feat(log): Read log level from the env

README.md

@@ -443,6 +443,7 @@ codebase-memory-mcp config reset auto_index              # reset to default
 | `CBM_CACHE_DIR` | `~/.cache/codebase-memory-mcp` | Override the database storage directory. All project indexes and config are stored here. |
 | `CBM_DIAGNOSTICS` | `false` | Set to `1` or `true` to enable periodic diagnostics output to `/tmp/cbm-diagnostics-<pid>.json`. |
 | `CBM_DOWNLOAD_URL` | *(GitHub releases)* | Override the download URL for updates. Used for testing or self-hosted deployments. |
+| `CBM_LOG_LEVEL` | `info` | Set the minimum log level. Accepted values (case-insensitive): `debug`, `info`, `warn`, `error`, `none` — or their numeric equivalents `0`–`4` matching the internal enum. Logs go to stderr; stdout is reserved for MCP JSON-RPC. |
 | `CBM_WORKERS` | *(detected)* | Override the parallel-indexing worker count returned by `cbm_default_worker_count`. Useful inside containers where `sysconf(_SC_NPROCESSORS_ONLN)` reports host CPUs rather than the cgroup's effective quota. Range 1–256; invalid values are ignored with a warning. |
 
 ```bash

src/foundation/log.c

@@ -7,10 +7,49 @@
 #include <stdarg.h>
 #include <stdint.h>
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 
 static CBMLogLevel g_log_level = CBM_LOG_INFO;
 static cbm_log_sink_fn g_log_sink = NULL;
 
+void cbm_log_init_from_env(void) {
+    /* Read CBM_LOG_LEVEL — use getenv() directly: this runs before any threads
+     * are created, so there is no concurrent setenv() race to worry about. */
+    const char *val = getenv("CBM_LOG_LEVEL");
+    if (!val || val[0] == '\0') {
+        return;
+    }
+
+    /* Case-insensitive comparison via tolower on first char + strcmp */
+    char lo[16];
+    size_t i = 0;
+    while (i < sizeof(lo) - 1 && val[i] != '\0') {
+        char c = val[i];
+        if (c >= 'A' && c <= 'Z') {
+            c = (char)(c + ('a' - 'A'));
+        }
+        lo[i] = c;
+        i++;
+    }
+    lo[i] = '\0';
+
+    if      (strcmp(lo, "debug") == 0) { cbm_log_set_level(CBM_LOG_DEBUG); }
+    else if (strcmp(lo, "info")  == 0) { cbm_log_set_level(CBM_LOG_INFO);  }
+    else if (strcmp(lo, "warn")  == 0) { cbm_log_set_level(CBM_LOG_WARN);  }
+    else if (strcmp(lo, "error") == 0) { cbm_log_set_level(CBM_LOG_ERROR); }
+    else if (strcmp(lo, "none")  == 0) { cbm_log_set_level(CBM_LOG_NONE);  }
+    else {
+        /* Try numeric: 0=debug 1=info 2=warn 3=error 4=none */
+        char *end;
+        long n = strtol(val, &end, 10);
+        if (end != val && *end == '\0' && n >= CBM_LOG_DEBUG && n <= CBM_LOG_NONE) {
+            cbm_log_set_level((CBMLogLevel)n);
+        }
+        /* Unknown value: leave level unchanged (fail-open). */
+    }
+}
+
 void cbm_log_set_sink(cbm_log_sink_fn fn) {
     g_log_sink = fn;
 }

src/foundation/log.h

@@ -5,7 +5,7 @@
  *   - All output goes to stderr (stdout is reserved for MCP JSON-RPC)
  *   - Structured format: "level=info msg=pass.timing pass=defs elapsed_ms=42"
  *   - Levels: DEBUG, INFO, WARN, ERROR
- *   - Level filtering at compile time (CBM_LOG_MIN_LEVEL) and runtime
+ *   - Level filtering at runtime via CBM_LOG_LEVEL env var, or cbm_log_set_level()
  *   - Thread-safe (each fprintf is atomic on POSIX for lines < PIPE_BUF)
  */
 #ifndef CBM_LOG_H
@@ -21,12 +21,17 @@ typedef enum {
     CBM_LOG_NONE = 4 /* disable all logging */
 } CBMLogLevel;
 
+/* Initialise log level from the CBM_LOG_LEVEL environment variable.
+ * Accepted values (case-insensitive): debug, info, warn, error, none.
+ * Unknown values are silently ignored and the level stays at its current
+ * value. Call once at startup, before the first log statement. */
+void cbm_log_init_from_env(void);
+
 /* Set minimum log level (default: INFO). */
 void cbm_log_set_level(CBMLogLevel level);
 
 /* Get current log level. */
 CBMLogLevel cbm_log_get_level(void);
-
 /* Core logging function. msg is a short semantic tag.
  * Variadic args are key-value pairs: (const char *key, const char *value)...
  * Terminated by NULL key.

src/main.c

@@ -340,6 +340,7 @@ static void setup_signal_handlers(void) {
 
 int main(int argc, char **argv) {
     cbm_profile_init(); /* reads CBM_PROFILE env var, gates all prof macros */
+    cbm_log_init_from_env(); /* apply CBM_LOG_LEVEL before any output */
     int subcmd = handle_subcommand(argc, argv);
     if (subcmd >= 0) {
         return subcmd;

tests/test_log.c

@@ -112,11 +112,113 @@ TEST(log_int_helper) {
     PASS();
 }
 
+TEST(log_level_from_env_valid) {
+    /* Valid level strings set the expected level */
+    cbm_setenv("CBM_LOG_LEVEL", "error", 1);
+    cbm_log_init_from_env();
+    ASSERT_EQ(cbm_log_get_level(), CBM_LOG_ERROR);
+
+    cbm_setenv("CBM_LOG_LEVEL", "warn", 1);
+    cbm_log_init_from_env();
+    ASSERT_EQ(cbm_log_get_level(), CBM_LOG_WARN);
+
+    cbm_setenv("CBM_LOG_LEVEL", "debug", 1);
+    cbm_log_init_from_env();
+    ASSERT_EQ(cbm_log_get_level(), CBM_LOG_DEBUG);
+
+    cbm_setenv("CBM_LOG_LEVEL", "none", 1);
+    cbm_log_init_from_env();
+    ASSERT_EQ(cbm_log_get_level(), CBM_LOG_NONE);
+
+    cbm_setenv("CBM_LOG_LEVEL", "info", 1);
+    cbm_log_init_from_env();
+    ASSERT_EQ(cbm_log_get_level(), CBM_LOG_INFO);
+
+    cbm_unsetenv("CBM_LOG_LEVEL");
+    cbm_log_set_level(CBM_LOG_INFO); /* restore */
+    PASS();
+}
+
+TEST(log_level_from_env_case_insensitive) {
+    /* Level strings are matched case-insensitively */
+    cbm_setenv("CBM_LOG_LEVEL", "ERROR", 1);
+    cbm_log_init_from_env();
+    ASSERT_EQ(cbm_log_get_level(), CBM_LOG_ERROR);
+
+    cbm_setenv("CBM_LOG_LEVEL", "Warn", 1);
+    cbm_log_init_from_env();
+    ASSERT_EQ(cbm_log_get_level(), CBM_LOG_WARN);
+
+    cbm_unsetenv("CBM_LOG_LEVEL");
+    cbm_log_set_level(CBM_LOG_INFO); /* restore */
+    PASS();
+}
+
+TEST(log_level_from_env_unknown_ignored) {
+    /* Unknown values leave the level unchanged */
+    cbm_log_set_level(CBM_LOG_INFO);
+    cbm_setenv("CBM_LOG_LEVEL", "verbose", 1);
+    cbm_log_init_from_env();
+    ASSERT_EQ(cbm_log_get_level(), CBM_LOG_INFO);
+
+    cbm_unsetenv("CBM_LOG_LEVEL");
+    PASS();
+}
+
+TEST(log_level_from_env_unset_ignored) {
+    /* Missing env var leaves the level unchanged */
+    cbm_unsetenv("CBM_LOG_LEVEL");
+    cbm_log_set_level(CBM_LOG_WARN);
+    cbm_log_init_from_env();
+    ASSERT_EQ(cbm_log_get_level(), CBM_LOG_WARN);
+
+    cbm_log_set_level(CBM_LOG_INFO); /* restore */
+    PASS();
+}
+
+TEST(log_level_from_env_numeric) {
+    /* Numeric values mirror the CBMLogLevel enum: 0=debug 1=info 2=warn 3=error 4=none */
+    cbm_setenv("CBM_LOG_LEVEL", "0", 1);
+    cbm_log_init_from_env();
+    ASSERT_EQ(cbm_log_get_level(), CBM_LOG_DEBUG);
+
+    cbm_setenv("CBM_LOG_LEVEL", "1", 1);
+    cbm_log_init_from_env();
+    ASSERT_EQ(cbm_log_get_level(), CBM_LOG_INFO);
+
+    cbm_setenv("CBM_LOG_LEVEL", "2", 1);
+    cbm_log_init_from_env();
+    ASSERT_EQ(cbm_log_get_level(), CBM_LOG_WARN);
+
+    cbm_setenv("CBM_LOG_LEVEL", "3", 1);
+    cbm_log_init_from_env();
+    ASSERT_EQ(cbm_log_get_level(), CBM_LOG_ERROR);
+
+    cbm_setenv("CBM_LOG_LEVEL", "4", 1);
+    cbm_log_init_from_env();
+    ASSERT_EQ(cbm_log_get_level(), CBM_LOG_NONE);
+
+    /* Out-of-range numeric: leave level unchanged */
+    cbm_log_set_level(CBM_LOG_INFO);
+    cbm_setenv("CBM_LOG_LEVEL", "5", 1);
+    cbm_log_init_from_env();
+    ASSERT_EQ(cbm_log_get_level(), CBM_LOG_INFO);
+
+    cbm_unsetenv("CBM_LOG_LEVEL");
+    cbm_log_set_level(CBM_LOG_INFO); /* restore */
+    PASS();
+}
+
 SUITE(log) {
     RUN_TEST(log_level_default);
     RUN_TEST(log_level_set);
     RUN_TEST(log_info_output);
     RUN_TEST(log_filtered_by_level);
     RUN_TEST(log_error_output);
     RUN_TEST(log_int_helper);
+    RUN_TEST(log_level_from_env_valid);
+    RUN_TEST(log_level_from_env_case_insensitive);
+    RUN_TEST(log_level_from_env_unknown_ignored);
+    RUN_TEST(log_level_from_env_unset_ignored);
+    RUN_TEST(log_level_from_env_numeric);
 }