) == ESP_OK && recent_buf[0]) {
+        off += snprintf(buf + off, size - off, "\n## Recent Notes\n\n%s\n", recent_buf);
+    }
+
+    ESP_LOGI(TAG, "System prompt built: %d bytes", (int)off);
+    return ESP_OK;
+}
+
+esp_err_t context_build_messages(const char *history_json, const char *user_message,
+                                 char *buf, size_t size)
+{
+    /* Parse existing history */
+    cJSON *history = cJSON_Parse(history_json);
+    if (!history) {
+        history = cJSON_CreateArray();
+    }
+
+    /* Append current user message */
+    cJSON *user_msg = cJSON_CreateObject();
+    cJSON_AddStringToObject(user_msg, "role", "user");
+    cJSON_AddStringToObject(user_msg, "content", user_message);
+    cJSON_AddItemToArray(history, user_msg);
+
+    /* Serialize */
+    char *json_str = cJSON_PrintUnformatted(history);
+    cJSON_Delete(history);
+
+    if (json_str) {
+        strncpy(buf, json_str, size - 1);
+        buf[size - 1] = '\0';
+        free(json_str);
+    } else {
+        snprintf(buf, size, "[{\"role\":\"user\",\"content\":\"%s\"}]", user_message);
+    }
+
+    return ESP_OK;
+}

main/agent/context_builder.h

@@ -0,0 +1,25 @@
+#pragma once
+
+#include "esp_err.h"
+#include <stddef.h>
+
+/**
+ * Build the system prompt from bootstrap files (SOUL.md, USER.md)
+ * and memory context (MEMORY.md + recent daily notes).
+ *
+ * @param buf   Output buffer (caller allocates, recommend MIMI_CONTEXT_BUF_SIZE)
+ * @param size  Buffer size
+ */
+esp_err_t context_build_system_prompt(char *buf, size_t size);
+
+/**
+ * Build the complete messages JSON array for LLM call.
+ * Combines session history + current user message.
+ *
+ * @param history_json    JSON array from session_get_history_json()
+ * @param user_message    Current user message text
+ * @param buf             Output buffer
+ * @param size            Buffer size
+ */
+esp_err_t context_build_messages(const char *history_json, const char *user_message,
+                                 char *buf, size_t size);