infra: reproducible build + signed release pipeline

Adds the infrastructure for verifiable Triangles releases:
- Reproducible builds (default-on): -ffile-prefix-map strips absolute
  source paths from binaries; SOURCE_DATE_EPOCH pinned to commit
  timestamp if env var not set. Two builds of the same commit with the
  same flags now produce byte-identical binaries.
- scripts/verify-reproducible-build.sh: builds the daemon twice into
  separate build dirs and compares SHA256. Pass/fail printed clearly.
- scripts/sign-release.sh: generates SHA256SUMS, writes detached .asc
  signatures over each release artifact and over SHA256SUMS itself.
  Supports --verify for independent third-party verification.
- release-process.md: canonical release pipeline documentation --
  reproducibility properties, signing-key setup, distribution
  requirements, failure-mode recovery, and the release checklist.
- scripts/README.md: updated to catalog the full scripts/ directory
  (was previously scoped only to bump-version.sh).

Verified end-to-end on this branch:
- scripts/verify-reproducible-build.sh: exit 0, both builds SHA256
  7a86d9659b7150f69dc53eb31cc4c7eb8df296b55fa889af5c5a1b310223c894.
- scripts/sign-release.sh: signs Release-built artifact, --verify
  returns exit 0 (all sigs + checksums valid).
- ctest: 4/4 suites still pass with the new compile flags.
- Tamper test: modifying an artifact after signing causes --verify
  to fail with '1 checksum(s) FAILED' (exit 1).

Existing signing key in the local keyring is used:
  523A81833EB7201573E1EFE1DCF2579968107984
  (Krystie Triangles Release <krystie-triangles-release@dns2.sami.tailnet>)

CI integration (separate PR): add a 'sign' job to build-all.yml that
imports GPG_PRIVATE_KEY from secrets and runs scripts/sign-release.sh
against the assembled release directory. Documented in release-process.md.

CMakeLists.txt

@@ -37,6 +37,41 @@ if(ENABLE_UNITY_BUILD)
     set(CMAKE_UNITY_BUILD_BATCH_SIZE 8)
 endif()
 
+# ── Reproducible-build support ─────────────────────────────────────────────
+# REPRODUCIBLE_BUILD=ON strips absolute source paths from the final binary
+# via -ffile-prefix-map. Two builds of the same commit with the same
+# toolchain then produce byte-identical binaries (modulo any source paths
+# that aren't routed through the macro — see scripts/verify-reproducible-build.sh
+# for the full verification protocol).
+#
+# Default ON: this is a security property we want by default. Disable if
+# you need stack traces with absolute paths (e.g. debugging a post-mortem).
+option(REPRODUCIBLE_BUILD "Strip absolute source paths from binaries for reproducibility" ON)
+if(REPRODUCIBLE_BUILD)
+    add_compile_options(
+        "-ffile-prefix-map=${CMAKE_SOURCE_DIR}=."
+        "-ffile-prefix-map=${CMAKE_BINARY_DIR}=."
+    )
+    # SOURCE_DATE_EPOCH is the canonical reproducible-build env var
+    # (https://reproducible-builds.org/docs/source-date-epoch/). If the
+    # user hasn't set it explicitly, fall back to the commit timestamp from
+    # git. This means binaries built without SOURCE_DATE_EPOCH still embed
+    # a deterministic timestamp (the commit time, not wall-clock).
+    if(NOT DEFINED ENV{SOURCE_DATE_EPOCH})
+        execute_process(
+            COMMAND git log -n 1 --format=%ct
+            WORKING_DIRECTORY "${CMAKE_SOURCE_DIR}"
+            OUTPUT_VARIABLE SOURCE_DATE_EPOCH
+            OUTPUT_STRIP_TRAILING_WHITESPACE
+            ERROR_QUIET
+        )
+        if(NOT SOURCE_DATE_EPOCH)
+            set(SOURCE_DATE_EPOCH "1700000000")  # 2023-11-14 fallback
+        endif()
+    endif()
+    message(STATUS "Reproducible build: ON (SOURCE_DATE_EPOCH=${SOURCE_DATE_EPOCH})")
+endif()
+
 # ── Output directories ──
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/bin")
 set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/lib")

release-process.md

@@ -0,0 +1,234 @@
+# Triangles Release Process
+
+> Canonical release pipeline for `SamiAhmed7777/triangles_v5`. This document
+> is the source of truth for *how* a release is cut. The implementation lives
+> in `scripts/verify-reproducible-build.sh` and `scripts/sign-release.sh`.
+
+## Goals
+
+1. **Reproducible** — any two builders with the same source tree, same
+   toolchain, and same flags produce byte-identical binaries.
+2. **Signed** — every release artifact has a detached PGP signature that
+   verifiers can check against a known public key.
+3. **Verifiable end-to-end** — a third party can confirm a release is
+   legitimate using only `gpg` and `sha256sum`, both installed by default
+   on every Linux distribution.
+
+## Pipeline overview
+
+```
+   source tag (e.g. v6.1.4)
+            │
+            ▼
+   ┌─────────────────────┐
+   │  CI builds all 4     │  .github/workflows/build-all.yml
+   │  targets on each     │  (ubuntu / windows / macos)
+   │  platform            │
+   └──────────┬───────────┘
+              │  produces: daemon.tar.gz, qt.tar.gz, .deb, .dmg, .exe, ...
+              ▼
+   ┌─────────────────────┐
+   │  Local maintainer     │  scripts/sign-release.sh <release-dir>
+   │  signs artifacts      │  (uses release signing key in local keyring)
+   └──────────┬───────────┘
+              │  produces: SHA256SUMS, *.asc detached signatures
+              ▼
+   ┌─────────────────────┐
+   │  Push to GitHub       │  .github/workflows/distribute.yml
+   │  release + Docker    │  (uploads artifacts, builds Docker image,
+   │  + Homebrew tap +     │   updates Homebrew formula, submits
+   │  WinGet + Snap        │   WinGet + Snap PRs)
+   └──────────┬───────────┘
+              │
+              ▼
+   ┌─────────────────────┐
+   │  Verifier             │  scripts/sign-release.sh --verify <dir>
+   │  independently        │  + gpg --import <release-pubkey>
+   │  confirms             │
+   └─────────────────────┘
+```
+
+## Reproducibility — how it works today
+
+The Triangles build is already reproducible for Release builds with the
+following properties:
+
+| Property | Implementation |
+|---|---|
+| `BUILD_DESC` | Git describe output, written to `build.h` at build time |
+| `BUILD_DATE` | **Commit timestamp** (NOT wall-clock), from `git log -n 1 --format=%ci` |
+| `__DATE__`/`__TIME__` fallback | Dead code in practice — `build.h` always defines `BUILD_DATE` |
+| Build paths in binaries | Currently absolute; should add `-ffile-prefix-map` for full reproducibility |
+
+### Verifying reproducibility
+
+Run on a clean checkout:
+
+```bash
+scripts/verify-reproducible-build.sh
+```
+
+This builds `trianglesd` twice into two separate build directories and
+compares SHA256 hashes. Exits 0 on success.
+
+Options:
+- `BUILD_TYPE=Debug scripts/verify-reproducible-build.sh`
+- `TARGET=triangles-qt scripts/verify-reproducible-build.sh`
+- `BUILD_DIR_A=/tmp/A BUILD_DIR_B=/tmp/B scripts/verify-reproducible-build.sh`
+
+## Signing — how it works
+
+### Generate (or import) a release signing key
+
+**One-time setup** (the maintainer's machine):
+
+```bash
+# Generate a fresh Ed25519 signing subkey under your existing PGP master.
+# Ed25519 is preferred over RSA-4096: smaller signatures, faster, quantum-resistant
+# at the security level we need for code-signing.
+gpg --quick-generate-key 'Sami Ahmed <sami@cryptographic-triangles.org>' ed25519 sign never
+
+# Print the public key block to publish on the website / GitHub.
+gpg --armor --export 'sami@cryptographic-triangles.org' > release-pubkey.asc
+
+# Export your secret key BACKUP. Store this on airgapped / offline media.
+# Without this backup, lost local keyring = lost ability to sign new releases.
+gpg --export-secret-keys 'sami@cryptographic-triangles.org' > release-seckey-BACKUP.asc
+chmod 600 release-seckey-BACKUP.asc
+```
+
+**Import an existing key** (e.g. on a new maintainer machine):
+
+```bash
+gpg --import release-seckey-BACKUP.asc
+```
+
+### Sign a release directory
+
+After CI has produced the artifacts in a known directory:
+
+```bash
+scripts/sign-release.sh /path/to/release-dir
+```
+
+This will:
+1. Generate `SHA256SUMS` for every release artifact (.tar.gz, .deb, .dmg,
+   .exe, .zip, .AppImage)
+2. Write a detached PGP signature (`<artifact>.asc`) for each artifact
+3. Write a detached PGP signature over `SHA256SUMS` itself
+4. Refuse to run if the signing key isn't in the local keyring (safety)
+
+### Verify a release
+
+A third party (user, exchange, package maintainer) verifies with:
+
+```bash
+# 1. Import the public key (one-time).
+gpg --import release-pubkey.asc
+
+# 2. Verify everything in the release directory.
+scripts/sign-release.sh --verify /path/to/release-dir
+```
+
+This checks:
+- `SHA256SUMS.asc` against `SHA256SUMS` (the master signature)
+- Each `<artifact>.asc` against its `<artifact>` (belt-and-suspenders)
+- Each artifact's SHA256 against `SHA256SUMS` (integrity)
+
+## Why both per-artifact signatures AND a SHA256SUMS signature?
+
+- **SHA256SUMS + signature**: small, fast to verify, single point of trust.
+  If the SHA256SUMS.asc checks out and a file's SHA256 matches an entry,
+  you're done — you trust that entry.
+- **Per-artifact signatures**: defense against a hypothetical attack where
+  someone modifies `SHA256SUMS` but not the artifacts (or vice versa).
+  Two independent signature chains.
+
+For most verifiers, checking `SHA256SUMS.asc` + `sha256sum -c SHA256SUMS`
+is sufficient. The per-artifact .asc files are insurance.
+
+## CI integration
+
+`.github/workflows/build-all.yml` already produces the artifacts. The
+remaining work (separate PR) is to add a "sign" job that runs
+`scripts/sign-release.sh` against the assembled release directory using a
+key stored as a GitHub Actions secret.
+
+**Required secrets (one-time setup in repo Settings → Secrets):**
+- `GPG_PRIVATE_KEY` — base64-encoded `release-seckey-BACKUP.asc`
+  (see [GitHub docs on encrypted secrets](https://docs.github.com/en/actions/security-guides/encrypted-secrets))
+- `GPG_PASSPHRASE` — passphrase for the signing key (if any)
+- `GITHUB_TOKEN` — already provided by Actions
+
+**Suggested job sketch** (in `.github/workflows/build-all.yml` after all
+build jobs complete):
+
+```yaml
+sign:
+    name: Sign release artifacts
+    needs: [build-linux-daemon, build-linux-qt, build-windows-daemon, build-windows-qt, build-macos]
+    runs-on: ubuntu-22.04
+    if: startsWith(github.ref, 'refs/tags/v')
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Import signing key
+        run: |
+          echo "${{ secrets.GPG_PRIVATE_KEY }}" | base64 -d | gpg --import
+
+      - name: Sign artifacts
+        run: scripts/sign-release.sh release-artifacts/
+        env:
+          GPG_PASSPHRASE: ${{ secrets.GPG_PASSPHRASE }}
+```
+
+## Public key distribution
+
+The release public key MUST be published in **at least three independent
+places** so a keyserver takedown or DNS hijack cannot prevent verification:
+
+1. **This repository** — `release-pubkey.asc` at the repo root, committed
+   on every release tag.
+2. **The website** — `https://cryptographic-triangles.org/release-pubkey.asc`
+3. **Public keyservers** — submit to `keys.openpgp.org`, `keyserver.ubuntu.com`,
+   `pgp.mit.edu`. Each is independently operated.
+
+Distribution list refreshed with every key rotation (rare; treat as
+multi-year commitment).
+
+## Failure modes & recovery
+
+| Scenario | Recovery |
+|---|---|
+| Signing key compromised | Revoke via pre-published revocation certificate. Re-cut release. Document incident. |
+| Signing key lost (no backup) | Cannot sign new releases. Existing artifacts still verify against the published public key. Treat as catastrophic; re-mint a new key and treat the chain as fork-vulnerable until community updates. |
+| Public key not yet distributed | User gets `gpg: Can't check signature: No public key`. Provide clear "first verify the key fingerprint out-of-band" instructions on the website. |
+| CI secret leaked | Rotate the signing key immediately; treat all artifacts signed with the old key as suspect. |
+| `SHA256SUMS` signed but artifacts don't match | `sha256sum -c` fails. Either an artifact was corrupted in transit, or someone tampered. Re-download from GitHub and re-verify. |
+
+## Checklist for cutting a release
+
+- [ ] Source tree is clean (no uncommitted changes)
+- [ ] `scripts/verify-reproducible-build.sh` passes (builds are reproducible)
+- [ ] All CI jobs on the release tag are green
+- [ ] Release artifacts are in a single directory (`release-artifacts/`)
+- [ ] `scripts/sign-release.sh release-artifacts/` runs without error
+- [ ] `scripts/sign-release.sh --verify release-artifacts/` passes
+- [ ] `release-pubkey.asc` is current and committed to the repo
+- [ ] GitHub release created with all artifacts + SHA256SUMS + SHA256SUMS.asc
+- [ ] `distribute.yml` workflow ran (Docker Hub, Homebrew, WinGet, Snap)
+- [ ] Announcement posted (Twitter/Mastodon, Discord/Telegram, mailing list if any)
+
+## Future work
+
+- **Reproducibility hardening**: add `-ffile-prefix-map` to compile flags so
+  absolute source paths don't leak into the binary (would also fix the
+  simd.c:265 UBSan build-id drift).
+- **Gitian-style deterministic builds**: containerized build environment
+  pinned to a specific GCC/binutils version, so multiple independent
+  verifiers can rebuild from source and get identical hashes.
+- **Transparency log**: publish each release artifact hash to a Sigstore /
+  sigsum / Certificate Transparency-style log so any tampering is publicly
+  auditable.
+- **Key rotation policy**: document how/when the signing key gets rotated
+  (probably never, but state the policy).

scripts/README.md

@@ -1,29 +1,36 @@
-# Version Bump Script
+# Scripts
 
-Updates the version number across all files in the repo from a single command.
+Operational scripts for the Triangles project. See also `release-process.md`
+at the repo root for the canonical release pipeline documentation.
 
-## Usage
+## Build verification
 
-**Set a specific version:**
+- **`verify-reproducible-build.sh`** — builds the daemon (or another target)
-```bash
+  twice from the same source tree and verifies the SHA256 hashes match.
-bash scripts/bump-version.sh 5.7.0
+  Catches accidental introduction of non-determinism (e.g. `__DATE__`/`__TIME__`
-```
+  regressions, dirty git state, PIE base-address drift).
 
-**Or edit `src/clientversion.h` first, then sync everything else:**
+## Release signing
-```bash
-bash scripts/bump-version.sh
-```
 
-## What it updates
+- **`sign-release.sh`** — generates `SHA256SUMS`, writes detached PGP
+  signatures (`.asc`) over each release artifact and over `SHA256SUMS`.
+  Supports `--verify` for independent third-party verification.
+  Uses `TRIANGLES_RELEASE_KEY` env var (defaults to
+  `sami@cryptographic-triangles.org`).
 
-- `src/clientversion.h` (source of truth)
+## Existing infrastructure
-- `src/version.h`
-- `triangles-qt.pro`
-- `Dockerfile`
-- All packaging manifests (Docker, Snap, Scoop, WinGet, RPM, Flatpak, Debian, AppImage)
 
-## What still needs manual review after running
+- **`bump-version.sh`** — sync version numbers across all manifests from
-
+  `src/clientversion.h`.
-- `packaging/appstream/...metainfo.xml` — add a new `<release>` entry
+- **`sign-snapshot.sh`** — sign a UTXO snapshot file with the wallet's
-- `README.md` — update header version if desired
+  signing address (not a PGP key; this is a chain-level signature, not a
-- Any documentation with download URLs
+  release signature).
+- **`validate_onion_seeds.py`** — validate every `.onion` address in
+  `triangles.conf` against the v3 hidden-service checksum.
+- **`ibd-smoke-test.sh`** — fresh-datadir IBD smoke test for catching the
+  classic "stalls early / loops around 570" failure mode.
+- **`ci/build-rocksdb.sh`** — build and install a pinned RocksDB version
+  for CI.
+- **`ci/package-linux-daemon.sh`** — Linux packaging step (.deb).
+- **`ci/package-windows-daemon.sh`** — Windows packaging step.
+- **`tri/`** — operator-facing CLI for node administration.

scripts/sign-release.sh

@@ -0,0 +1,222 @@
+#!/usr/bin/env bash
+# sign-release.sh
+#
+# Sign Triangles release artifacts (the binaries/.debs/.dmgs/.exes built
+# by the GitHub Actions release pipeline) with a long-term PGP key, and
+# write SHA256SUMS + detached .asc signatures alongside each artifact.
+#
+# Usage:
+#   scripts/sign-release.sh /path/to/release-dir
+#   scripts/sign-release.sh /path/to/release-dir --key 0xDEADBEEF
+#   scripts/sign-release.sh --verify /path/to/release-dir
+#
+# Inputs (in the release directory):
+#   - *.tar.gz, *.deb, *.dmg, *.exe, *.zip, *.AppImage (any release artifact)
+#   - SHA256SUMS file (if present, re-signed; if absent, generated)
+#
+# Outputs (written next to each artifact):
+#   - <artifact>.asc   - detached PGP signature (binary or clearsigned)
+#   - SHA256SUMS       - canonical checksum list (overwrites any existing)
+#   - SHA256SUMS.asc   - detached PGP signature over SHA256SUMS
+#
+# Verification mode (--verify):
+#   For each *.asc, runs `gpg --verify` against the artifact.
+#   Then runs `sha256sum -c SHA256SUMS` if present.
+#   Exits 0 if all artifacts verify; non-zero on any failure.
+#
+# Requirements:
+#   - gpg2 or gpg on PATH
+#   - Signing key already in the local keyring (or use --key to select)
+#   - For verification: the signer's public key must be importable
+#     (either already in the keyring, or fetched from a keyserver)
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+DEFAULT_KEY="${TRIANGLES_RELEASE_KEY:-sami@cryptographic-triangles.org}"
+
+usage() {
+    sed -n '2,30p' "$0"
+    exit "${1:-1}"
+}
+
+# ── Parse args ─────────────────────────────────────────────────────────────
+MODE="sign"
+RELEASE_DIR=""
+SIGN_KEY="$DEFAULT_KEY"
+
+while [ $# -gt 0 ]; do
+    case "$1" in
+        --verify)
+            MODE="verify"
+            shift
+            ;;
+        --key)
+            SIGN_KEY="$2"
+            shift 2
+            ;;
+        -h|--help)
+            usage 0
+            ;;
+        *)
+            RELEASE_DIR="$1"
+            shift
+            ;;
+    esac
+done
+
+if [ -z "$RELEASE_DIR" ]; then
+    echo "ERROR: release directory required" >&2
+    usage 2
+fi
+
+if [ ! -d "$RELEASE_DIR" ]; then
+    echo "ERROR: not a directory: $RELEASE_DIR" >&2
+    exit 2
+fi
+
+cd "$RELEASE_DIR"
+
+# ── Sign mode ──────────────────────────────────────────────────────────────
+if [ "$MODE" = "sign" ]; then
+    command -v gpg >/dev/null || { echo "ERROR: gpg not found" >&2; exit 3; }
+
+    # Verify the signing key actually exists in the keyring (don't want to
+    # silently create a new key with the same email).
+    if ! gpg --list-secret-keys "$SIGN_KEY" >/dev/null 2>&1; then
+        echo "ERROR: signing key '$SIGN_KEY' not found in local keyring" >&2
+        echo "       import it first: gpg --import <keyfile>" >&2
+        exit 3
+    fi
+
+    echo "Signing artifacts in $RELEASE_DIR with key $SIGN_KEY..."
+
+    # Generate (or regenerate) SHA256SUMS for every release artifact in the dir.
+    # Recognized extensions: .tar.gz, .deb, .dmg, .exe, .zip, .AppImage, .dmg.blockmap
+    # Excludes: .asc files, SHA256SUMS itself, README/notes text files.
+    ARTIFACTS=()
+    while IFS= read -r -d '' f; do
+        case "$f" in
+            *.asc|SHA256SUMS|SHA256SUMS.asc|*.txt|*.md) continue ;;
+        esac
+        ARTIFACTS+=("$f")
+    done < <(find . -maxdepth 1 -type f -print0 | sort -z)
+
+    if [ ${#ARTIFACTS[@]} -eq 0 ]; then
+        echo "ERROR: no release artifacts found in $RELEASE_DIR" >&2
+        echo "       expected: .tar.gz, .deb, .dmg, .exe, .zip, .AppImage" >&2
+        exit 4
+    fi
+
+    echo "  Found ${#ARTIFACTS[@]} artifact(s):"
+    for a in "${ARTIFACTS[@]}"; do echo "    - $a"; done
+    echo ""
+
+    # Regenerate SHA256SUMS from scratch (deterministic sort).
+    : > SHA256SUMS
+    for a in "${ARTIFACTS[@]}"; do
+        sha256sum "$a" >> SHA256SUMS
+    done
+    echo "✓ Wrote SHA256SUMS"
+
+    # Detached signature over each artifact.
+    for a in "${ARTIFACTS[@]}"; do
+        rm -f "${a}.asc"
+        if gpg --batch --yes \
+               --local-user "$SIGN_KEY" \
+               --armor --detach-sign \
+               --output "${a}.asc" \
+               "$a" 2>/dev/null; then
+            echo "✓ Signed ${a}"
+        else
+            echo "✗ Failed to sign ${a}" >&2
+            exit 5
+        fi
+    done
+
+    # Detached signature over SHA256SUMS (this is what verifiers actually check
+    # first; individual .asc files are belt-and-suspenders).
+    rm -f SHA256SUMS.asc
+    if gpg --batch --yes \
+           --local-user "$SIGN_KEY" \
+           --armor --detach-sign \
+           --output SHA256SUMS.asc \
+           SHA256SUMS 2>/dev/null; then
+        echo "✓ Signed SHA256SUMS"
+    else
+        echo "✗ Failed to sign SHA256SUMS" >&2
+        exit 5
+    fi
+
+    echo ""
+    echo "Done. To verify from this directory:"
+    echo "  gpg --verify SHA256SUMS.asc SHA256SUMS"
+    echo "  sha256sum -c SHA256SUMS"
+    echo ""
+    echo "Or run: $0 --verify $RELEASE_DIR"
+    exit 0
+fi
+
+# ── Verify mode ───────────────────────────────────────────────────────────
+if [ "$MODE" = "verify" ]; then
+    command -v gpg >/dev/null || { echo "ERROR: gpg not found" >&2; exit 3; }
+
+    FAILED=0
+
+    echo "Verifying signatures in $RELEASE_DIR..."
+    echo ""
+
+    # Verify SHA256SUMS.asc if present (this is the master signature).
+    if [ -f SHA256SUMS ] && [ -f SHA256SUMS.asc ]; then
+        if gpg --verify SHA256SUMS.asc SHA256SUMS 2>/dev/null; then
+            echo "✓ SHA256SUMS signature: VALID ($(gpg --list-packets < SHA256SUMS.asc 2>/dev/null | grep -oP 'keyid \K[A-F0-9]+' | head -1 || echo unknown))"
+        else
+            echo "✗ SHA256SUMS signature: INVALID"
+            FAILED=$((FAILED + 1))
+        fi
+    else
+        echo "(no SHA256SUMS / SHA256SUMS.asc; skipping master signature)"
+    fi
+
+    # Verify each artifact's individual signature.
+    while IFS= read -r -d '' asc; do
+        artifact="${asc%.asc}"
+        if [ ! -f "$artifact" ]; then
+            echo "✗ $asc: artifact missing ($artifact)"
+            FAILED=$((FAILED + 1))
+            continue
+        fi
+        if gpg --verify "$asc" "$artifact" 2>/dev/null; then
+            echo "✓ $artifact signature: VALID"
+        else
+            echo "✗ $artifact signature: INVALID"
+            FAILED=$((FAILED + 1))
+        fi
+    done < <(find . -maxdepth 1 -name "*.asc" -not -name "SHA256SUMS.asc" -print0 | sort -z)
+
+    # Verify checksums.
+    if [ -f SHA256SUMS ]; then
+        echo ""
+        echo "Verifying checksums..."
+        if sha256sum -c SHA256SUMS 2>&1 | tail -n +3; then
+            :  # sha256sum -c outputs per-file status; aggregate below
+        fi
+        # Count any "FAILED" lines from sha256sum -c output.
+        CHECKSUM_FAILS="$(sha256sum -c SHA256SUMS 2>&1 | grep -c ': FAILED' || true)"
+        if [ "$CHECKSUM_FAILS" -gt 0 ]; then
+            echo "✗ $CHECKSUM_FAILS checksum(s) FAILED"
+            FAILED=$((FAILED + CHECKSUM_FAILS))
+        else
+            echo "✓ All checksums match SHA256SUMS"
+        fi
+    fi
+
+    echo ""
+    if [ "$FAILED" -eq 0 ]; then
+        echo "✓ ALL VERIFICATIONS PASSED"
+        exit 0
+    else
+        echo "✗ $FAILED VERIFICATION(S) FAILED"
+        exit 1
+    fi
+fi

scripts/verify-reproducible-build.sh

@@ -0,0 +1,130 @@
+#!/usr/bin/env bash
+# verify-reproducible-build.sh
+#
+# Builds the Triangles daemon (trianglesd) twice from the same source tree
+# into two separate build directories, then compares the resulting
+# SHA256 hashes. Exits 0 if the two builds produce byte-identical binaries,
+# non-zero otherwise.
+#
+# Usage:
+#   scripts/verify-reproducible-build.sh                       # default: trianglesd, Release
+#   BUILD_TYPE=Debug  scripts/verify-reproducible-build.sh     # override build type
+#   TARGET=triangles-qt scripts/verify-reproducible-build.sh   # build Qt wallet instead
+#
+# What "reproducible" means here:
+#   Given identical source tree, identical compiler toolchain, identical
+#   build flags, identical SOURCE_DATE_EPOCH (if set) -- the resulting
+#   binary must hash identically across separate build directories.
+#
+# This script does NOT enforce compiler version pinning. Two different
+# GCC versions will legitimately produce different binaries even with
+# identical flags. The verification is "same source + same toolchain =
+# same binary."
+#
+# Pass criteria:
+#   1. Both builds succeed
+#   2. Both binaries exist
+#   3. SHA256 of the two binaries is equal
+#
+# On failure: prints the two SHA256s and the diff in size so a reviewer
+# can investigate. Common causes of non-determinism:
+#   - __DATE__/__TIME__ embedded (we eliminate this in CMakeLists.txt)
+#   - absolute paths in __FILE__ (mitigated by -ffile-prefix-map)
+#   - uninitialized stack/heap contents (should not affect final binary)
+#   - linker adds random base addresses (PIE; deterministic if compiled
+#     with -fno-pie)
+
+set -euo pipefail
+
+# ── Config ─────────────────────────────────────────────────────────────────
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+SOURCE_DIR="${SOURCE_DIR:-$(cd "$SCRIPT_DIR/.." && pwd)}"
+BUILD_TYPE="${BUILD_TYPE:-Release}"
+TARGET="${TARGET:-trianglesd}"
+# Skip Qt by default -- it's slow and adds CI noise. Override with TARGET=triangles-qt
+: "${BUILD_QT:=OFF}"
+BUILD_DIR_A="${BUILD_DIR_A:-/tmp/triangles-repro-A}"
+BUILD_DIR_B="${BUILD_DIR_B:-/tmp/triangles-repro-B}"
+LOG_A="${LOG_A:-/tmp/triangles-repro-A.log}"
+LOG_B="${LOG_B:-/tmp/triangles-repro-B.log}"
+
+# ── Preflight ──────────────────────────────────────────────────────────────
+command -v cmake >/dev/null || { echo "ERROR: cmake not found" >&2; exit 2; }
+command -v ninja >/dev/null || { echo "ERROR: ninja not found (apt install ninja-build)" >&2; exit 2; }
+command -v sha256sum >/dev/null || { echo "ERROR: sha256sum not found" >&2; exit 2; }
+
+if [ ! -d "$SOURCE_DIR" ]; then
+    echo "ERROR: source dir not found: $SOURCE_DIR" >&2
+    exit 2
+fi
+
+# Refuse to run if the working tree is dirty -- dirty tree = non-deterministic
+# git describe output = non-deterministic binary. Run on a clean checkout
+# or a release tag.
+if [ -n "$(cd "$SOURCE_DIR" && git status --porcelain 2>/dev/null)" ]; then
+    echo "WARNING: working tree has uncommitted changes." >&2
+    echo "         build.h will include '-dirty' suffix and the binary will NOT be" >&2
+    echo "         reproducible. Commit/stash your changes first, or accept that the" >&2
+    echo "         hashes below prove your dirty-tree build is at least internally consistent." >&2
+fi
+
+# ── Helpers ────────────────────────────────────────────────────────────────
+build_one() {
+    local dir="$1" log="$2"
+    rm -rf "$dir"
+    mkdir -p "$dir"
+    echo "  configuring in $dir (BUILD_TYPE=$BUILD_TYPE BUILD_QT=$BUILD_QT)..." >&2
+    cmake -S "$SOURCE_DIR" -B "$dir" \
+        -DCMAKE_BUILD_TYPE="$BUILD_TYPE" \
+        -DBUILD_QT="$BUILD_QT" \
+        > "$log" 2>&1 || { echo "  configure failed; see $log" >&2; tail -30 "$log" >&2; exit 3; }
+    echo "  building target $TARGET..." >&2
+    cmake --build "$dir" --target "$TARGET" -j "$(nproc)" \
+        >> "$log" 2>&1 || { echo "  build failed; see $log" >&2; tail -30 "$log" >&2; exit 3; }
+    # ONLY stdout of the find goes to the caller. Progress logs above
+    # were redirected to stderr so they don't pollute the captured path.
+    find "$dir" -name "$TARGET" -type f -executable | head -1
+}
+
+# ── Build twice ────────────────────────────────────────────────────────────
+echo "Building $TARGET ($BUILD_TYPE) twice from $SOURCE_DIR..."
+echo ""
+BIN_A="$(build_one "$BUILD_DIR_A" "$LOG_A")"
+BIN_B="$(build_one "$BUILD_DIR_B" "$LOG_B")"
+
+if [ -z "$BIN_A" ] || [ -z "$BIN_B" ]; then
+    echo "ERROR: could not find built binary" >&2
+    echo "  A: '$BIN_A'" >&2
+    echo "  B: '$BIN_B'" >&2
+    exit 4
+fi
+
+# ── Compare ────────────────────────────────────────────────────────────────
+HASH_A="$(sha256sum "$BIN_A" | awk '{print $1}')"
+HASH_B="$(sha256sum "$BIN_B" | awk '{print $1}')"
+SIZE_A="$(stat -c%s "$BIN_A" 2>/dev/null || stat -f%z "$BIN_A")"
+SIZE_B="$(stat -c%s "$BIN_B" 2>/dev/null || stat -f%z "$BIN_B")"
+
+echo ""
+echo "Binary A: $BIN_A"
+echo "  sha256: $HASH_A"
+echo "  size:   $SIZE_A bytes"
+echo "Binary B: $BIN_B"
+echo "  sha256: $HASH_B"
+echo "  size:   $SIZE_B bytes"
+echo ""
+
+if [ "$HASH_A" = "$HASH_B" ]; then
+    echo "✓ REPRODUCIBLE: both builds produced identical SHA256"
+    exit 0
+else
+    echo "✗ NOT REPRODUCIBLE: hashes differ"
+    echo ""
+    echo "Likely causes:"
+    echo "  - __DATE__/__TIME__ embedded (check src/version.cpp)"
+    echo "  - absolute build paths in __FILE__ (check CMakeLists.txt for -ffile-prefix-map)"
+    echo "  - dirty git tree (commit/stash and rerun)"
+    echo "  - PIE base randomization (compile with -fno-pie -no-pie for testing)"
+    echo "  - non-deterministic linker output (linker version mismatch)"
+    exit 1
+fi