feat: add notnet crate and YubikeySource, thread Tailscale into notstrap

- New crates/notnet: TailscaleOptions, ensure_connected(), auth key chain
  (TS_AUTHKEY env → YubiKey PIV 9d → interactive prompt), install via
  apt/brew/pacman or official install.sh, peer reachability verification
- notsecrets: YubikeySource implementing IdentitySource, reads age key from
  PIV slot 9c; gated behind optional `yubikey` feature
- notstrap: Tailscale step inserted between prerequisites and clone;
  BootstrapOptions.tailscale controls override/skip; NotstrapConfig gains
  optional [tailscale] section; dotfiles_repo is now Option<String> (Tailscale
  gitea_url takes precedence); identity chain adds YubikeySource before
  Bitwarden
- Updated workspace Cargo.toml: notnet added to members and workspace deps
- Integration tests: tailscale: Some(None) to skip Tailscale in all test opts

.superpowers/brainstorm/72758-1776397235/content/architecture.html

@@ -0,0 +1,71 @@
+<h2>notfiles + Tailscale — Bootstrap Architecture</h2>
+<p class="subtitle">How the crates fit together for ephemeral machine setup</p>
+
+<div class="section">
+  <div style="background:#1a1a2e;border-radius:12px;padding:24px;font-family:monospace;font-size:13px;line-height:2;color:#e0e0e0;">
+
+    <div style="display:flex;gap:12px;align-items:flex-start;flex-wrap:wrap;">
+
+      <!-- Fresh machine -->
+      <div style="border:2px solid #4a9eff;border-radius:8px;padding:16px;min-width:160px;background:#0d1b2a;">
+        <div style="color:#4a9eff;font-weight:bold;margin-bottom:8px;">New Machine</div>
+        <div style="color:#aaa;font-size:12px;">TS_AUTHKEY env var</div>
+        <div style="color:#aaa;font-size:12px;">YubiKey (PIV slot 9d)</div>
+        <div style="color:#aaa;font-size:12px;">→ interactive prompt</div>
+      </div>
+
+      <div style="color:#888;font-size:20px;margin-top:28px;">→</div>
+
+      <!-- notstrap -->
+      <div style="border:2px solid #f0c040;border-radius:8px;padding:16px;min-width:160px;background:#1a1500;">
+        <div style="color:#f0c040;font-weight:bold;margin-bottom:8px;">notstrap</div>
+        <div style="color:#aaa;font-size:12px;">1. prereqs check</div>
+        <div style="color:#aaa;font-size:12px;">2. → <span style="color:#ff7eb3">notnet</span></div>
+        <div style="color:#aaa;font-size:12px;">3. clone Gitea</div>
+        <div style="color:#aaa;font-size:12px;">4. → <span style="color:#7effa0">notsecrets</span></div>
+        <div style="color:#aaa;font-size:12px;">5. link dotfiles</div>
+        <div style="color:#aaa;font-size:12px;">6. run hooks</div>
+      </div>
+
+      <div style="display:flex;flex-direction:column;gap:12px;margin-top:0;">
+
+        <div style="display:flex;align-items:center;gap:8px;">
+          <div style="color:#888;font-size:20px;">→</div>
+          <!-- notnet -->
+          <div style="border:2px solid #ff7eb3;border-radius:8px;padding:16px;min-width:160px;background:#1a0a14;">
+            <div style="color:#ff7eb3;font-weight:bold;margin-bottom:8px;">notnet <span style="color:#666;font-size:10px;">NEW</span></div>
+            <div style="color:#aaa;font-size:12px;">detect existing Tailscale</div>
+            <div style="color:#aaa;font-size:12px;">install if missing</div>
+            <div style="color:#aaa;font-size:12px;">resolve auth key</div>
+            <div style="color:#aaa;font-size:12px;">join tailnet</div>
+            <div style="color:#aaa;font-size:12px;">verify peer reachable</div>
+          </div>
+          <div style="color:#888;font-size:20px;">→</div>
+          <div style="border:2px solid #7effa0;border-radius:8px;padding:12px;min-width:120px;background:#001a08;">
+            <div style="color:#7effa0;font-weight:bold;margin-bottom:6px;">Tailnet</div>
+            <div style="color:#aaa;font-size:12px;">minibox (VPS)</div>
+            <div style="color:#aaa;font-size:12px;">Gitea repo</div>
+          </div>
+        </div>
+
+        <div style="display:flex;align-items:center;gap:8px;">
+          <div style="color:#888;font-size:20px;">→</div>
+          <!-- notsecrets -->
+          <div style="border:2px solid #7effa0;border-radius:8px;padding:16px;min-width:160px;background:#001a08;">
+            <div style="color:#7effa0;font-weight:bold;margin-bottom:8px;">notsecrets <span style="color:#666;font-size:10px;">+YubiKey</span></div>
+            <div style="color:#aaa;font-size:12px;">YubikeySource (PIV 9c)</div>
+            <div style="color:#aaa;font-size:12px;">BitwardenSource</div>
+            <div style="color:#aaa;font-size:12px;">FileSource</div>
+            <div style="color:#aaa;font-size:12px;">PromptSource</div>
+          </div>
+        </div>
+
+      </div>
+
+    </div>
+
+    <div style="margin-top:20px;padding-top:16px;border-top:1px solid #333;color:#888;font-size:11px;">
+      Already on Tailnet? notstrap detects active Tailscale → skips notnet entirely
+    </div>
+  </div>
+</div>

.superpowers/brainstorm/72758-1776397235/state/server-info

@@ -0,0 +1 @@
+{"type":"server-started","port":63245,"host":"127.0.0.1","url_host":"localhost","url":"http://localhost:63245","screen_dir":"/Users/joe/dev/notfiles/.superpowers/brainstorm/72758-1776397235/content","state_dir":"/Users/joe/dev/notfiles/.superpowers/brainstorm/72758-1776397235/state"}

.superpowers/brainstorm/72758-1776397235/state/server.log

@@ -0,0 +1,2 @@
+{"type":"server-started","port":63245,"host":"127.0.0.1","url_host":"localhost","url":"http://localhost:63245","screen_dir":"/Users/joe/dev/notfiles/.superpowers/brainstorm/72758-1776397235/content","state_dir":"/Users/joe/dev/notfiles/.superpowers/brainstorm/72758-1776397235/state"}
+{"type":"screen-added","file":"/Users/joe/dev/notfiles/.superpowers/brainstorm/72758-1776397235/content/architecture.html"}

.superpowers/brainstorm/72758-1776397235/state/server.pid

@@ -0,0 +1 @@
+72766

Cargo.lock

@@ -107,6 +107,12 @@ version = "1.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c08606f8c3cbf4ce6ec8e28fb0014a2c086708fe954eaa885384a6165172e7e8"
 
+[[package]]
+name = "base16ct"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4c7f02d4ea65f2c1853089ffd8d2787bdbc63de2f0d29dedbcf8ccdfa0ccd4cf"
+
 [[package]]
 name = "base64"
 version = "0.22.1"
@@ -342,6 +348,18 @@ version = "0.8.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d0a5c400df2834b80a4c3327b3aad3a4c4cd4de0629063962b03235697506a28"
 
+[[package]]
+name = "crypto-bigint"
+version = "0.5.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0dc92fb57ca44df6db8059111ab3af99a63d5d0f8375d9972e319a379c6bab76"
+dependencies = [
+ "generic-array",
+ "rand_core",
+ "subtle",
+ "zeroize",
+]
+
 [[package]]
 name = "crypto-common"
 version = "0.1.7"
@@ -387,10 +405,32 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e7c1832837b905bbfb5101e07cc24c8deddf52f93225eee6ead5f4d63d53ddcb"
 dependencies = [
  "const-oid",
+ "der_derive",
+ "flagset",
  "pem-rfc7468",
  "zeroize",
 ]
 
+[[package]]
+name = "der_derive"
+version = "0.7.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8034092389675178f570469e6c3b0465d3d30b4505c294a6550db47f3c17ad18"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "des"
+version = "0.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ffdd80ce8ce993de27e9f063a444a4d53ce8e8db4c1f00cc03af5ad5a9867a1e"
+dependencies = [
+ "cipher",
+]
+
 [[package]]
 name = "difflib"
 version = "0.4.0"
@@ -436,6 +476,20 @@ version = "0.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "780955b8b195a21ab8e4ac6b60dd1dbdcec1dc6c51c0617964b08c81785e12c9"
 
+[[package]]
+name = "ecdsa"
+version = "0.16.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ee27f32b5c5292967d2d4a9d7f1e0b0aed2c15daded5a60300e4abb9d8020bca"
+dependencies = [
+ "der",
+ "digest",
+ "elliptic-curve",
+ "rfc6979",
+ "signature",
+ "spki",
+]
+
 [[package]]
 name = "ed25519"
 version = "2.2.3"
@@ -466,6 +520,27 @@ version = "1.15.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "48c757948c5ede0e46177b7add2e67155f70e33c07fea8284df6576da70b3719"
 
+[[package]]
+name = "elliptic-curve"
+version = "0.13.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b5e6043086bf7973472e0c7dff2142ea0b680d30e18d9cc40f267efbf222bd47"
+dependencies = [
+ "base16ct",
+ "crypto-bigint",
+ "digest",
+ "ff",
+ "generic-array",
+ "group",
+ "hkdf",
+ "pem-rfc7468",
+ "pkcs8",
+ "rand_core",
+ "sec1",
+ "subtle",
+ "zeroize",
+]
+
 [[package]]
 name = "env_home"
 version = "0.1.0"
@@ -494,6 +569,16 @@ version = "2.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "37909eebbb50d72f9059c3b6d82c0463f2ff062c9e95845c43a6c9c0355411be"
 
+[[package]]
+name = "ff"
+version = "0.13.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c0b50bfb653653f9ca9095b427bed08ab8d75a137839d9ad64eb11810d5b6393"
+dependencies = [
+ "rand_core",
+ "subtle",
+]
+
 [[package]]
 name = "fiat-crypto"
 version = "0.2.9"
@@ -506,6 +591,12 @@ version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5baebc0774151f905a1a2cc41989300b1e6fbb29aff0ceffa1064fdd3088d582"
 
+[[package]]
+name = "flagset"
+version = "0.4.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b7ac824320a75a52197e8f2d787f6a38b6718bb6897a35142d749af3c0e8f4fe"
+
 [[package]]
 name = "foldhash"
 version = "0.1.5"
@@ -520,6 +611,7 @@ checksum = "85649ca51fd72272d7821adaf274ad91c288277713d9c18820d8499a7ff69e9a"
 dependencies = [
  "typenum",
  "version_check",
+ "zeroize",
 ]
 
 [[package]]
@@ -570,6 +662,17 @@ dependencies = [
  "walkdir",
 ]
 
+[[package]]
+name = "group"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f0f9ef7462f7c099f518d754361858f86d8a07af53ba9af0fe635bbccb151a63"
+dependencies = [
+ "ff",
+ "rand_core",
+ "subtle",
+]
+
 [[package]]
 name = "hashbrown"
 version = "0.15.5"
@@ -766,6 +869,22 @@ version = "2.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f8ca58f447f06ed17d5fc4043ce1b10dd205e060fb3ce5b979b8ed8e59ff3f79"
 
+[[package]]
+name = "minimal-lexical"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "68354c5c6bd36d73ff3feceb05efa59b6acb7626617f4962be322a825e61f79a"
+
+[[package]]
+name = "nom"
+version = "7.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d273983c5a657a70a3e8f2a01329822f3b8c8172b73826411a55751e404a0a4a"
+dependencies = [
+ "memchr",
+ "minimal-lexical",
+]
+
 [[package]]
 name = "notcore"
 version = "0.1.0"
@@ -819,6 +938,17 @@ dependencies = [
  "toml",
 ]
 
+[[package]]
+name = "notnet"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+ "rpassword",
+ "serde",
+ "thiserror 2.0.18",
+ "yubikey",
+]
+
 [[package]]
 name = "notsecrets"
 version = "0.1.0"
@@ -841,6 +971,7 @@ dependencies = [
  "tempfile",
  "thiserror 2.0.18",
  "x25519-dalek",
+ "yubikey",
  "zeroize",
 ]
 
@@ -853,6 +984,7 @@ dependencies = [
  "notcore",
  "notfiles",
  "nothooks",
+ "notnet",
  "notsecrets",
  "serde",
  "toml",
@@ -871,6 +1003,7 @@ dependencies = [
  "num-iter",
  "num-traits",
  "rand",
+ "serde",
  "smallvec",
  "zeroize",
 ]
@@ -929,6 +1062,30 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "04744f49eae99ab78e0d5c0b603ab218f515ea8cfe5a456d7629ad883a3b6e7d"
 
+[[package]]
+name = "p256"
+version = "0.13.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c9863ad85fa8f4460f9c48cb909d38a0d689dba1f6f6988a5e3e0d31071bcd4b"
+dependencies = [
+ "ecdsa",
+ "elliptic-curve",
+ "primeorder",
+ "sha2",
+]
+
+[[package]]
+name = "p384"
+version = "0.13.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fe42f1670a52a47d448f14b6a5c61dd78fce51856e68edaa38f7ae3a46b8d6b6"
+dependencies = [
+ "ecdsa",
+ "elliptic-curve",
+ "primeorder",
+ "sha2",
+]
+
 [[package]]
 name = "password-hash"
 version = "0.5.0"
@@ -950,6 +1107,25 @@ dependencies = [
  "hmac",
 ]
 
+[[package]]
+name = "pcsc"
+version = "2.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7dd833ecf8967e65934c49d3521a175929839bf6d0e497f3bd0d3a2ca08943da"
+dependencies = [
+ "bitflags",
+ "pcsc-sys",
+]
+
+[[package]]
+name = "pcsc-sys"
+version = "1.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e14ef017e15d2e5592a9e39a346c1dbaea5120bab7ed7106b210ef58ebd97003"
+dependencies = [
+ "pkg-config",
+]
+
 [[package]]
 name = "pem-rfc7468"
 version = "0.7.0"
@@ -980,6 +1156,12 @@ dependencies = [
  "spki",
 ]
 
+[[package]]
+name = "pkg-config"
+version = "0.3.33"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "19f132c84eca552bf34cab8ec81f1c1dcc229b811638f9d283dceabe58c5569e"
+
 [[package]]
 name = "poly1305"
 version = "0.8.0"
@@ -1037,6 +1219,15 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "primeorder"
+version = "0.13.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "353e1ca18966c16d9deb1c69278edbc5f194139612772bd9537af60ac231e1e6"
+dependencies = [
+ "elliptic-curve",
+]
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.106"
@@ -1119,6 +1310,16 @@ version = "0.8.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dc897dd8d9e8bd1ed8cdad82b5966c3e0ecae09fb1907d58efaa013543185d0a"
 
+[[package]]
+name = "rfc6979"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f8dd2a808d456c4a54e300a23e9f5a67e122c3024119acbfd73e3bf664491cb2"
+dependencies = [
+ "hmac",
+ "subtle",
+]
+
 [[package]]
 name = "rpassword"
 version = "7.4.0"
@@ -1219,6 +1420,29 @@ dependencies = [
  "sha2",
 ]
 
+[[package]]
+name = "sec1"
+version = "0.7.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d3e97a565f76233a6003f9f5c54be1d9c5bdfa3eccfb189469f11ec4901c47dc"
+dependencies = [
+ "base16ct",
+ "der",
+ "generic-array",
+ "pkcs8",
+ "subtle",
+ "zeroize",
+]
+
+[[package]]
+name = "secrecy"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9bd1c54ea06cfd2f6b63219704de0b9b4f72dcc2b8fdef820be6cd799780e91e"
+dependencies = [
+ "zeroize",
+]
+
 [[package]]
 name = "semver"
 version = "1.0.27"
@@ -1281,6 +1505,17 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "sha1"
+version = "0.10.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e3bf829a2d51ab4a5ddf1352d8470c140cadc8301b2ae1789db023f01cedd6ba"
+dependencies = [
+ "cfg-if",
+ "cpufeatures",
+ "digest",
+]
+
 [[package]]
 name = "sha2"
 version = "0.10.9"
@@ -1412,6 +1647,27 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "tls_codec"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0de2e01245e2bb89d6f05801c564fa27624dbd7b1846859876c7dad82e90bf6b"
+dependencies = [
+ "tls_codec_derive",
+ "zeroize",
+]
+
+[[package]]
+name = "tls_codec_derive"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2d2e76690929402faae40aebdda620a2c0e25dd6d3b9afe48867dfd95991f4bd"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "toml"
 version = "0.8.23"
@@ -1487,6 +1743,17 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "06abde3611657adf66d383f00b093d7faecc7fa57071cce2578660c9f1010821"
 
+[[package]]
+name = "uuid"
+version = "1.23.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ddd74a9687298c6858e9b88ec8935ec45d22e8fd5e6394fa1bd4e99a87789c76"
+dependencies = [
+ "getrandom 0.4.2",
+ "js-sys",
+ "wasm-bindgen",
+]
+
 [[package]]
 name = "version_check"
 version = "0.9.5"
@@ -1892,6 +2159,53 @@ dependencies = [
  "zeroize",
 ]
 
+[[package]]
+name = "x509-cert"
+version = "0.2.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1301e935010a701ae5f8655edc0ad17c44bad3ac5ce8c39185f75453b720ae94"
+dependencies = [
+ "const-oid",
+ "der",
+ "sha1",
+ "signature",
+ "spki",
+ "tls_codec",
+]
+
+[[package]]
+name = "yubikey"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7d1efb43c1e3edd4cf871c8dc500d900abfa083c1f2bab10b781ea8ffcadedcb"
+dependencies = [
+ "base16ct",
+ "der",
+ "des",
+ "ecdsa",
+ "elliptic-curve",
+ "hmac",
+ "log",
+ "nom",
+ "num-bigint-dig",
+ "num-integer",
+ "num-traits",
+ "p256",
+ "p384",
+ "pbkdf2",
+ "pcsc",
+ "rand_core",
+ "rsa",
+ "secrecy",
+ "sha1",
+ "sha2",
+ "signature",
+ "subtle",
+ "uuid",
+ "x509-cert",
+ "zeroize",
+]
+
 [[package]]
 name = "zerocopy"
 version = "0.8.48"

Cargo.toml

@@ -7,6 +7,7 @@ members = [
     "crates/notfiles",
     "crates/notsecrets",
     "crates/nothooks",
+    "crates/notnet",
     "crates/notstrap",
     "crates/notgraph",
     "tests/integration",
@@ -30,6 +31,7 @@ notcore     = { path = "crates/notcore" }
 notfiles    = { path = "crates/notfiles" }
 notsecrets  = { path = "crates/notsecrets" }
 nothooks    = { path = "crates/nothooks" }
+notnet      = { path = "crates/notnet" }
 
 [profile.release]
 opt-level = 3

crates/notnet/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name    = "notnet"
+version = "0.1.0"
+edition = "2024"
+license.workspace = true
+description = "Tailscale network presence management for notstrap"
+
+[dependencies]
+anyhow    = { workspace = true }
+thiserror = { workspace = true }
+rpassword = { workspace = true }
+serde     = { workspace = true }
+yubikey   = { version = "0.8", optional = true }
+
+[features]
+default = []
+yubikey = ["dep:yubikey"]

crates/notnet/src/auth.rs

@@ -0,0 +1,49 @@
+/// Auth key resolution chain for Tailscale:
+///
+/// 1. `TS_AUTHKEY` environment variable
+/// 2. YubiKey PIV slot 9d (when compiled with the `yubikey` feature)
+/// 3. Interactive prompt
+///
+/// Returns `Err(NotnetError::NoAuthKey)` if all sources are exhausted without a key.
+use crate::error::NotnetError;
+
+pub fn resolve_auth_key() -> Result<String, NotnetError> {
+    // 1. Environment variable
+    if let Ok(key) = std::env::var("TS_AUTHKEY")
+        && !key.is_empty()
+    {
+        return Ok(key);
+    }
+
+    // 2. YubiKey PIV slot 9d
+    #[cfg(feature = "yubikey")]
+    if let Some(key) = read_yubikey_slot_9d() {
+        return Ok(key);
+    }
+
+    // 3. Interactive prompt
+    prompt_auth_key()
+}
+
+#[cfg(feature = "yubikey")]
+fn read_yubikey_slot_9d() -> Option<String> {
+    use yubikey::{YubiKey, piv};
+
+    let mut yk = YubiKey::open().ok()?;
+    // Slot 9d — key management slot, repurposed here for the Tailscale auth key.
+    let slot = piv::SlotId::KeyManagement; // 0x9d
+    let data = piv::read_object(&mut yk, piv::ObjectId::from(slot)).ok()?;
+    let key = String::from_utf8(data.to_vec()).ok()?;
+    let key = key.trim().to_string();
+    if key.is_empty() { None } else { Some(key) }
+}
+
+fn prompt_auth_key() -> Result<String, NotnetError> {
+    let key = rpassword::prompt_password("Tailscale auth key: ").map_err(NotnetError::Io)?;
+    let key = key.trim().to_string();
+    if key.is_empty() {
+        Err(NotnetError::NoAuthKey)
+    } else {
+        Ok(key)
+    }
+}

crates/notnet/src/error.rs

@@ -0,0 +1,24 @@
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+pub enum NotnetError {
+    #[error("Tailscale is not installed; set install = true in [tailscale] to auto-install")]
+    NotInstalled,
+
+    #[error("Tailscale install failed: {0}")]
+    InstallFailed(String),
+
+    #[error("command `{cmd}` failed: {detail}")]
+    CommandFailed { cmd: String, detail: String },
+
+    #[error("peer `{0}` is unreachable over Tailscale")]
+    PeerUnreachable(String),
+
+    #[error(
+        "auth key resolution failed: no TS_AUTHKEY env var, no YubiKey on slot 9d, and user declined prompt"
+    )]
+    NoAuthKey,
+
+    #[error("I/O error: {0}")]
+    Io(#[from] std::io::Error),
+}

crates/notnet/src/installer.rs

@@ -0,0 +1,92 @@
+use crate::error::NotnetError;
+
+/// Returns true if the `tailscale` binary is on PATH.
+pub fn is_installed() -> bool {
+    std::process::Command::new("tailscale")
+        .arg("version")
+        .output()
+        .map(|o| o.status.success())
+        .unwrap_or(false)
+}
+
+/// Install Tailscale using the platform package manager, falling back to the official
+/// install script.
+///
+/// Supported package managers (tried in order): `apt-get`, `brew`, `pacman`.
+/// Fallback: `curl -fsSL https://tailscale.com/install.sh | sh`.
+pub fn install() -> Result<(), NotnetError> {
+    if try_apt().is_ok() {
+        return Ok(());
+    }
+    if try_brew().is_ok() {
+        return Ok(());
+    }
+    if try_pacman().is_ok() {
+        return Ok(());
+    }
+    install_via_script()
+}
+
+fn try_apt() -> Result<(), NotnetError> {
+    // apt-get install tailscale requires the tailscale repo to be configured already.
+    // We only attempt this if apt-get is present — the user is expected to have added
+    // the Tailscale apt repo as part of their base image or preseed.
+    if !cmd_exists("apt-get") {
+        return Err(not_available("apt-get"));
+    }
+    run_cmd("apt-get", &["install", "-y", "tailscale"])
+}
+
+fn try_brew() -> Result<(), NotnetError> {
+    if !cmd_exists("brew") {
+        return Err(not_available("brew"));
+    }
+    run_cmd("brew", &["install", "tailscale"])
+}
+
+fn try_pacman() -> Result<(), NotnetError> {
+    if !cmd_exists("pacman") {
+        return Err(not_available("pacman"));
+    }
+    run_cmd("pacman", &["-S", "--noconfirm", "tailscale"])
+}
+
+fn install_via_script() -> Result<(), NotnetError> {
+    // Pipe the official install script through sh.
+    // `curl | sh` is the documented method on tailscale.com/download.
+    let output = std::process::Command::new("sh")
+        .args(["-c", "curl -fsSL https://tailscale.com/install.sh | sh"])
+        .output()
+        .map_err(|e| NotnetError::InstallFailed(e.to_string()))?;
+    if !output.status.success() {
+        return Err(NotnetError::InstallFailed(
+            String::from_utf8_lossy(&output.stderr).to_string(),
+        ));
+    }
+    Ok(())
+}
+
+fn cmd_exists(cmd: &str) -> bool {
+    std::process::Command::new("sh")
+        .args(["-c", &format!("command -v {cmd}")])
+        .output()
+        .map(|o| o.status.success())
+        .unwrap_or(false)
+}
+
+fn run_cmd(program: &str, args: &[&str]) -> Result<(), NotnetError> {
+    let output = std::process::Command::new(program)
+        .args(args)
+        .output()
+        .map_err(|e| NotnetError::InstallFailed(e.to_string()))?;
+    if !output.status.success() {
+        return Err(NotnetError::InstallFailed(
+            String::from_utf8_lossy(&output.stderr).to_string(),
+        ));
+    }
+    Ok(())
+}
+
+fn not_available(name: &str) -> NotnetError {
+    NotnetError::InstallFailed(format!("{name} not found"))
+}

crates/notnet/src/lib.rs

@@ -0,0 +1,80 @@
+pub mod auth;
+pub mod error;
+pub mod installer;
+pub mod ports;
+
+pub use error::NotnetError;
+pub use ports::TailscaleOptions;
+
+use anyhow::Result;
+
+/// Ensure this machine is connected to the tailnet and the target peer is reachable.
+///
+/// Returns immediately (skipped) if `tailscale status` reports an active connection.
+/// Installs Tailscale if `opts.install` is true and the binary is missing.
+pub fn ensure_connected(opts: &TailscaleOptions) -> Result<bool, NotnetError> {
+    // Already connected — fast path.
+    if status::is_connected() {
+        return Ok(false); // false = skipped (already on tailnet)
+    }
+
+    // Install if missing and opts.install allows it.
+    if !installer::is_installed() {
+        if !opts.install {
+            return Err(NotnetError::NotInstalled);
+        }
+        installer::install()?;
+    }
+
+    // Resolve auth key.
+    let auth_key = auth::resolve_auth_key()?;
+
+    // Join the tailnet.
+    join(&auth_key)?;
+
+    // Verify target peer is reachable.
+    verify_peer(&opts.peer_hostname)?;
+
+    Ok(true) // true = connected now
+}
+
+fn join(auth_key: &str) -> Result<(), NotnetError> {
+    let output = std::process::Command::new("tailscale")
+        .args(["up", &format!("--authkey={auth_key}")])
+        .output()
+        .map_err(|e| NotnetError::CommandFailed {
+            cmd: "tailscale up".to_string(),
+            detail: e.to_string(),
+        })?;
+    if !output.status.success() {
+        return Err(NotnetError::CommandFailed {
+            cmd: "tailscale up".to_string(),
+            detail: String::from_utf8_lossy(&output.stderr).to_string(),
+        });
+    }
+    Ok(())
+}
+
+fn verify_peer(hostname: &str) -> Result<(), NotnetError> {
+    let output = std::process::Command::new("tailscale")
+        .args(["ping", "--c", "1", hostname])
+        .output()
+        .map_err(|e| NotnetError::CommandFailed {
+            cmd: format!("tailscale ping {hostname}"),
+            detail: e.to_string(),
+        })?;
+    if !output.status.success() {
+        return Err(NotnetError::PeerUnreachable(hostname.to_string()));
+    }
+    Ok(())
+}
+
+mod status {
+    pub fn is_connected() -> bool {
+        std::process::Command::new("tailscale")
+            .args(["status", "--peers=false"])
+            .output()
+            .map(|o| o.status.success())
+            .unwrap_or(false)
+    }
+}

crates/notnet/src/ports.rs

@@ -0,0 +1,13 @@
+use serde::Deserialize;
+
+/// Configuration for Tailscale network setup.
+#[derive(Debug, Clone, Deserialize)]
+pub struct TailscaleOptions {
+    /// Tailscale hostname of the peer to verify after joining (e.g. "minibox").
+    pub peer_hostname: String,
+    /// Gitea clone URL reachable over the tailnet (e.g. "http://minibox:3000/joe/dotfiles.git").
+    pub gitea_url: String,
+    /// If true, install Tailscale automatically when the binary is missing.
+    #[serde(default)]
+    pub install: bool,
+}

crates/notsecrets/Cargo.toml

@@ -23,6 +23,11 @@ hmac             = "0.12"
 rand             = "0.8"
 zeroize          = "1"
 curve25519-dalek = "4"
+yubikey          = { version = "0.8", optional = true }
+
+[features]
+default = []
+yubikey = ["dep:yubikey"]
 
 [dev-dependencies]
 tempfile = { workspace = true }

crates/notsecrets/src/lib.rs

@@ -18,7 +18,7 @@ pub use ports::IdentitySource;
 pub use recipients::{
     Recipient, ScryptRecipient, SshEd25519Recipient, SshRsaRecipient, X25519Recipient,
 };
-pub use sources::{BitwardenSource, FileSource, PromptSource};
+pub use sources::{BitwardenSource, FileSource, PromptSource, YubikeySource};
 
 /// Try each `IdentitySource` in order; collect all identities that load successfully.
 ///

crates/notsecrets/src/sources/mod.rs

@@ -1,8 +1,10 @@
 pub mod bitwarden;
 pub mod file;
 pub mod prompt;
+pub mod yubikey;
 
 pub use crate::ports::IdentitySource;
 pub use bitwarden::BitwardenSource;
 pub use file::FileSource;
 pub use prompt::PromptSource;
+pub use yubikey::YubikeySource;

crates/notsecrets/src/sources/yubikey.rs

@@ -0,0 +1,72 @@
+use crate::error::AgeError;
+use crate::identities::Identity;
+use crate::ports::IdentitySource;
+
+/// Reads an age private key from YubiKey PIV slot 9c (Digital Signature slot).
+///
+/// Requires the `yubikey` feature to be enabled. When the feature is absent this
+/// source is compiled out entirely — the struct still exists for type-level use but
+/// `load()` always returns an error.
+pub struct YubikeySource;
+
+impl IdentitySource for YubikeySource {
+    fn name(&self) -> &str {
+        "yubikey-piv-9c"
+    }
+
+    fn load(&self) -> Result<Box<dyn Identity>, AgeError> {
+        load_impl()
+    }
+}
+
+#[cfg(feature = "yubikey")]
+fn load_impl() -> Result<Box<dyn Identity>, AgeError> {
+    use crate::identities::x25519::X25519Identity;
+    use yubikey::{YubiKey, piv};
+
+    let mut yk = YubiKey::open().map_err(|e| AgeError::SourceError {
+        name: "yubikey-piv-9c".to_string(),
+        source: anyhow::anyhow!("cannot open YubiKey: {e}"),
+    })?;
+
+    // Slot 9c — Digital Signature slot, used here to store the age private key.
+    let data =
+        piv::read_object(&mut yk, piv::ObjectId::from(piv::SlotId::Signature)).map_err(|e| {
+            AgeError::SourceError {
+                name: "yubikey-piv-9c".to_string(),
+                source: anyhow::anyhow!("cannot read PIV slot 9c: {e}"),
+            }
+        })?;
+
+    let key = std::str::from_utf8(&data)
+        .map_err(|e| AgeError::SourceError {
+            name: "yubikey-piv-9c".to_string(),
+            source: anyhow::anyhow!("PIV slot 9c data is not valid UTF-8: {e}"),
+        })?
+        .trim()
+        .to_string();
+
+    if key.is_empty() {
+        return Err(AgeError::SourceError {
+            name: "yubikey-piv-9c".to_string(),
+            source: anyhow::anyhow!("PIV slot 9c is empty"),
+        });
+    }
+
+    let identity = X25519Identity::from_bech32(&key).map_err(|e| AgeError::SourceError {
+        name: "yubikey-piv-9c".to_string(),
+        source: anyhow::anyhow!("slot 9c content is not a valid AGE-SECRET-KEY-1: {e}"),
+    })?;
+    Ok(Box::new(identity))
+}
+
+#[cfg(not(feature = "yubikey"))]
+fn load_impl() -> Result<Box<dyn Identity>, AgeError> {
+    Err(AgeError::SourceError {
+        name: "yubikey-piv-9c".to_string(),
+        source: anyhow::anyhow!(
+            "notsecrets was compiled without the `yubikey` feature; \
+             YubikeySource is unavailable"
+        ),
+    })
+}

crates/notstrap/Cargo.toml

@@ -18,6 +18,7 @@ notcore     = { workspace = true }
 notfiles    = { workspace = true }
 notsecrets  = { workspace = true }
 nothooks    = { workspace = true }
+notnet      = { workspace = true }
 clap        = { workspace = true }
 anyhow      = { workspace = true }
 which       = { workspace = true }

crates/notstrap/src/lib.rs

@@ -4,25 +4,31 @@ use notfiles::{LinkOptions, link};
 use nothooks::{HookRunner, run_phase};
 use notsecrets::identities::Identity;
 use notsecrets::sources::IdentitySource;
-use notsecrets::{BitwardenSource, FileSource, PromptSource, resolve_identities};
+use notsecrets::{BitwardenSource, FileSource, PromptSource, YubikeySource, resolve_identities};
 use serde::Deserialize;
 use std::path::{Path, PathBuf};
 
 pub mod prereqs;
 pub mod repo;
 
+pub use notnet::TailscaleOptions;
+
 type EnvInjector = Box<dyn Fn(&Path, Vec<Box<dyn Identity>>) -> Result<String>>;
 
 #[derive(Deserialize)]
 pub struct NotstrapConfig {
     pub bootstrap: BootstrapSection,
+    /// When present, notstrap joins the tailnet before cloning dotfiles.
+    pub tailscale: Option<TailscaleOptions>,
     #[serde(default)]
     pub hooks: Vec<notcore::HookSpec>,
 }
 
 #[derive(Deserialize)]
 pub struct BootstrapSection {
-    pub dotfiles_repo: String,
+    /// Required when `[tailscale]` is absent. When `[tailscale]` is present,
+    /// `gitea_url` from that section is used as the clone URL instead.
+    pub dotfiles_repo: Option<String>,
     pub dotfiles_dir: String,
     #[serde(default = "default_bw_item")]
     pub bw_age_item: String,
@@ -42,6 +48,12 @@ pub struct BootstrapOptions {
     pub force: bool,
     pub key_file: Option<PathBuf>,
     pub dotfiles: Option<PathBuf>,
+    /// Override the Tailscale options from the config file. `None` here defers to the
+    /// config; use `Some(None)` to explicitly skip Tailscale even when the config has
+    /// a `[tailscale]` section (useful in tests and CI).
+    ///
+    /// Encoding: `None` = use config, `Some(None)` = skip, `Some(Some(opts))` = override.
+    pub tailscale: Option<Option<TailscaleOptions>>,
     /// None = skip prereq check (tests). Some(f) = run f().
     pub check_prereqs: Option<Box<dyn Fn() -> Result<()>>>,
     /// None = skip env injection (tests). Some(f) = decrypt sops at path and inject.
@@ -76,8 +88,37 @@ pub fn run(opts: BootstrapOptions) -> Result<Report> {
         })?,
     };
 
-    // 3. Clone dotfiles if missing
+    // Resolve which Tailscale options to use: CLI override > config > None.
-    match repo::clone_if_missing(&cfg.bootstrap.dotfiles_repo, &dotfiles_dir) {
+    let ts_opts: Option<TailscaleOptions> = match opts.tailscale {
+        Some(override_val) => override_val, // Some(None) = skip, Some(Some(o)) = use override
+        None => cfg.tailscale.clone(),      // defer to config
+    };
+
+    // Resolve dotfiles clone URL: Tailscale gitea_url takes precedence over dotfiles_repo.
+    let clone_url: Option<String> = ts_opts
+        .as_ref()
+        .map(|ts| ts.gitea_url.clone())
+        .or_else(|| cfg.bootstrap.dotfiles_repo.clone());
+
+    // 3. Tailscale (inserted before clone, skipped when ts_opts is None)
+    if let Some(ref ts) = ts_opts {
+        match notnet::ensure_connected(ts) {
+            Ok(true) => report.add("tailscale", StepStatus::Ok),
+            Ok(false) => report.add("tailscale", StepStatus::Skipped),
+            Err(e) => {
+                report.add("tailscale", StepStatus::Failed(e.to_string()));
+                return Ok(report);
+            }
+        }
+    }
+
+    // 4. Clone dotfiles if missing
+    let clone_url = clone_url.ok_or_else(|| {
+        anyhow::anyhow!(
+            "no dotfiles clone URL: set [bootstrap].dotfiles_repo or add a [tailscale] section"
+        )
+    })?;
+    match repo::clone_if_missing(&clone_url, &dotfiles_dir) {
         Ok(true) => {
             report.add("clone dotfiles", StepStatus::Ok);
         }
@@ -90,11 +131,12 @@ pub fn run(opts: BootstrapOptions) -> Result<Report> {
         }
     }
 
-    // 4. Resolve age identities
+    // 5. Resolve age identities
     let sources: Vec<Box<dyn IdentitySource>> = if let Some(kf) = opts.key_file {
         vec![Box::new(FileSource::new(kf))]
     } else {
         vec![
+            Box::new(YubikeySource),
             Box::new(BitwardenSource::new(&cfg.bootstrap.bw_age_item)),
             Box::new(PromptSource),
         ]

crates/notstrap/src/main.rs

@@ -44,6 +44,7 @@ fn main() -> Result<()> {
         force,
         key_file,
         dotfiles,
+        tailscale: None, // defer to [tailscale] section in config (if present)
         check_prereqs: Some(Box::new(prereqs::check_prerequisites)),
         env_injector: None,
     };

tests/integration/tests/bootstrap.rs

@@ -69,6 +69,7 @@ fn make_opts(env: &TestEnv, force: bool) -> BootstrapOptions {
         force,
         key_file: Some(env.key_file.clone()),
         dotfiles: Some(env.dotfiles.path().to_path_buf()),
+        tailscale: Some(None), // skip Tailscale in tests
         check_prereqs: None,
         env_injector: None,
     }
@@ -216,6 +217,7 @@ fn test_bootstrap_fails_fast_on_bad_key() {
         force: false,
         key_file: Some(PathBuf::from("/nonexistent/no-such-key.age")),
         dotfiles: Some(d.to_path_buf()),
+        tailscale: Some(None), // skip Tailscale in tests
         check_prereqs: None,
         env_injector: None,
     };