v0.0.42 - Add C qrexec client example using high-level nostr_signer API with nostr_index selector; sync nostr_core_lib with qrexec transport and index support

Makefile

@@ -43,6 +43,7 @@ TEST_MNEMONIC_INPUT_TARGET := $(BUILD_DIR)/test_mnemonic_input
 EXAMPLE_GET_PUBLIC_KEY_TARGET := $(BUILD_DIR)/example_get_public_key_client
 EXAMPLE_SIGN_EVENT_TARGET := $(BUILD_DIR)/example_sign_event_client
 EXAMPLE_GET_PUBKEY_TCP_TARGET := $(BUILD_DIR)/example_get_pubkey_tcp
+EXAMPLE_GET_PUBKEY_QREXEC_TARGET := $(BUILD_DIR)/example_get_pubkey_qrexec
 
 .PHONY: all lib dev static static-debug static-arm64 firmware-feather test test-integration test-mnemonic test-mnemonic-input test-role test-selector test-enforcement test-dispatcher test-policy test-socket-name test-auth-envelope test-qrexec-auth examples test-client clean
 
@@ -109,7 +110,7 @@ test-qrexec-auth: $(TEST_QREXEC_AUTH_TARGET) $(TARGET_DEV)
 
 test-client: examples
 
-examples: $(EXAMPLE_GET_PUBLIC_KEY_TARGET) $(EXAMPLE_SIGN_EVENT_TARGET) $(EXAMPLE_GET_PUBKEY_TCP_TARGET)
+examples: $(EXAMPLE_GET_PUBLIC_KEY_TARGET) $(EXAMPLE_SIGN_EVENT_TARGET) $(EXAMPLE_GET_PUBKEY_TCP_TARGET) $(EXAMPLE_GET_PUBKEY_QREXEC_TARGET)
 
 $(TEST_MNEMONIC_TARGET): $(TEST_DIR)/test_mnemonic.c $(SRC_DIR)/mnemonic.c $(SRC_DIR)/secure_mem.c
 	@mkdir -p $(BUILD_DIR)
@@ -167,5 +168,9 @@ $(EXAMPLE_GET_PUBKEY_TCP_TARGET): $(EXAMPLES_DIR)/get_pubkey_tcp.c
 	@mkdir -p $(BUILD_DIR)
 	$(CC) $(CFLAGS) $(EXAMPLES_DIR)/get_pubkey_tcp.c -o $(EXAMPLE_GET_PUBKEY_TCP_TARGET) $(LDFLAGS)
 
+$(EXAMPLE_GET_PUBKEY_QREXEC_TARGET): $(EXAMPLES_DIR)/get_pubkey_qrexec.c
+	@mkdir -p $(BUILD_DIR)
+	$(CC) $(CFLAGS) $(EXAMPLES_DIR)/get_pubkey_qrexec.c -o $(EXAMPLE_GET_PUBKEY_QREXEC_TARGET) $(LDFLAGS)
+
 clean:
 	rm -rf $(BUILD_DIR)

README.md

@@ -247,6 +247,8 @@ Discovery:
 - `nsigner --listen stdio` runs one framed JSON-RPC request/response over stdin/stdout.
 - `nsigner --listen qrexec` is the same stdio framing mode, but caller identity can be derived from `QREXEC_REMOTE_DOMAIN` (displayed as `qubes:<source-vm>`).
 - `nsigner --listen tcp:IPv4:PORT` or `tcp:[IPv6]:PORT` enables TCP listening for non-AF_UNIX clients (for example `tcp:127.0.0.1:8080`, `tcp:[::]:8080`, or `tcp:[fd00::1234]:8080`).
+- `nsigner bridge --to <socket-name>` is a stateless relay for Qubes qrexec: reads one framed request from stdin, forwards it to a persistent signer's abstract unix socket, and relays the response to stdout. Used as the `qubes.NsignerRpc` service entrypoint. See [§8.3](#83-qubes-os-qube) and [`plans/qrexec_persistent_bridge.md`](plans/qrexec_persistent_bridge.md).
+- `--bridge-source-trusted` (unix listener only): marks the socket as a trusted bridge endpoint. Each connection sends a framed `{"qrexec_source":"<vm>"}` preamble before the request, and the caller identity is composed as `qubes:<vm>` — matching the native qrexec identity path. This enables a persistent signer (mnemonic in mlock'd RAM) to receive qrexec-routed requests without spawning a fresh process per call.
 
 ### 7.2 ESP32 MCU: TinyUSB composite (CDC + WebUSB)
 
@@ -283,7 +285,43 @@ MCU target reuses mnemonic/role/selector/enforcement/dispatcher core and swaps t
 
 ### 8.3 Qubes OS qube
 
-Qubes deployment runs `n_signer` in a dedicated signer qube as a foreground process under explicit user session control. Transport binding is platform-specific, but lifecycle and memory-only state model are unchanged.
+Qubes deployment runs `n_signer` in a dedicated signer qube (e.g. `nostr_signer`) as a foreground process under explicit user session control. The mnemonic lives only in mlock'd RAM in that qube — a compromised agent in a caller qube cannot read it (hypervisor-enforced memory isolation).
+
+Two transport paths are supported:
+
+**FIPS/TCP** — the signer listens on `tcp:[::]:8080` and FIPS carries traffic between qubes as an IPv6 mesh substrate. See [`documents/FIPS_DEPLOYMENT.md`](documents/FIPS_DEPLOYMENT.md).
+
+**Qubes qrexec bridge** (recommended for no-network deployments) — a persistent signer listens on an abstract unix socket, and a stateless `nsigner bridge` relay (the `qubes.NsignerRpc` qrexec service) forwards one request per qrexec invocation. No network, no FIPS — pure intra-host IPC. Caller identity is `qubes:<source-vm>` (from `QREXEC_REMOTE_DOMAIN`), relayed via a trusted preamble. See [`plans/qrexec_persistent_bridge.md`](plans/qrexec_persistent_bridge.md) for the full design.
+
+#### Qrexec bridge setup
+
+**In the signer qube** (`nostr_signer`):
+
+```bash
+# Install nsigner and the qrexec service
+bash setup_signer_qube.sh    # from packaging/qubes/
+
+# Start the persistent signer (mnemonic entered at terminal, in mlock'd RAM)
+~/.local/bin/nsigner --listen unix --socket-name nsigner --bridge-source-trusted
+```
+
+**In dom0**:
+
+```bash
+# Install policy and tag the signer qube
+bash setup_dom0.sh nostr_signer    # from packaging/qubes/
+```
+
+The dom0 policy allows trusted caller qubes without a popup (memory isolation is the real security boundary) and asks for confirmation from any other qube. The signer's own approval prompt at the `nostr_signer` terminal is the operation-level gate.
+
+**From a caller qube**:
+
+```bash
+# JavaScript example (uses qrexec-client-vm, no auth envelope needed)
+node examples/n_signer_qube_example_qrexec.js nostr_signer
+```
+
+Setup scripts and policy are in [`packaging/qubes/`](packaging/qubes/). See also [`documents/QUBES_OS.md`](documents/QUBES_OS.md) and [`documents/qubes_client_examples.md`](documents/qubes_client_examples.md).
 
 ## 9. Usage
 
@@ -319,6 +357,18 @@ TCP transport mode (no TUI; serves requests until terminated):
 nsigner --listen tcp:[::]:8080
 ```
 
+Qrexec bridge mode (stateless relay to a persistent signer's unix socket; used as the `qubes.NsignerRpc` service):
+
+```bash
+nsigner bridge --to nsigner
+```
+
+Persistent signer for qrexec bridge (unix listener with trusted source-qube preamble):
+
+```bash
+nsigner --listen unix --socket-name nsigner --bridge-source-trusted
+```
+
 ### 9.2 Send a request (client mode)
 
 From another terminal, target the signer by its socket name:
@@ -414,6 +464,11 @@ These items are designed and worth doing, but are not in the current implementat
 - [`documents/CLIENT_IMPLEMENTATION.md`](documents/CLIENT_IMPLEMENTATION.md): client integration contract and framing behavior
 - [`documents/QUBES_OS.md`](documents/QUBES_OS.md): Qubes OS deployment/integration checklist for dedicated signer qubes
 - [`documents/FIPS_DEPLOYMENT.md`](documents/FIPS_DEPLOYMENT.md): Tier-1 FIPS deployment runbook using loopback TCP listener
+- [`plans/qrexec_persistent_bridge.md`](plans/qrexec_persistent_bridge.md): design for the qrexec → unix-socket bridge transport (persistent signer, no mnemonic on disk)
+- [`packaging/qubes/`](packaging/qubes/): qrexec service script, dom0 policy, and setup scripts for Qubes deployment
+- [`examples/n_signer_qube_example_qrexec.js`](examples/n_signer_qube_example_qrexec.js): JavaScript caller example using qrexec (no network, no auth envelope)
+- [`examples/n_signer_qube_example_fips.js`](examples/n_signer_qube_example_fips.js): JavaScript caller example using FIPS/TCP with auth envelope
+- [`examples/get_pubkey_tcp.c`](examples/get_pubkey_tcp.c): C caller example using TCP transport with auth envelope
 - [`plans/nsigner.md`](plans/nsigner.md): implementation plan and sequencing
 - [`plans/seed_phrase_uses.md`](plans/seed_phrase_uses.md): seed phrase domain/use catalog and caveats
 - [`firmware/feather_s3_tft`](firmware/feather_s3_tft): Feather ESP32-S3 Reverse TFT firmware (TinyUSB composite CDC + WebUSB signer PoC)

examples/get_pubkey_qrexec.c

@@ -0,0 +1,110 @@
+/*
+ * get_pubkey_qrexec.c — connect to a running n_signer in another Qubes qube
+ * via qrexec, using the high-level nostr_signer API from nostr_core_lib.
+ *
+ * This demonstrates the new nostr_core_lib client features:
+ *   - nostr_signer_nsigner_qrexec() — qrexec transport
+ *   - nostr_signer_nsigner_set_nostr_index() — index-based key selection
+ *
+ * Usage:
+ *   ./get_pubkey_qrexec <target_qube> [nostr_index]
+ *   ./get_pubkey_qrexec nostr_signer 0
+ *   ./get_pubkey_qrexec nostr_signer 1
+ *
+ * No auth envelope needed — qrexec identity comes from QREXEC_REMOTE_DOMAIN
+ * on the server side.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "nostr_common.h"
+#include "nostr_signer.h"
+#include "nip019.h"
+
+int main(int argc, char **argv) {
+    const char *target_qube;
+    const char *service_name = "qubes.NsignerRpc";
+    int nostr_index = 0;
+    nostr_signer_t *signer = NULL;
+    char pubkey_hex[65];
+    unsigned char pubkey_bytes[32];
+    char npub[128];
+    int rc;
+
+    if (argc < 2) {
+        fprintf(stderr, "Usage: %s <target_qube> [nostr_index]\n", argv[0]);
+        return 1;
+    }
+    target_qube = argv[1];
+    if (argc > 2) {
+        nostr_index = atoi(argv[2]);
+    }
+
+    if (nostr_init() != NOSTR_SUCCESS) {
+        fprintf(stderr, "failed to initialize crypto subsystem\n");
+        return 1;
+    }
+
+    printf("Connecting to n_signer in qube \"%s\" via qrexec (index %d)...\n",
+           target_qube, nostr_index);
+
+    /* Create a high-level signer backed by qrexec transport */
+    signer = nostr_signer_nsigner_qrexec(target_qube, service_name, NULL, 30000);
+    if (signer == NULL) {
+        fprintf(stderr, "failed to create qrexec signer (is qrexec-client-vm available?)\n");
+        nostr_cleanup();
+        return 1;
+    }
+
+    /* Select key by nostr_index (NIP-06 m/44'/1237'/N'/0/0) */
+    if (nostr_signer_nsigner_set_nostr_index(signer, nostr_index) != NOSTR_SUCCESS) {
+        fprintf(stderr, "failed to set nostr_index\n");
+        nostr_signer_free(signer);
+        nostr_cleanup();
+        return 1;
+    }
+
+    /* Request the public key */
+    rc = nostr_signer_get_public_key(signer, pubkey_hex);
+    if (rc != NOSTR_SUCCESS) {
+        if (rc == NOSTR_ERROR_NSIGNER_INDEX_NOT_ALLOWED) {
+            fprintf(stderr, "DENIED: index %d is not in the signer's whitelist\n", nostr_index);
+        } else if (rc == NOSTR_ERROR_NSIGNER_POLICY_DENIED) {
+            fprintf(stderr, "DENIED: policy denied (caller not approved at signer terminal)\n");
+        } else {
+            fprintf(stderr, "get_public_key failed: error code %d\n", rc);
+        }
+        nostr_signer_free(signer);
+        nostr_cleanup();
+        return 1;
+    }
+
+    /* Convert hex pubkey to npub (bech32) */
+    {
+        int i;
+        for (i = 0; i < 32; i++) {
+            unsigned int byte;
+            if (sscanf(pubkey_hex + 2 * i, "%2x", &byte) != 1) {
+                fprintf(stderr, "failed to parse hex pubkey\n");
+                nostr_signer_free(signer);
+                nostr_cleanup();
+                return 1;
+            }
+            pubkey_bytes[i] = (unsigned char)byte;
+        }
+    }
+    if (nostr_key_to_bech32(pubkey_bytes, "npub", npub) != NOSTR_SUCCESS) {
+        fprintf(stderr, "failed to convert to npub\n");
+        nostr_signer_free(signer);
+        nostr_cleanup();
+        return 1;
+    }
+
+    printf("index %d: hex=%s  npub=%s\n", nostr_index, pubkey_hex, npub);
+
+    nostr_signer_free(signer);
+    nostr_cleanup();
+    return 0;
+}

install_qube_fips_nsigner.sh

@@ -178,6 +178,16 @@ set -euo pipefail
 export PATH="$HOME/.local/bin:$PATH"
 LISTEN_TARGET="${NSIGNER_LISTEN_TARGET:-tcp:[::]:8080}"
 
+# If first arg is "qrexec", start in unix bridge mode for Qubes qrexec.
+# Otherwise, pass any extra args through to nsigner (e.g. --allow-all).
+if [[ "${1:-}" == "qrexec" ]]; then
+  LISTEN_TARGET="unix"
+  EXTRA_ARGS="--socket-name nsigner --bridge-source-trusted"
+  shift
+else
+  EXTRA_ARGS="$*"
+fi
+
 echo "=== n_signer startup ==="
 echo "listen target: ${LISTEN_TARGET}"
 
@@ -208,7 +218,11 @@ fi
 echo
 echo "Starting signer..."
 echo "On first remote request, approve in prompt with [y] or [a]."
-exec "$HOME/.local/bin/nsigner" --listen "${LISTEN_TARGET}"
+if [[ -n "${EXTRA_ARGS}" ]]; then
+  exec "$HOME/.local/bin/nsigner" --listen "${LISTEN_TARGET}" ${EXTRA_ARGS}
+else
+  exec "$HOME/.local/bin/nsigner" --listen "${LISTEN_TARGET}"
+fi
 EOF
 
   chmod 0755 "${script_path}"

packaging/qubes/policy.d/40-nsigner.policy

@@ -1,5 +1,10 @@
 # Qubes OS qrexec policy for nsigner
 # Syntax: service +argument source target action
-# Allow specific qubes to reach the signer qube with user confirmation
+#
+# The ai qube is allowed without a dom0 popup (memory isolation is the
+# real security boundary — the signer's own approval prompt in the
+# nostr_signer terminal is the operation-level gate).
+qubes.NsignerRpc * ai @tag:nsigner-signer allow target=nostr_signer
+# Any other qube must get a dom0 confirmation popup.
 qubes.NsignerRpc * @anyvm @tag:nsigner-signer ask default_target=nostr_signer
 qubes.NsignerRpc * @anyvm @anyvm deny

packaging/qubes/setup_dom0.sh

@@ -0,0 +1,58 @@
+#!/bin/bash
+#
+# setup_dom0.sh — install qrexec policy and tag the signer qube in dom0.
+#
+# Run this in dom0. It creates /etc/qubes/policy.d/40-nsigner.policy
+# and tags the nostr_signer qube with 'nsigner-signer'.
+#
+# Usage:
+#   bash setup_dom0.sh [signer_qube_name]
+#
+# Default signer qube name is "nostr_signer".
+
+set -euo pipefail
+
+SIGNER_QUBE="${1:-nostr_signer}"
+
+echo "=== n_signer dom0 setup ==="
+echo "Signer qube: ${SIGNER_QUBE}"
+echo
+
+# Create policy directory if it doesn't exist
+sudo mkdir -p /etc/qubes/policy.d
+
+# Write the qrexec policy
+# The 'ai' qube is allowed without a dom0 popup (memory isolation is the
+# real security boundary; the signer's own approval prompt is the gate).
+# Any other qube gets a dom0 confirmation popup.
+echo "Installing qrexec policy to /etc/qubes/policy.d/40-nsigner.policy..."
+echo "# Qubes OS qrexec policy for nsigner" | sudo tee /etc/qubes/policy.d/40-nsigner.policy > /dev/null
+echo "qubes.NsignerRpc * ai @tag:nsigner-signer allow target=${SIGNER_QUBE}" | sudo tee -a /etc/qubes/policy.d/40-nsigner.policy > /dev/null
+echo "qubes.NsignerRpc * @anyvm @tag:nsigner-signer ask default_target=${SIGNER_QUBE}" | sudo tee -a /etc/qubes/policy.d/40-nsigner.policy > /dev/null
+echo "qubes.NsignerRpc * @anyvm @anyvm deny" | sudo tee -a /etc/qubes/policy.d/40-nsigner.policy > /dev/null
+
+echo "Policy installed. Contents:"
+cat /etc/qubes/policy.d/40-nsigner.policy
+echo
+
+# Tag the signer qube
+echo "Tagging ${SIGNER_QUBE} with 'nsigner-signer'..."
+qvm-tags "${SIGNER_QUBE}" add nsigner-signer
+echo "Tag added."
+echo
+
+# Verify
+echo "=== Verification ==="
+echo "Policy file:"
+ls -l /etc/qubes/policy.d/40-nsigner.policy
+echo
+echo "Tags on ${SIGNER_QUBE}:"
+qvm-tags "${SIGNER_QUBE}" list 2>/dev/null | grep nsigner || echo "(tag not found — check qube name)"
+echo
+echo "=== dom0 setup complete ==="
+echo
+echo "Next steps:"
+echo "  1. In ${SIGNER_QUBE}: run setup_signer_qube.sh"
+echo "  2. In ${SIGNER_QUBE}: start the persistent signer:"
+echo "     ~/.local/bin/nsigner --listen unix --socket-name nsigner --bridge-source-trusted"
+echo "  3. In caller qube: node examples/n_signer_qube_example_qrexec.js ${SIGNER_QUBE}"

packaging/qubes/setup_signer_qube.sh

@@ -0,0 +1,68 @@
+#!/bin/bash
+#
+# setup_signer_qube.sh — install nsigner v0.0.34+ and the qrexec bridge service
+# in the nostr_signer qube.
+#
+# Run this in the nostr_signer qube (as the regular user, not root).
+# It will:
+#   1. Run install_nsigner.sh to download the latest nsigner release (v0.0.34+)
+#   2. Install the qubes.NsignerRpc qrexec service (bridge mode)
+#   3. Print instructions for starting the persistent signer
+#
+# Usage:
+#   bash setup_signer_qube.sh
+
+set -euo pipefail
+
+NSIGNER_BIN="${HOME}/.local/bin/nsigner"
+SERVICE_DST="/etc/qubes-rpc/qubes.NsignerRpc"
+
+echo "=== n_signer qube setup ==="
+echo
+
+# Step 1: Update nsigner binary
+if [ -f "${HOME}/install_nsigner.sh" ]; then
+    echo "Step 1: Running install_nsigner.sh to update nsigner..."
+    bash "${HOME}/install_nsigner.sh"
+else
+    echo "Step 1: install_nsigner.sh not found in ${HOME}."
+    echo "  Make sure install_nsigner.sh is in your home directory first."
+    exit 1
+fi
+echo
+
+# Verify the bridge subcommand exists
+echo "Verifying bridge subcommand..."
+if ! "${NSIGNER_BIN}" bridge --help > /dev/null 2>&1; then
+    echo "ERROR: nsigner does not have the 'bridge' subcommand."
+    echo "  The installed version may be too old. Expected v0.0.34 or later."
+    "${NSIGNER_BIN}" --version
+    exit 1
+fi
+echo "OK: bridge subcommand available."
+"${NSIGNER_BIN}" --version
+echo
+
+# Step 2: Install the qrexec service
+echo "Step 2: Installing qrexec service to ${SERVICE_DST}..."
+echo '#!/bin/sh' | sudo tee "${SERVICE_DST}" > /dev/null
+echo '# qubes.NsignerRpc — stateless bridge to persistent nsigner unix socket' | sudo tee -a "${SERVICE_DST}" > /dev/null
+echo '# No mnemonic, no secrets. Relays QREXEC_REMOTE_DOMAIN as source-qube preamble.' | sudo tee -a "${SERVICE_DST}" > /dev/null
+echo "exec ${NSIGNER_BIN} bridge --to nsigner" | sudo tee -a "${SERVICE_DST}" > /dev/null
+sudo chmod 0755 "${SERVICE_DST}"
+
+echo "Service installed. Contents:"
+cat "${SERVICE_DST}"
+echo
+
+echo "=== Signer qube setup complete ==="
+echo
+echo "To start the persistent signer (mnemonic entered at terminal, in mlock'd RAM):"
+echo
+echo "  ${NSIGNER_BIN} --listen unix --socket-name nsigner --bridge-source-trusted"
+echo
+echo "The signer will prompt you for the mnemonic. It stays running with the"
+echo "mnemonic in RAM only — nothing on disk. Leave it running in a terminal."
+echo
+echo "Then from a caller qube (e.g. 'ai'):"
+echo "  node examples/n_signer_qube_example_qrexec.js nostr_signer"

plans/interactive_transport_selection.md

@@ -0,0 +1,143 @@
+# Plan: Interactive multi-transport selection at startup
+
+Status: design / ready for review.
+
+Related:
+- [`README.md`](../README.md) §7 Transport, §8.3 Qubes OS qube, §9 Usage
+- [`src/main.c`](../src/main.c) — argument parsing, main loop, TUI
+- [`src/server.c`](../src/server.c) — `server_ctx_t`, `server_start`, `server_handle_one`
+- [`plans/qrexec_persistent_bridge.md`](qrexec_persistent_bridge.md) — bridge design
+
+---
+
+## 1. Motivation
+
+The current CLI has many transport flags (`--listen`, `--socket-name`, `--bridge-source-trusted`, `--auth`, `--allow-all`) that the user must know in advance. For interactive use, this is unfriendly — the user just wants to answer "how should other programs reach this signer?"
+
+Additionally, the user may want **multiple transports active simultaneously** (e.g. unix socket for local clients + TCP for FIPS mesh clients + qrexec bridge for other qubes). Today only one `--listen` mode is supported at a time.
+
+---
+
+## 2. Design
+
+### 2.1 Interactive transport menu at startup
+
+After mnemonic entry and before the running phase, if no `--listen` flag was given (i.e. interactive mode), present a multi-select menu:
+
+```text
+Transport — how should other programs reach this signer?
+Select one or more (space to toggle, enter to confirm):
+
+  [x] 1. Local Unix socket (same machine/qube)
+  [ ] 2. Qubes qrexec bridge (other qubes via qrexec, no network)
+  [ ] 3. TCP listener (FIPS mesh or local network)
+  [ ] 4. Qrexec one-shot (legacy, one request per invocation)
+
+  [a] select all
+
+  (at least one must be selected)
+```
+
+Each selected transport gets configured with sensible defaults:
+
+| Choice | What it starts | Defaults |
+|---|---|---|
+| 1. Unix socket | `--listen unix` | socket name `nsigner` (or random if collision) |
+| 2. Qrexec bridge | `--listen unix --bridge-source-trusted` | socket name `nsigner`, accepts qrexec preamble |
+| 3. TCP | `--listen tcp:[::]:8080` | bind all interfaces, port 8080 |
+| 4. Qrexec one-shot | `--listen qrexec` | one request via stdin, then exit |
+
+**Choices 1 and 2 can coexist** — they're both unix listeners, just with different identity handling. Choice 2 implies choice 1's socket. If both are selected, the bridge-source-trusted flag is set on the single unix listener (it handles both local and bridge connections).
+
+**Choice 3 (TCP) can coexist with 1+2** — it's a separate listener on a different fd.
+
+**Choice 4 (qrexec one-shot) is mutually exclusive** with all others — it uses stdin/stdout and exits after one request. If selected alone, it runs the one-shot path. If selected with others, it's ignored with a warning (or: the user is told it can't combine).
+
+### 2.2 Multi-listener architecture
+
+Currently `main()` creates one `server_ctx_t` and polls `server.listen_fd` + `STDIN_FILENO`. To support multiple listeners:
+
+- Create an array of `server_ctx_t` (up to 3: unix, tcp, and optionally a second unix for bridge — though 1+2 collapse into one).
+- Each `server_ctx_t` gets its own `server_start()`.
+- The poll loop expands to poll all listener fds + STDIN_FILENO.
+- When a listener fd has activity, call `server_handle_one()` on that context.
+- The TUI status display shows all active transports.
+
+```text
+Connections
+listen: unix @nsigner (bridge-source-trusted)
+listen: tcp [::]:8080
+client: nsigner --socket-name nsigner client '<json>'
+```
+
+### 2.3 Coexistence with CLI flags
+
+- If `--listen` is given on the command line, **skip the interactive menu** (automation/scripting path unchanged).
+- If no `--listen` is given and stdin is a TTY, **show the interactive menu**.
+- If no `--listen` is given and stdin is NOT a TTY, **default to unix socket** (current behavior, for `--mnemonic-stdin` / `--mnemonic-fd` supervised launches).
+
+This preserves backward compatibility: all existing flags and scripts work unchanged. The menu is purely an interactive convenience.
+
+### 2.4 TUI implementation
+
+The menu uses the existing TUI rendering helpers (`tui_render_content_screen`, `tui_print`). It appears after mnemonic acceptance and before the status display. Navigation:
+
+- `1`-`4` or space: toggle a choice
+- `a`: select all (except 4, which is mutually exclusive)
+- `a`: select all (except 4, which is mutually exclusive)
+- `enter`: confirm and proceed to running phase (at least one must be selected)
+
+After confirmation, the selected listeners are started and the status display renders.
+
+### 2.5 Security considerations
+
+- The menu is purely a UX layer — it doesn't change the security model. Each transport still goes through the same policy/approval pipeline.
+- `--bridge-source-trusted` is only set if the user explicitly selects the qrexec bridge option. It's never silently enabled.
+- TCP listener still requires auth envelopes (existing behavior).
+- The menu doesn't offer `--allow-all`; that remains a CLI flag for users who want it.
+
+---
+
+## 3. Implementation checklist
+
+### 3.1 Multi-listener support in `main.c`
+- [ ] Replace single `server_ctx_t server` with an array (e.g. `server_ctx_t servers[3]`).
+- [ ] Add a `server_count` variable.
+- [ ] Expand the poll loop to poll all `servers[i].listen_fd` + STDIN_FILENO.
+- [ ] On activity, call `server_handle_one(&servers[i], ...)` for the matching fd.
+- [ ] `server_stop()` all on shutdown.
+
+### 3.2 Interactive menu
+- [ ] Add `prompt_transport_selection()` function in `main.c` (after mnemonic load, before server start).
+- [ ] Returns a bitmask of selected transports.
+- [ ] Only called when `listen_mode` was not set by CLI and stdin is a TTY.
+- [ ] Uses `tui_render_content_screen` + `read_line_stdin` for input.
+
+### 3.3 Transport setup from menu selection
+- [ ] Unix: `server_init` + `server_start` with `NSIGNER_LISTEN_UNIX`, socket name `nsigner`.
+- [ ] Qrexec bridge: same as unix + `server_set_bridge_source_trusted(&server, 1)`.
+- [ ] TCP: `server_init` + `server_start` with `NSIGNER_LISTEN_TCP`, target `tcp:[::]:8080`.
+- [ ] Qrexec one-shot: existing `NSIGNER_LISTEN_QREXEC` path (stdin, one request, exit).
+
+### 3.4 TUI status display
+- [ ] Update `render_status()` to show multiple active listeners.
+- [ ] Show `(bridge-source-trusted)` annotation on unix listeners that have it.
+
+### 3.5 Testing
+- [ ] Interactive: start nsigner with no `--listen`, select unix+TCP, verify both listeners work.
+- [ ] Interactive: select qrexec bridge, verify bridge connections get `qubes:<vm>` identity.
+- [ ] CLI: `--listen tcp:[::]:8080` still works (skips menu).
+- [ ] CLI: `--listen unix --bridge-source-trusted` still works (skips menu).
+- [ ] Non-TTY: `--mnemonic-stdin` without `--listen` defaults to unix (no menu).
+
+---
+
+## 4. Open questions
+
+1. **Should the menu remember the last selection?** n_signer has no config files (by design). We could store the preference in an env var or a `/tmp` file, but that violates the zero-filesystem-footprint principle. **Decision: no persistence — the menu appears fresh each time.**
+
+2. **Should there be a hotkey to add/remove transports at runtime?** E.g. press `t` in the TUI to bring up the transport menu again. This is a nice-to-have but adds complexity. **Decision: defer — the menu is startup-only for now.**
+
+3. **TCP port selection in the menu?** The menu could ask for a port number if TCP is selected. **Decision: default to 8080, let the user override with `--listen tcp:...` if they need a different port. Keep the menu simple.**
+
+4. **Socket name selection?** Same — default to `nsigner`, override with `--socket-name` if needed. **Decision: default, no prompt.**

plans/nostr_core_lib_client_updates.md

@@ -0,0 +1,123 @@
+# Plan: nostr_core_lib client updates for new n_signer features
+
+Status: design / ready for review.
+
+Related:
+- [`../nostr_core_lib/nostr_core/nsigner_transport.h`](../../nostr_core_lib/nostr_core/nsigner_transport.h) — transport vtable
+- [`../nostr_core_lib/nostr_core/nsigner_client.h`](../../nostr_core_lib/nostr_core/nsigner_client.h) — low-level client
+- [`../nostr_core_lib/nostr_core/nostr_signer.h`](../../nostr_core_lib/nostr_core/nostr_signer.h) — high-level signer
+- [`../nostr_core_lib/nostr_core/nostr_signer.c`](../../nostr_core_lib/nostr_core/nostr_signer.c) — `signer_remote_params_with_selector`
+- [`plans/qrexec_persistent_bridge.md`](qrexec_persistent_bridge.md) — qrexec bridge design
+- [`plans/interactive_transport_selection.md`](interactive_transport_selection.md) — index whitelist
+
+---
+
+## 1. Gaps identified
+
+The `nostr_core_lib` client stack was built before the recent n_signer features. Three gaps need filling:
+
+### 1.1 No `nostr_index` selector in the high-level API
+
+`signer_remote_params_with_selector()` ([`nostr_signer.c:287`](../../nostr_core_lib/nostr_core/nostr_signer.c:287)) only emits `{"role":"..."}`. It does not support `{"nostr_index":N}`, which is n_signer's primary key-selection mechanism for Nostr identities (NIP-06 `m/44'/1237'/N'/0/0`).
+
+The `nostr_signer_nsigner_*` constructors take a `const char* role` parameter. There's no way to say "use nostr_index 3" through the high-level API. Callers who want a specific Nostr identity by index must drop down to the low-level `nsigner_client_call` and build params manually — which is exactly what [`examples/get_pubkey_tcp.c`](../examples/get_pubkey_tcp.c) and [`examples/n_signer_qube_example_fips.js`](../examples/n_signer_qube_example_fips.js) do.
+
+### 1.2 No qrexec transport
+
+`nsigner_transport_open_*` supports unix, tcp, serial, fds — but not qrexec. On Qubes OS, the primary inter-qube path is `qrexec-client-vm <target> qubes.NsignerRpc`, which pipes framed I/O through stdin/stdout of a subprocess. There's no transport that wraps this.
+
+### 1.3 No error code mapping for `index_not_allowed` (2002)
+
+n_signer now returns `{"error":{"code":2002,"message":"index_not_allowed"}}` when the index whitelist denies a request. The client should surface this distinctly from `policy_denied` (2001) so callers can tell "this index isn't whitelisted" vs "this caller isn't approved".
+
+---
+
+## 2. Proposed changes
+
+### 2.1 Add `nostr_index` selector to the high-level API
+
+**Option A (minimal):** Add a new constructor variant that takes `nostr_index` instead of `role`:
+
+```c
+nostr_signer_t* nostr_signer_nsigner_unix_index(const char* socket_name, int nostr_index, int timeout_ms);
+nostr_signer_t* nostr_signer_nsigner_tcp_index(const char* host, int port, int nostr_index, int timeout_ms);
+/* etc. */
+```
+
+**Option B (cleaner):** Replace the `role` string parameter with a selector struct:
+
+```c
+typedef struct {
+    const char* role;       /* NULL = use default */
+    int nostr_index;        /* -1 = not set */
+    const char* role_path;  /* NULL = not set */
+} nsigner_selector_t;
+
+nostr_signer_t* nostr_signer_nsigner_unix(const char* socket_name, const nsigner_selector_t* selector, int timeout_ms);
+```
+
+**Option C (additive, chosen):** Keep existing constructors, add a setter for nostr_index:
+
+```c
+int nostr_signer_nsigner_set_nostr_index(nostr_signer_t* signer, int nostr_index);
+```
+
+This sets the index on the remote backend, and `signer_remote_params_with_selector` emits `{"nostr_index":N}` instead of `{"role":"..."}` when set. Existing callers using `role` are unaffected.
+
+**Decision: Option C** — additive, no API break, smallest change.
+
+### 2.2 Add qrexec transport
+
+New transport constructor:
+
+```c
+nsigner_transport_t* nsigner_transport_open_qrexec(const char* target_qube, const char* service_name, int timeout_ms);
+```
+
+Implementation: `fork()` + `execvp("qrexec-client-vm", [target_qube, service_name])` with `stdin`/`stdout` pipes. The `send_framed`/`recv_framed` vtable methods write/read through the pipes. `reconnect` re-spawns the subprocess (qrexec handles one request per invocation, so reconnect is mandatory before each call — same as the existing per-request reconnect pattern).
+
+The transport is stateless per call: each `reconnect` spawns a fresh `qrexec-client-vm` process, sends one framed request, reads one framed response, and the process exits. This matches the qrexec execution model.
+
+### 2.3 Add `nostr_signer_nsigner_qrexec` high-level constructor
+
+```c
+nostr_signer_t* nostr_signer_nsigner_qrexec(const char* target_qube, const char* service_name, const char* role, int timeout_ms);
+```
+
+Wraps `nsigner_transport_open_qrexec` + `nostr_signer_nsigner_from_transport`. No auth envelope needed — qrexec identity comes from `QREXEC_REMOTE_DOMAIN` on the server side.
+
+### 2.4 Surface `index_not_allowed` error distinctly
+
+Add to `nostr_common.h`:
+
+```c
+#define NOSTR_ERROR_NSIGNER_INDEX_NOT_ALLOWED -2002
+```
+
+In `nsigner_client_call` (or `nostr_signer` remote backend), when the response error code is 2002, map it to `NOSTR_ERROR_NSIGNER_INDEX_NOT_ALLOWED` so callers can distinguish it from generic policy denial.
+
+---
+
+## 3. Implementation checklist
+
+In `nostr_core_lib`:
+
+- [ ] `nsigner_transport.h` / `nsigner_transport.c`: add `nsigner_transport_open_qrexec(target_qube, service_name, timeout_ms)` — fork+exec `qrexec-client-vm`, pipe-based framed I/O, reconnect re-spawns.
+- [ ] `nostr_signer.h` / `nostr_signer.c`: add `nostr_signer_nsigner_qrexec(target_qube, service_name, role, timeout_ms)`.
+- [ ] `nostr_signer.c`: add `nostr_signer_nsigner_set_nostr_index(signer, nostr_index)`; update `signer_remote_params_with_selector` to emit `{"nostr_index":N}` when index is set.
+- [ ] `nostr_common.h`: add `NOSTR_ERROR_NSIGNER_INDEX_NOT_ALLOWED` error code.
+- [ ] `nsigner_client.c`: map error code 2002 to the new constant.
+- [ ] `NSIGNER_INTEGRATION.md`: document the qrexec transport, nostr_index selector, and index_not_allowed error.
+
+In `n_signer` (this repo):
+
+- [ ] Update [`examples/get_pubkey_tcp.c`](../examples/get_pubkey_tcp.c) to optionally use the high-level `nostr_signer` API with `nostr_index` selector (demonstrates the new client API).
+- [ ] Add a C example for the qrexec path using the new `nostr_signer_nsigner_qrexec` constructor.
+
+---
+
+## 4. Open questions
+
+1. **Should the qrexec transport live in `nostr_core_lib` or in a Qubes-specific addon?** The transport is only useful on Qubes OS, but `nostr_core_lib` is meant to be cross-platform. **Decision: put it in `nostr_core_lib` behind `NOSTR_ENABLE_NSIGNER_CLIENT` — it just won't work on non-Qubes hosts (execvp fails). No new feature flag needed.**
+
+2. **Should `nostr_signer_nsigner_set_nostr_index` override `role` or coexist?** n_signer rejects ambiguous selectors (both `role` and `nostr_index` set = `ambiguous_role_selector`). **Decision: setting nostr_index clears role, and vice versa. The setter is exclusive.**

src/main.c

@@ -412,6 +412,9 @@ typedef struct {
 } caller_identity_t;
 
 /* Server context */
+#define INDEX_WHITELIST_MAX 256
+#define INDEX_WHITELIST_BITMAP_SIZE (INDEX_WHITELIST_MAX / 8)
+
 typedef struct {
     char socket_name[SERVER_SOCKET_NAME_MAX]; /* abstract namespace name (without \0 prefix) */
     char last_error[256];
@@ -424,6 +427,9 @@ typedef struct {
     int socket_name_explicit;
     int auth_mode;
     int auth_skew_seconds;
+    int bridge_source_trusted;
+    int index_whitelist_active;
+    unsigned char index_whitelist[INDEX_WHITELIST_BITMAP_SIZE];
 } server_ctx_t;
 
 /* Initialize server context. socket_name is the abstract namespace name (e.g. "nsigner").
@@ -457,6 +463,9 @@ void server_set_prompt_always_allow(int enabled);
 /* Mark the unix listener as a trusted bridge socket (qrexec source preamble) */
 void server_set_bridge_source_trusted(server_ctx_t *ctx, int enabled);
 
+/* Set the nostr_index whitelist from a spec string ("all", "1,3,4", "0-3", "0-3,7,9") */
+int server_set_index_whitelist(server_ctx_t *ctx, const char *spec);
+
 /* Configure non-interactive prompt fallback: -1 disabled, POLICY_ALLOW, or POLICY_DENY */
 void server_set_noninteractive_prompt_default(int decision);
 
@@ -494,8 +503,8 @@ int socket_name_random(char *out, size_t out_len);
 /* Version information (auto-updated by build/version tooling) */
 #define NSIGNER_VERSION_MAJOR 0
 #define NSIGNER_VERSION_MINOR 0
-#define NSIGNER_VERSION_PATCH 34
-#define NSIGNER_VERSION "v0.0.34"
+#define NSIGNER_VERSION_PATCH 42
+#define NSIGNER_VERSION "v0.0.42"
 
 
 /* NSIGNER_HEADERLESS_DECLS_END */
@@ -799,6 +808,8 @@ static void print_usage(const char *program_name) {
     tui_print("  --mnemonic-fd N     Read mnemonic from inherited fd N (one line) at startup");
     tui_print("  --allow-all, -A     Allow all policy prompts for this server session");
     tui_print("  --bridge-source-trusted  Accept qrexec_source preamble on unix connections (bridge mode)");
+    tui_print("  --allow-index SPEC  Restrict which nostr_index values this session can access");
+    tui_print("                      SPEC: 'all' (default), '1,3,4', '0-3', or '0-3,7,9'");
 }
 
 static int extract_nsigner_socket_from_proc_line(const char *line,
@@ -1591,6 +1602,128 @@ static void apply_test_overrides(policy_table_t *policy) {
     }
 }
 
+/* Transport selection bitmask for interactive menu */
+#define TRANSPORT_UNIX          0x01
+#define TRANSPORT_QREXEC_BRIDGE 0x02
+#define TRANSPORT_TCP           0x04
+#define TRANSPORT_QREXEC_ONESHOT 0x08
+
+/*
+ * Interactive transport selection menu.
+ * Shown after mnemonic entry when no --listen flag was given and stdin is a TTY.
+ * Returns a bitmask of selected transports, or 0 on error/no selection.
+ */
+static int prompt_transport_selection(void) {
+    int selected = TRANSPORT_UNIX;  /* default: local unix socket */
+    char input[32];
+
+    for (;;) {
+        tui_render_content_screen(NULL, "Transport — how should other programs reach this signer?");
+        printf("Select one or more (type a number to toggle, 'a' for all, Enter to confirm):\n\n");
+        printf("  [%s] 1. Local Unix socket (same machine/qube)\n",
+               (selected & TRANSPORT_UNIX) ? "x" : " ");
+        printf("  [%s] 2. Qubes qrexec bridge (other qubes via qrexec, no network)\n",
+               (selected & TRANSPORT_QREXEC_BRIDGE) ? "x" : " ");
+        printf("  [%s] 3. TCP listener (FIPS mesh or local network)\n",
+               (selected & TRANSPORT_TCP) ? "x" : " ");
+        printf("\n  [a] select all    Enter = confirm\n");
+        printf("> ");
+        fflush(stdout);
+
+        if (read_line_stdin(input, sizeof(input)) != 0) {
+            return 0;
+        }
+
+        /* Trim trailing whitespace */
+        {
+            size_t len = strlen(input);
+            while (len > 0 && (input[len-1] == '\n' || input[len-1] == '\r' ||
+                               input[len-1] == ' ' || input[len-1] == '\t')) {
+                input[--len] = '\0';
+            }
+        }
+
+        if (input[0] == '\0') {
+            /* Enter pressed — confirm current selection */
+            if (selected == 0) {
+                printf("At least one transport must be selected.\n");
+                continue;
+            }
+            break;
+        }
+
+        if (input[0] == 'a' || input[0] == 'A') {
+            selected = TRANSPORT_UNIX | TRANSPORT_QREXEC_BRIDGE | TRANSPORT_TCP;
+            continue;
+        }
+
+        if (input[0] == '1') {
+            selected ^= TRANSPORT_UNIX;
+        } else if (input[0] == '2') {
+            selected ^= TRANSPORT_QREXEC_BRIDGE;
+        } else if (input[0] == '3') {
+            selected ^= TRANSPORT_TCP;
+        } else {
+            printf("Invalid input. Type 1-3, 'a', or Enter to confirm.\n");
+        }
+    }
+
+    return selected;
+}
+
+/*
+ * Interactive index whitelist prompt.
+ * Shown after transport selection when no --allow-index flag was given.
+ * Returns a malloc'd spec string (caller must free), or NULL for "all".
+ */
+static char *prompt_index_whitelist(void) {
+    char input[256];
+
+    for (;;) {
+        tui_render_content_screen(NULL, "Index whitelist — restrict which nostr_index values this session can access");
+        printf("Enter allowed indices, or press Enter for 'all' (no restriction):\n\n");
+        printf("  Examples:\n");
+        printf("    all          (default — allow all indices)\n");
+        printf("    0            (only index 0)\n");
+        printf("    0,1,3        (specific indices)\n");
+        printf("    0-3          (range 0 through 3)\n");
+        printf("    0,2-3,7      (mixed list and ranges)\n");
+        printf("\n  Enter = all\n");
+        printf("> ");
+        fflush(stdout);
+
+        if (read_line_stdin(input, sizeof(input)) != 0) {
+            return NULL;
+        }
+
+        /* Trim trailing whitespace */
+        {
+            size_t len = strlen(input);
+            while (len > 0 && (input[len-1] == '\n' || input[len-1] == '\r' ||
+                               input[len-1] == ' ' || input[len-1] == '\t')) {
+                input[--len] = '\0';
+            }
+        }
+
+        if (input[0] == '\0') {
+            /* Enter pressed — default to "all" */
+            return NULL;
+        }
+
+        /* Validate by parsing into a temp whitelist */
+        {
+            server_ctx_t tmp;
+            memset(&tmp, 0, sizeof(tmp));
+            if (server_set_index_whitelist(&tmp, input) != 0) {
+                printf("Invalid spec: '%s'. Try again or press Enter for 'all'.\n", input);
+                continue;
+            }
+        }
+
+        return strdup(input);
+    }
+}
+
 int main(int argc, char *argv[]) {
     mnemonic_state_t mnemonic;
     role_table_t role_table;
@@ -1598,13 +1731,14 @@ int main(int argc, char *argv[]) {
     policy_table_t policy;
     server_ctx_t server;
     key_store_t key_store;
-    struct pollfd pfds[2];
+    struct pollfd pfds[3];  /* max: 2 listeners (unix+tcp) + stdin */
     uid_t owner_uid;
     int derived_count;
     const char *socket_name = NSIGNER_DEFAULT_SOCKET_NAME;
     char generated_socket_name[SERVER_SOCKET_NAME_MAX];
     int socket_name_explicit = 0;
     int listen_mode = NSIGNER_LISTEN_UNIX;
+    int listen_mode_explicit = 0;
     const char *listen_target = NSIGNER_DEFAULT_SOCKET_NAME;
     int argi = 1;
     const char *preapprove_specs[POLICY_MAX_ENTRIES];
@@ -1613,6 +1747,7 @@ int main(int argc, char *argv[]) {
     int auth_skew_seconds = AUTH_DEFAULT_SKEW_SECONDS;
     int allow_all = 0;
     int bridge_source_trusted = 0;
+    const char *allow_index_spec = NULL;
     mnemonic_source_t mnemonic_source = { MNEMONIC_SOURCE_TUI, -1 };
 
     while (argi < argc) {
@@ -1633,6 +1768,7 @@ int main(int argc, char *argv[]) {
                 fprintf(stderr, "Missing value for %s\n", argv[argi]);
                 return 1;
             }
+            listen_mode_explicit = 1;
             if (strcmp(argv[argi + 1], "unix") == 0) {
                 listen_mode = NSIGNER_LISTEN_UNIX;
             } else if (strcmp(argv[argi + 1], "stdio") == 0) {
@@ -1722,6 +1858,15 @@ int main(int argc, char *argv[]) {
             argi += 1;
             continue;
         }
+        if (strcmp(argv[argi], "--allow-index") == 0) {
+            if (argi + 1 >= argc) {
+                fprintf(stderr, "Missing value for %s\n", argv[argi]);
+                return 1;
+            }
+            allow_index_spec = argv[argi + 1];
+            argi += 2;
+            continue;
+        }
         break;
     }
 
@@ -1853,6 +1998,59 @@ int main(int argc, char *argv[]) {
 
     dispatcher_init(&dispatcher, &role_table, &mnemonic, &key_store);
 
+    /*
+     * Interactive transport selection: if no --listen flag was given and
+     * stdin is a TTY, show the multi-select transport menu. This lets the
+     * user choose how other programs reach the signer without memorizing
+     * CLI flags. CLI flags skip the menu (backward compatible).
+     */
+    int transport_mask = 0;
+    int multi_listen = 0;  /* set when multiple persistent listeners are active */
+    server_ctx_t servers[2];  /* max: unix + tcp */
+    int server_count = 0;
+    int unix_server_idx = -1;
+    int tcp_server_idx = -1;
+
+    if (!listen_mode_explicit && isatty(STDIN_FILENO) &&
+        mnemonic_source.kind == MNEMONIC_SOURCE_TUI) {
+        transport_mask = prompt_transport_selection();
+        if (transport_mask == 0) {
+            fprintf(stderr, "No transport selected. Exiting.\n");
+            crypto_wipe(&key_store);
+            nostr_cleanup();
+            mnemonic_unload(&mnemonic);
+            return 1;
+        }
+
+        /* Index whitelist prompt (only if --allow-index wasn't given on CLI) */
+        if (allow_index_spec == NULL) {
+            char *wl_spec = prompt_index_whitelist();
+            if (wl_spec != NULL) {
+                allow_index_spec = wl_spec;  /* will be freed at program exit */
+            }
+        }
+
+        /* Persistent listeners — configure from menu selection */
+        multi_listen = 1;
+
+        /* Unix socket (with or without bridge-source-trusted) */
+        if (transport_mask & (TRANSPORT_UNIX | TRANSPORT_QREXEC_BRIDGE)) {
+            /* Use fixed name "nsigner" for scripted access */
+            socket_name = "nsigner";
+            socket_name_explicit = 1;
+            listen_mode = NSIGNER_LISTEN_UNIX;
+            listen_target = socket_name;
+            if (transport_mask & TRANSPORT_QREXEC_BRIDGE) {
+                bridge_source_trusted = 1;
+            }
+        }
+
+        /* TCP listener */
+        if (transport_mask & TRANSPORT_TCP) {
+            /* Will be started as a second listener */
+        }
+    }
+
     if (listen_mode == NSIGNER_LISTEN_UNIX && !socket_name_explicit) {
         if (socket_name_random(generated_socket_name, sizeof(generated_socket_name)) != 0) {
             fprintf(stderr, "Failed to generate random socket name\n");
@@ -1898,6 +2096,16 @@ int main(int argc, char *argv[]) {
    if (bridge_source_trusted) {
        server_set_bridge_source_trusted(&server, 1);
    }
+   if (allow_index_spec != NULL) {
+       if (server_set_index_whitelist(&server, allow_index_spec) != 0) {
+           fprintf(stderr, "Invalid --allow-index spec: %s\n", allow_index_spec);
+           fprintf(stderr, "Expected: 'all', '1,3,4', '0-3', or '0-3,7,9'\n");
+           crypto_wipe(&key_store);
+           nostr_cleanup();
+           mnemonic_unload(&mnemonic);
+           return 1;
+       }
+   }
    if (server_start(&server) != 0) {
         if (listen_mode == NSIGNER_LISTEN_UNIX) {
             fprintf(stderr, "Failed to start server on @%s: %s\n", socket_name, server_last_error(&server));
@@ -1914,6 +2122,44 @@ int main(int argc, char *argv[]) {
         return 1;
     }
 
+    /*
+     * Multi-listener: if interactive menu selected TCP in addition to unix,
+     * start a second server context for TCP. The primary server (unix) is
+     * already running. Both share the same dispatcher and policy.
+     */
+    if (multi_listen && (transport_mask & TRANSPORT_TCP)) {
+        const char *tcp_target = "tcp:[::]:8080";
+        tcp_server_idx = server_count;
+        server_init(&servers[tcp_server_idx],
+                    tcp_target,
+                    0,  /* socket_name_explicit = 0 for TCP */
+                    NSIGNER_LISTEN_TCP,
+                    NSIGNER_AUTH_REQUIRED,
+                    auth_skew_seconds,
+                    &dispatcher,
+                    &policy);
+        if (allow_index_spec != NULL) {
+            server_set_index_whitelist(&servers[tcp_server_idx], allow_index_spec);
+        }
+        if (server_start(&servers[tcp_server_idx]) != 0) {
+            fprintf(stderr, "Failed to start TCP server on %s: %s\n",
+                    tcp_target, server_last_error(&servers[tcp_server_idx]));
+            server_stop(&server);
+            crypto_wipe(&key_store);
+            nostr_cleanup();
+            mnemonic_unload(&mnemonic);
+            return 1;
+        }
+        server_count++;
+    }
+
+    /* Copy the primary (unix) server into the array for unified polling */
+    if (multi_listen) {
+        unix_server_idx = server_count;
+        servers[unix_server_idx] = server;  /* struct copy */
+        server_count++;
+    }
+
     (void)signal(SIGINT, handle_signal);
     (void)signal(SIGTERM, handle_signal);
     /*
@@ -1935,7 +2181,22 @@ int main(int argc, char *argv[]) {
 
         connection_info_clear();
 
-        if (listen_mode == NSIGNER_LISTEN_UNIX) {
+        if (multi_listen) {
+            /* Multi-listener mode: show all active transports */
+            if (transport_mask & (TRANSPORT_UNIX | TRANSPORT_QREXEC_BRIDGE)) {
+                if (bridge_source_trusted) {
+                    connection_info_add("listen: unix @%s (bridge-source-trusted)", socket_name);
+                } else {
+                    connection_info_add("listen: unix @%s", socket_name);
+                }
+                connection_info_add("client: nsigner --socket-name %s client '<json>'", socket_name);
+                printf("System is ready and waiting for connections on @%s.\n", socket_name);
+            }
+            if (transport_mask & TRANSPORT_TCP) {
+                connection_info_add("listen: tcp [::]:8080");
+                printf("System is ready and waiting for connections on tcp:[::]:8080.\n");
+            }
+        } else if (listen_mode == NSIGNER_LISTEN_UNIX) {
             connection_info_add("listen: unix @%s", socket_name);
             connection_info_add("client: nsigner --socket-name %s client '<json>'", socket_name);
             printf("System is ready and waiting for connections on @%s.\n", socket_name);
@@ -2013,13 +2274,26 @@ int main(int argc, char *argv[]) {
         tui_install_resize_handler();
         render_status(&role_table, &mnemonic, derived_count, socket_name);
 
-        pfds[0].fd = server.listen_fd;
-        pfds[0].events = POLLIN;
-        pfds[1].fd = STDIN_FILENO;
-        pfds[1].events = POLLIN;
+        /* Set up poll fds: listener(s) + stdin */
+        int npfds = 0;
+        if (multi_listen) {
+            for (int si = 0; si < server_count; si++) {
+                pfds[npfds].fd = servers[si].listen_fd;
+                pfds[npfds].events = POLLIN;
+                npfds++;
+            }
+        } else {
+            pfds[npfds].fd = server.listen_fd;
+            pfds[npfds].events = POLLIN;
+            npfds++;
+        }
+        pfds[npfds].fd = STDIN_FILENO;
+        pfds[npfds].events = POLLIN;
+        npfds++;
+        int stdin_pfd_idx = npfds - 1;
 
         while (g_running && server.running) {
-            int prc = poll(pfds, 2, 200);
+            int prc = poll(pfds, npfds, 200);
             if (prc < 0) {
                 if (errno == EINTR) {
                     continue;
@@ -2031,15 +2305,31 @@ int main(int argc, char *argv[]) {
                 render_status(&role_table, &mnemonic, derived_count, socket_name);
             }
 
-            if (prc > 0 && (pfds[0].revents & POLLIN)) {
+            /* Check all listener fds for activity */
+            if (prc > 0) {
+                if (multi_listen) {
+                    for (int si = 0; si < server_count; si++) {
+                        if (pfds[si].revents & POLLIN) {
+                            int hrc = server_handle_one(&servers[si], activity_log_cb, NULL);
+                            if (hrc < 0) {
+                                g_running = 0;
+                                break;
+                            }
+                            render_status(&role_table, &mnemonic, derived_count, socket_name);
+                        }
+                    }
+                } else {
+                    if (pfds[0].revents & POLLIN) {
                         int hrc = server_handle_one(&server, activity_log_cb, NULL);
                         if (hrc < 0) {
                             break;
                         }
                         render_status(&role_table, &mnemonic, derived_count, socket_name);
                     }
+                }
+            }
 
-            if (prc > 0 && (pfds[1].revents & POLLIN)) {
+            if (prc > 0 && (pfds[stdin_pfd_idx].revents & POLLIN)) {
                 char ch = '\0';
                 if (read(STDIN_FILENO, &ch, 1) > 0) {
                     char lower = (char)tolower((unsigned char)ch);
@@ -2083,7 +2373,13 @@ int main(int argc, char *argv[]) {
         server_set_approval_cb(NULL, NULL);
     }
 
+    if (multi_listen) {
+        for (int si = 0; si < server_count; si++) {
+            server_stop(&servers[si]);
+        }
+    } else {
         server_stop(&server);
+    }
     crypto_wipe(&key_store);
     nostr_cleanup();
     mnemonic_unload(&mnemonic);

src/server.c

@@ -415,6 +415,9 @@ typedef struct {
 } caller_identity_t;
 
 /* Server context */
+#define INDEX_WHITELIST_MAX 256  /* nostr_index range 0-255 */
+#define INDEX_WHITELIST_BITMAP_SIZE (INDEX_WHITELIST_MAX / 8)  /* 32 bytes */
+
 typedef struct {
     char socket_name[SERVER_SOCKET_NAME_MAX]; /* abstract namespace name (without \0 prefix) */
     char last_error[256];
@@ -428,6 +431,8 @@ typedef struct {
     int auth_mode;
     int auth_skew_seconds;
     int bridge_source_trusted;  /* when set, unix connections send a qrexec_source preamble */
+    int index_whitelist_active;  /* 1 if index whitelist is set (not "all") */
+    unsigned char index_whitelist[INDEX_WHITELIST_BITMAP_SIZE];  /* bitmap of allowed nostr_index values */
 } server_ctx_t;
 
 /* Initialize server context. socket_name is the abstract namespace name (e.g. "nsigner").
@@ -444,6 +449,15 @@ void server_init(server_ctx_t *ctx, const char *socket_name, int socket_name_exp
  * identity is composed as qubes:<vm>. */
 void server_set_bridge_source_trusted(server_ctx_t *ctx, int enabled);
 
+/* Set the nostr_index whitelist from a parsed spec string.
+ * Spec format: "all" (no restriction), or comma-separated list of
+ * indices and ranges, e.g. "1,3,4" or "0-3" or "0-3,7,9".
+ * Returns 0 on success, -1 on parse error. */
+int server_set_index_whitelist(server_ctx_t *ctx, const char *spec);
+
+/* Check if a nostr_index is in the whitelist. Returns 1 if allowed, 0 if not. */
+int server_index_whitelist_allows(const server_ctx_t *ctx, int nostr_index);
+
 /* Start listening. Returns 0 on success, -1 on error. */
 int server_start(server_ctx_t *ctx);
 
@@ -1058,6 +1072,8 @@ void server_init(server_ctx_t *ctx, const char *socket_name, int socket_name_exp
     ctx->auth_mode = auth_mode;
     ctx->auth_skew_seconds = (auth_skew_seconds > 0) ? auth_skew_seconds : AUTH_DEFAULT_SKEW_SECONDS;
     ctx->bridge_source_trusted = 0;
+    ctx->index_whitelist_active = 0;
+    memset(ctx->index_whitelist, 0, sizeof(ctx->index_whitelist));
     if (!g_auth_nonce_cache_inited) {
         auth_nonce_cache_init(&g_auth_nonce_cache);
         g_auth_nonce_cache_inited = 1;
@@ -1071,6 +1087,87 @@ void server_set_bridge_source_trusted(server_ctx_t *ctx, int enabled) {
     ctx->bridge_source_trusted = enabled ? 1 : 0;
 }
 
+static void whitelist_set_bit(unsigned char *bitmap, int index) {
+    if (index >= 0 && index < INDEX_WHITELIST_MAX) {
+        bitmap[index / 8] |= (1 << (index % 8));
+    }
+}
+
+static int whitelist_get_bit(const unsigned char *bitmap, int index) {
+    if (index < 0 || index >= INDEX_WHITELIST_MAX) {
+        return 0;
+    }
+    return (bitmap[index / 8] >> (index % 8)) & 1;
+}
+
+int server_set_index_whitelist(server_ctx_t *ctx, const char *spec) {
+    char buf[256];
+    char *p;
+    char *token;
+
+    if (ctx == NULL || spec == NULL) {
+        return -1;
+    }
+
+    /* "all" means no restriction */
+    if (strcmp(spec, "all") == 0) {
+        ctx->index_whitelist_active = 0;
+        memset(ctx->index_whitelist, 0, sizeof(ctx->index_whitelist));
+        return 0;
+    }
+
+    strncpy(buf, spec, sizeof(buf) - 1);
+    buf[sizeof(buf) - 1] = '\0';
+
+    /* Parse comma-separated entries: "1,3,4" or "0-3" or "0-3,7,9" */
+    memset(ctx->index_whitelist, 0, sizeof(ctx->index_whitelist));
+    p = buf;
+    while (p != NULL && *p != '\0') {
+        char *comma = strchr(p, ',');
+        if (comma != NULL) {
+            *comma = '\0';
+        }
+
+        /* Parse token: either "N" or "N-M" (range) */
+        char *dash = strchr(p, '-');
+        if (dash != NULL) {
+            *dash = '\0';
+            char *endptr1 = NULL, *endptr2 = NULL;
+            long lo = strtol(p, &endptr1, 10);
+            long hi = strtol(dash + 1, &endptr2, 10);
+            if (*endptr1 != '\0' || *endptr2 != '\0' || lo < 0 || hi < 0 ||
+                lo >= INDEX_WHITELIST_MAX || hi >= INDEX_WHITELIST_MAX || lo > hi) {
+                return -1;
+            }
+            for (long i = lo; i <= hi; i++) {
+                whitelist_set_bit(ctx->index_whitelist, (int)i);
+            }
+        } else {
+            char *endptr = NULL;
+            long idx = strtol(p, &endptr, 10);
+            if (*endptr != '\0' || idx < 0 || idx >= INDEX_WHITELIST_MAX) {
+                return -1;
+            }
+            whitelist_set_bit(ctx->index_whitelist, (int)idx);
+        }
+
+        p = (comma != NULL) ? comma + 1 : NULL;
+    }
+
+    ctx->index_whitelist_active = 1;
+    return 0;
+}
+
+int server_index_whitelist_allows(const server_ctx_t *ctx, int nostr_index) {
+    if (ctx == NULL) {
+        return 1;  /* no ctx = allow (shouldn't happen) */
+    }
+    if (!ctx->index_whitelist_active) {
+        return 1;  /* "all" mode = no restriction */
+    }
+    return whitelist_get_bit(ctx->index_whitelist, nostr_index);
+}
+
 int server_start(server_ctx_t *ctx) {
     int fd;
     struct sockaddr_un addr;
@@ -1569,6 +1666,24 @@ int server_handle_one(server_ctx_t *ctx, server_activity_cb cb, void *cb_data) {
         }
     }
 
+    /*
+     * Index whitelist enforcement: if the request specifies a nostr_index
+     * and the whitelist is active (not "all"), check that the index is
+     * allowed. This is a hard deny — it happens before policy/approval,
+     * so even an approved caller cannot access a non-whitelisted index.
+     * We set hard_selector_error to a sentinel so the policy_check branch
+     * is skipped.
+     */
+    if (hard_selector_error == 0 && selector_req.has_nostr_index &&
+        !server_index_whitelist_allows(ctx, selector_req.nostr_index)) {
+        (void)snprintf(role_name, sizeof(role_name), "nostr_idx_%d", selector_req.nostr_index);
+        response = strdup("{\"id\":\"null\",\"error\":{\"code\":2002,\"message\":\"index_not_allowed\"}}");
+        pchk = POLICY_DENY;
+        verdict = "DENIED";
+        source_label = "index-not-approved";
+        hard_selector_error = -100;  /* sentinel: skip policy_check */
+    }
+
     if (hard_selector_error == SELECTOR_ERR_AMBIGUOUS) {
         response = strdup("{\"id\":\"null\",\"error\":{\"code\":1001,\"message\":\"ambiguous_role_selector\"}}");
         pchk = POLICY_DENY;
@@ -1578,9 +1693,11 @@ int server_handle_one(server_ctx_t *ctx, server_activity_cb cb, void *cb_data) {
     } else if (hard_selector_error == SELECTOR_ERR_NOT_FOUND) {
         response = strdup("{\"id\":\"null\",\"error\":{\"code\":1002,\"message\":\"unknown_role\"}}");
         pchk = POLICY_DENY;
-    } else {
+    } else if (hard_selector_error == 0) {
+        /* Normal path: run policy_check (skip if whitelist already denied) */
         pchk = policy_check(ctx->policy, caller.caller_id, method, role_name, purpose, &policy_src);
     }
+    /* else: hard_selector_error == -100 (whitelist deny) — keep pchk=POLICY_DENY */
 
     if (pchk == POLICY_PROMPT) {
         pchk = prompt_for_policy_decision(&caller, method, role_name, purpose, pending_derivation);
@@ -1661,6 +1778,9 @@ int server_handle_one(server_ctx_t *ctx, server_activity_cb cb, void *cb_data) {
         source_label = "session-grant";
     } else if (pchk == POLICY_ALLOW) {
         source_label = "prompt";
+    } else if (hard_selector_error == -100) {
+        /* Index whitelist denial — keep the label set by the whitelist check */
+        /* source_label already set to "index-not-approved" above */
     } else {
         source_label = "no-match";
     }