diff --git a/CLAUDE.md b/CLAUDE.md
index 310b46b0..1f7349fd 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -301,7 +301,7 @@ Two-stage filtering eliminates false positives:
 
 ### `.ralphrc` Parsing (Issue #346)
 
-`.ralphrc` is repository-controlled, so it is parsed as data and never sourced. The grammar and the command-key policy live in **lib/ralphrc.sh** (`ralphrc_parse_line`, `ralphrc_value_allowed`, `ralphrc_get`) and are shared by every reader: `load_ralphrc()` in ralph_loop.sh, `ralph_import.sh` (and `ralph-queue`, which sources it; env `CLAUDE_CODE_CMD` now wins there too) and `tools/inspect-allowed-tools.sh` — never add a new `.ralphrc` reader that greps or sources the file. `load_ralphrc()`: only `KEY=VALUE` lines (optional `export`, quotes, trailing `# comment`, CRLF tolerated) for allowlisted keys are applied via `printf -v`; values are literal — `$`, backticks, `\` and control characters are rejected in every value even when single-quoted (values reach bash arithmetic, where `a[$(cmd)]` executes, and `echo -e`), plus `;|&<>()` and quotes when unquoted; rejected lines are skipped with a WARN, as are unknown keys and malformed lines. Bad lines are never fatal, so the `_env_*` precedence restore always runs. Every allowlisted key (except the legacy aliases, `PROMPT_FILE` and `RALPH_DIR`) needs an `_env_*` snapshot + restore line, or the file beats the environment (Issue #369, structural guard test); keys a lib defaults at source time (`CB_*` thresholds, sandbox, sync) are snapshotted in the block BEFORE the lib source block — snapshotting after would record the lib default as an env value and make `.ralphrc` ineffective (guarded by the real-script tests in `test_ralphrc_security.bats`). Keys written by ralph-enable for reference only (`PROJECT_NAME`, `PROJECT_TYPE`, `TASK_SOURCES`, …) are accepted silently. Command-bearing keys accept only stock values from the file — `CLAUDE_CODE_CMD` (`claude` / `npx @anthropic-ai/claude-code`), `SANDBOX_DOCKER_IMAGE` (`ralph-sandbox:latest` / the GHCR image), `SANDBOX_E2B_TEMPLATE` (`base`), `SANDBOX_DOCKER_NETWORK` (`bridge`/`none`, never `host`), `RALPH_SHELL_INIT_FILE`, `SANDBOX_E2B_SANDBOX_ID` and `RALPH_DIR` (none — RALPH_DIR is env-only, Issue #352: an exported value relocates all state, and `validate_ralph_integrity` maps its `.ralph` entries onto it); every CLI flag that sets a `.ralphrc` key is captured as `_cli_*` and re-applied after `load_ralphrc` (structural guard test enforces it); repo-controlled values are printed only through `ralphrc_display` (control chars and backslashes → `?`, safe under `echo -e`); `--prompt` now wins over `PROMPT_FILE` from `.ralphrc` (`_cli_PROMPT_FILE`); custom values come from the environment or `--sandbox-image`/`--sandbox-template`. Bash 3.2-safe (no associative arrays). Tests: `tests/unit/test_ralphrc_security.bats` (incl. the issue's reproduction run against the real `ralph_loop.sh --dry-run`).
+`.ralphrc` is repository-controlled, so it is parsed as data and never sourced. The grammar and the command-key policy live in **lib/ralphrc.sh** (`ralphrc_parse_line`, `ralphrc_value_allowed`, `ralphrc_get`) and are shared by every reader: `load_ralphrc()` in ralph_loop.sh, `ralph_import.sh` (and `ralph-queue`, which sources it; env `CLAUDE_CODE_CMD` now wins there too) and `tools/inspect-allowed-tools.sh` — never add a new `.ralphrc` reader that greps or sources the file. `load_ralphrc()`: only `KEY=VALUE` lines (optional `export`, quotes, trailing `# comment`, CRLF tolerated) for allowlisted keys are applied via `printf -v`; values are literal — `$`, backticks, `\` and control characters are rejected in every value even when single-quoted (values reach bash arithmetic, where `a[$(cmd)]` executes, and `echo -e`), plus `;|&<>()` and quotes when unquoted; rejected lines are skipped with a WARN, as are unknown keys and malformed lines. Bad lines are never fatal, so the `_env_*` precedence restore always runs. Every allowlisted key (except the legacy aliases, `PROMPT_FILE` and `RALPH_DIR`) needs an `_env_*` snapshot + restore line, or the file beats the environment (Issue #369, structural guard test); keys a lib defaults at source time (`CB_*` thresholds, sandbox, sync) are snapshotted in the block BEFORE the lib source block — snapshotting after would record the lib default as an env value and make `.ralphrc` ineffective (guarded by the real-script tests in `test_ralphrc_security.bats`). Keys written by ralph-enable for reference only (`PROJECT_NAME`, `PROJECT_TYPE`, `TASK_SOURCES`, …) are accepted silently. Command-bearing keys accept only stock values from the file — `CLAUDE_CODE_CMD` (`claude` / `npx @anthropic-ai/claude-code`), `SANDBOX_DOCKER_IMAGE` (`ralph-sandbox:latest` / the GHCR image), `SANDBOX_E2B_TEMPLATE` (`base`), `SANDBOX_DOCKER_NETWORK` (`bridge`/`none`, never `host`), `RALPH_SHELL_INIT_FILE`, `SANDBOX_E2B_SANDBOX_ID` and `RALPH_DIR` (none — RALPH_DIR is env-only, Issue #352: an exported value relocates all state, and `validate_ralph_integrity` maps its `.ralph` entries onto it); every CLI flag that sets a `.ralphrc` key is captured as `_cli_*` and re-applied after `load_ralphrc` (structural guard test enforces it); `--monitor` puts every non-empty `_env_*` snapshot on the tmux loop pane's command as `KEY=%q-value` (derived from the snapshots, so new keys forward automatically), because a running tmux server gives panes its own environment (Issue #378); repo-controlled values are printed only through `ralphrc_display` (control chars and backslashes → `?`, safe under `echo -e`); `--prompt` now wins over `PROMPT_FILE` from `.ralphrc` (`_cli_PROMPT_FILE`); custom values come from the environment or `--sandbox-image`/`--sandbox-template`. Bash 3.2-safe (no associative arrays). Tests: `tests/unit/test_ralphrc_security.bats` (incl. the issue's reproduction run against the real `ralph_loop.sh --dry-run`).
 
 ### File Protection (Issue #149)
 
diff --git a/ralph_loop.sh b/ralph_loop.sh
index 6cfafdf0..e5771e19 100755
--- a/ralph_loop.sh
+++ b/ralph_loop.sh
@@ -589,13 +589,24 @@ setup_tmux_session() {
         tmux send-keys -t "$session_name:${base_win}.${pane2}" "${env_prefix}'$ralph_home/ralph_monitor.sh'" Enter
     fi
 
+    # The user's explicit environment rides on the loop command for the same
+    # reason, so it still beats .ralphrc in the pane (Issue #378). Derived from
+    # the _env_* snapshots: a new snapshotted key is forwarded automatically.
+    # This runs before main() loads .ralphrc, so a non-empty snapshot is
+    # always the user's own value. CLI flags appended below still win.
+    # Like the RALPH_DIR prefix, %q output assumes a bash-compatible pane shell.
+    local loop_env="" snap
+    for snap in "${!_env_@}"; do
+        [[ -n "${!snap}" ]] && loop_env+="${snap#_env_}=$(printf '%q' "${!snap}") "
+    done
+
     # Start ralph loop in the left pane (exclude tmux flag to avoid recursion)
     # Forward all CLI parameters that were set by the user
     local ralph_cmd
     if command -v ralph &> /dev/null; then
-        ralph_cmd="${env_prefix}ralph"
+        ralph_cmd="${env_prefix}${loop_env}ralph"
     else
-        ralph_cmd="${env_prefix}'$ralph_home/ralph_loop.sh'"
+        ralph_cmd="${env_prefix}${loop_env}'$ralph_home/ralph_loop.sh'"
     fi
 
     # Always use --live mode in tmux for real-time streaming
@@ -691,9 +702,10 @@ setup_tmux_session() {
     # validation ever runs, so explicit CLI --sync-* flags with the docker
     # provider must be rejected now — silently dropping them would make
     # --monitor behave differently from a plain run (CodeRabbit, PR #305).
-    # Env-supplied SYNC_* with docker is merely not forwarded (a plain run
-    # ignores it the same way); an empty provider may still become e2b via
-    # the child's .ralphrc, so it forwards.
+    # Env-supplied SYNC_* with docker is not forwarded as a flag (it rides
+    # in the env prefix above, which a docker child ignores just like a plain
+    # run does); an empty provider may still become e2b via the child's
+    # .ralphrc, so it forwards.
     if [[ "${SANDBOX_PROVIDER:-}" == "docker" ]]; then
         if [[ -n "${_cli_SYNC_INCLUDE:-}${_cli_SYNC_EXCLUDE:-}" ]]; then
             log_status "ERROR" "--sync-include/--sync-exclude do not apply to --sandbox docker (the bind mount shares the whole project in real time)"
diff --git a/tests/integration/test_tmux_integration.bats b/tests/integration/test_tmux_integration.bats
index 3063def1..c3fb2614 100644
--- a/tests/integration/test_tmux_integration.bats
+++ b/tests/integration/test_tmux_integration.bats
@@ -721,3 +721,72 @@ assert_tmux_called_with() {
     pane1_line=$(grep -E "tmux send-keys -t [^ ]+\.1 " "$TMUX_CALL_LOG" | head -1)
     [[ "$pane1_line" == *"tail -f '/tmp/ralph-abs-state/live.log'"* ]] || { echo "$pane1_line"; false; }
 }
+
+# Issue #378: a running tmux server gives panes its own environment, so the
+# user's explicit environment values must ride on the loop pane's command.
+_pane0_cmd() {
+    # The logged line is "tmux send-keys -t <session>:<win>.0 <command> Enter"
+    local line
+    line=$(grep -E "tmux send-keys -t [^ ]+\.0 " "$TMUX_CALL_LOG" | head -1)
+    line="${line#tmux send-keys -t * }"
+    printf '%s' "${line% Enter}"
+}
+
+@test "setup_tmux_session forwards every env-snapshotted key to the loop pane (#378)" {
+    local keys key
+    keys=$(grep -oE '^_env_[A-Z0-9_]+=' "${BATS_TEST_DIRNAME}/../../ralph_loop.sh" | sed 's/^_env_//; s/=$//' | sort -u)
+    [[ $(wc -l <<<"$keys") -ge 40 ]]
+    for key in $keys; do
+        printf -v "_env_$key" '%s' "v-$key"
+    done
+
+    run setup_tmux_session
+    [ "$status" -eq 0 ]
+
+    local cmd; cmd=$(_pane0_cmd)
+    for key in $keys; do
+        [[ "$cmd" == *"$key=v-$key "* ]] || fail "$key not forwarded: $cmd"
+    done
+    # The monitor pane only needs RALPH_DIR
+    [[ $(grep -cE "tmux send-keys -t [^ ]+\.2 .*CB_NO_PROGRESS_THRESHOLD=" "$TMUX_CALL_LOG") -eq 0 ]]
+}
+
+@test "setup_tmux_session quotes forwarded env values byte-exact with no injection (#378)" {
+    mkdir -p "$TEST_TEMP_DIR/bin"
+    cat > "$TEST_TEMP_DIR/bin/ralph" << 'SH'
+#!/bin/bash
+printf '%s' "$CLAUDE_MODEL" > "$OUT_DIR/model"
+printf '%s' "$OPTIONAL_SECTIONS" > "$OUT_DIR/sections"
+printf '%s' "$CLAUDE_CODE_CMD" > "$OUT_DIR/cmd"
+SH
+    chmod +x "$TEST_TEMP_DIR/bin/ralph"
+    export PATH="$TEST_TEMP_DIR/bin:$PATH" OUT_DIR="$TEST_TEMP_DIR"
+
+    local model='a b;  touch PWNED_1; $(touch PWNED_2) `touch PWNED_3`'
+    local sections="Nice to Have, it's \"Future\" \\ & | > <"
+    local cmd_val=$'npx @anthropic-ai/claude-code\ttab\nnewline'
+    _env_CLAUDE_MODEL="$model" _env_OPTIONAL_SECTIONS="$sections" _env_CLAUDE_CODE_CMD="$cmd_val"
+    run setup_tmux_session
+    [ "$status" -eq 0 ]
+
+    # Run the pane command the way the pane's shell would
+    bash -c "$(_pane0_cmd)"
+    assert_equal "$(cat "$TEST_TEMP_DIR/model")" "$model"
+    assert_equal "$(cat "$TEST_TEMP_DIR/sections")" "$sections"
+    assert_equal "$(cat "$TEST_TEMP_DIR/cmd")" "$cmd_val"
+    [[ ! -e PWNED_1 && ! -e PWNED_2 && ! -e PWNED_3 ]]
+}
+
+@test "setup_tmux_session forwards only keys set in the environment (#378)" {
+    _env_CB_NO_PROGRESS_THRESHOLD="10"
+    _env_CLAUDE_MODEL=""
+
+    run setup_tmux_session
+    [ "$status" -eq 0 ]
+
+    local cmd; cmd=$(_pane0_cmd)
+    [[ "$cmd" == *"CB_NO_PROGRESS_THRESHOLD=10 "* ]]
+    # Empty or absent snapshots leave .ralphrc in charge inside the pane
+    [[ "$cmd" != *"CLAUDE_MODEL="* ]]
+    [[ "$cmd" != *"MAX_CONSECUTIVE_TEST_LOOPS="* ]]
+}