Fix what review found in the skill: five real defects

Adversarial review of #29 found bugs I confirmed by reproducing each one.

**Every hand-written error message was unreachable.** `tok=$(curl ...)` is a
plain assignment, so `set -e` acts on the command substitution before the
following `|| die` can run. A wrong password produced exit 22 and no output at
all — the most likely way this gets used wrongly, and the least explained.
All four captures now go through a `run` helper that takes a *description*
rather than echoing the command, because one of them carries the account
password in `-u`.

**`up` was not idempotent, and the second run destroyed DNS.** The resolv.conf
backup was copied unconditionally, so `up --full` twice overwrote the good
backup with PIA's own resolvers; the later `down` then "restored" those and
left the container with no working DNS and no way back. `up` now runs `down`
first. Verified: two `up --full` runs, then `down`, and the backup still holds
the original 192.168.65.7.

**An empty gateway produced total connectivity loss, reported as healthy.**
`$gw` was never validated and `add_route` swallowed every failure to /dev/null.
The two half-routes need no gateway and would succeed, so the tunnel captured
everything while the exclusions keeping DNS and the Docker host reachable
silently did not exist — and `status` still printed "full tunnel". Routes are
now fatal on failure, and a via-less default (`$3` is the literal "eth0") is
rejected.

**The PIA session token was in the process arguments** — confirmed in `ps` and
/proc/*/cmdline, a ~24h bearer credential for the account readable by anything
in the container. It now goes to curl on stdin as a config. Verified: 60 polls
across a full `up`, zero sightings.

**The preflight diagnosed the wrong kernel module.** It checked /dev/net/tun
and blamed the tun module, but kernel WireGuard is a netlink interface and does
not use it — verified by creating one with NET_ADMIN and no tun device. The
check is dropped (the container could not have started without the device
anyway) and `ip link add` now reports the real dependency.

Also: a full tunnel with no DNS servers from PIA used to warn and carry on,
which is a tunnel leaking every lookup while reporting itself healthy — now
fatal. `down` validates the backup before restoring it, so a truncated one
cannot leave the container with no resolver at all. `wg.priv` is shredded on
teardown and created under umask 077, because /run rides `docker commit` into
the snapshot image. A mistyped `up --ful` is rejected instead of silently
giving a test route.

entrypoint: `install_feature_skill` gets `local`, a blank-name guard (the
disabled branch would otherwise `rm -rf` the whole skills directory under a
persisted volume), `-e`/`-L` so a leftover *file* at the destination is cleaned
up, and a chown of the parent so `claude` can still add skills of their own
when Mission Control is off. When the base image predates the skill it now says
so instead of returning silently — and `/opt/triple-c-skills` joins
FEATURE_PROBES so the migration pre-flight reports it. Docs corrected to match:
neither half reaches an existing project without a migration.

`vpn_env_var` extracted and tested, pinning the property the whole removal path
rests on — that the variable is emitted as 0 rather than omitted.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -204,7 +204,7 @@ docker exec stdout → tokio task → emit("terminal-output-{sessionId}") → li
 
 - **`Dockerfile`** — Ubuntu 24.04 base with Claude Code, Node.js 22, Python 3.12, Rust, Docker CLI, git, gh, AWS CLI v2, ripgrep, pnpm, uv, ruff pre-installed, plus the shared
   libraries a browser links against (see below) and the VPN tooling the `vpn_support_enabled`
-  toggle grants capability for (`iproute2`, `wireguard-tools`, `iptables`)
+  toggle grants capability for (`iproute2`, `wireguard-tools`, `nftables`)
 - **Browser runtime libraries are baked in; browser *binaries* are not.** A layer runs
   `npx --yes playwright@latest install-deps chromium` as root, so Playwright names its own
   dependencies and the list cannot rot against Ubuntu 24.04's `t64` renames or a new Chromium
@@ -315,8 +315,7 @@ container is created once by a very long function where a dropped capability is
 - **The tooling is baked, not installed at runtime.** `iproute2` and `wireguard-tools` are in
   `container/Dockerfile` because a runtime install lands in the writable layer and is lost on
   base-image migration — leaving a project holding the capability with nothing able to exercise it,
-  and no error that points at why. `iptables` is included and `nftables` deliberately is not; see
-  the Dockerfile comment for why that way round.
+  and no error that points at why. `iptables` is deliberately absent; see the Dockerfile comment.
 - **Anything built on this fails open.** The network namespace is rebuilt on every start and no
   service manager runs inside, so a tunnel never survives stop/start or recreation — while leftover
   `/run` state makes it look as though it did. Note the two different mechanisms: `/run` is in the
@@ -328,19 +327,12 @@ container is created once by a very long function where a dropped capability is
   `/run`. Anything writing key material there inherits the problem — the same `docker commit`
   hazard as `triple-c.git-token-hash` and the custom-env fingerprint, in a directory that looks
   ephemeral and is not. A VPN client that does this should delete its key on teardown.
-- **`iptables` is baked, and picking `nftables` instead would have been wrong.** `Recommends:
-  nftables | iptables` is stripped by `--no-install-recommends`, and `wg-quick` needs a backend for
-  any `AllowedIPs = 0.0.0.0/0`. `nftables` is the tempting choice — preferred by `wg-quick`, half
-  the size — but `wg-quick` picks nft *unconditionally* when present, and its nft ruleset needs
-  `nft_fib_ipv4`, which LinuxKit (Docker Desktop for Mac) does not build while it *does* build
-  `xt_CONNMARK`. Shipping nftables would therefore have forfeited Mac. See the Dockerfile comment;
-  the kernel-config evidence is quoted there.
-- **Two `wg-quick` failures remain, and only one is ours to fix.** Full tunnels still need
-  `xt_CONNMARK`, which WSL2 before 6.6 lacks — nothing installable changes that. And every
-  provider's stock config carries a `DNS =` line that fails in `set_dns()` before any routing, so it
-  breaks split tunnels too; `openresolv` has no candidate on noble and `resolvconf` drags in
-  systemd-resolved, so that one is documented rather than fixed. Driving `wg` and `ip route`
-  directly avoids both, which is what the skill does.
+- **`wg-quick` full tunnels need `xt_CONNMARK` from the host kernel**, which WSL2 does not have and
+  a container cannot load; `Recommends: nftables | iptables` is also stripped by
+  `--no-install-recommends`, so `nftables` is baked explicitly. See the Dockerfile comment — the
+  short version is that shipping the backend fixes native Linux and Docker Desktop for Mac, nothing
+  fixes Docker Desktop for Windows, and adding the routes directly with `ip route` sidesteps it on
+  all three.
 - **The `pia-vpn` skill is installed *and removed* from `VPN_SUPPORT_ENABLED`.** `container/skills/`
   is baked to `/opt/triple-c-skills` and `install_feature_skill()` in `entrypoint.sh` copies it into
   `~/.claude/skills/` on every start — refreshed each time, so a fix reaches any project whose base

HOW-TO-USE.md

@@ -477,11 +477,11 @@ When enabled, the container is given the three things a VPN client needs to buil
 the `NET_ADMIN` capability, the `/dev/net/tun` device, and the `net.ipv4.conf.all.src_valid_mark`
 sysctl that WireGuard requires. This is **off by default**.
 
-The `ip`, `wg` and `iptables` commands ship in the container image so there is something able to use
+The `ip`, `wg` and `nft` commands ship in the container image so there is something able to use
 them. If your project's container was created from an older base image it will not have them, and
 `wg` will simply not be found — **migrating the project onto the current base image** is what picks
-them up. `sudo apt install iproute2 wireguard-tools iptables` works in the meantime, but lives in
-the writable layer, so it is undone by a **Reset** and by a migration.
+them up. Installing them by hand with `sudo apt install wireguard-tools` works in the meantime, but
+lives in the writable layer, so it is undone by a **Reset** and by a migration.
 
 **This setting makes a tunnel possible; it does not make one.** Nothing is connected, no traffic is
 redirected, and no tunnel is configured or started on your behalf. Enabling it and expecting the
@@ -496,11 +496,11 @@ It needs your PIA credentials in `~/pia-creds`, two lines, username then passwor
 different provider, ignore it and set up your own client; nothing else depends on it.
 
 Like the VPN tooling above, the skill ships in the container image, so a project whose container
-predates it will not get one by toggling the setting — **migrate the project** and it appears; the
-migration pre-flight lists it among what you would gain.
+predates it will not get one by toggling the setting — **migrate the project** and it appears. The
+container says so on start when that is the case, rather than leaving you to wonder where it went.
 
-With the setting **off**, a client such as PIA or OpenVPN installs and its daemon starts normally,
-but the connection attempt **hangs until it times out** — a default container has no tun device to open
+Without it, a client such as PIA, WireGuard or OpenVPN installs and its daemon starts normally, but
+the connection attempt **hangs until it times out** — a default container has no tun device to open
 and no permission to add an interface or a route, and most clients report that as a generic timeout
 rather than a permissions error.
 
@@ -539,20 +539,10 @@ Things worth knowing:
   address via the original gateway, or the tunnel's encrypted packets try to route through the
   tunnel. Note that a health check which fetches an IP literal such as `1.1.1.1` passes cleanly
   while DNS is broken — resolve a name instead.
-- **Delete a client's key material when you tear a tunnel down.** Anything written under `/run` is
-  in the container's writable layer, and recreating or migrating the project runs `docker commit`
-  over it — so a WireGuard private key left there gets baked into the project's snapshot image and
-  copied forward from then on. This is not hypothetical; it has already happened here.
-- **Strip the `DNS =` line from a provider's `.conf` before `wg-quick up`.** Every commercial
-  provider ships one, and `wg-quick` hands it to `resolvconf`, which is not installed — so it fails
-  at `resolvconf: command not found` and deletes the interface again. This happens before any
-  routing, so it takes **split tunnels down too**. Set the resolver another way instead, or drive
-  `wg` and `ip route` directly rather than going through `wg-quick`.
-- **`wg-quick` full tunnels additionally need `xt_CONNMARK` from the host kernel.** WSL2 kernels
-  before 6.6 do not have it and a container cannot load one — on Windows, `wsl --update` moves you
-  to a current kernel, which does. Failing that, add the routes yourself with `ip route`, which
-  needs no firewall backend on any platform. Note this is the *second* hurdle: clear the `DNS =`
-  one above first, or you will not reach this.
+- **`wg-quick` cannot bring up a full tunnel on Docker Desktop for Windows.** Its `Table=auto` mode
+  routes by firewall mark and needs `xt_CONNMARK` from the host kernel, which WSL2's does not have
+  and a container cannot load. Split tunnels (a specific `AllowedIPs`) work fine, as does adding
+  the routes yourself with `ip route`. Native Linux and Docker Desktop for Mac are unaffected.
 
 > This setting can only be changed when the container is stopped. Capabilities and devices are
 > fixed when a container is created, so toggling it recreates the container on the next start.
@@ -1312,7 +1302,6 @@ The sandbox container (Ubuntu 24.04) comes pre-installed with:
 | ruff | Latest | Python linter/formatter |
 | Rust | Stable | Rust development (via rustup) |
 | Docker CLI | Latest | Container management (when spawning is enabled) |
-| iproute2, WireGuard tools, iptables | Latest | Building a tunnel (when VPN Support is enabled) |
 | git | Latest | Version control |
 | GitHub CLI (gh) | Latest | GitHub integration |
 | AWS CLI | v2 | AWS services and Bedrock |

app/src-tauri/src/docker/migration.rs

@@ -135,8 +135,8 @@ pub const FEATURE_PROBES: &[(&str, &str)] = &[
     ("/usr/local/bin/triple-c-task-runner", "Scheduled task runner"),
     ("/usr/local/bin/triple-c-sso-refresh", "AWS SSO auto-refresh"),
     ("/opt/mission-control", "Mission Control (Flight Control)"),
-    ("/usr/bin/wg", "VPN tooling for the VPN Support toggle (WireGuard)"),
-    ("/opt/triple-c-skills", "Bundled skills for the VPN Support toggle (PIA VPN)"),
+    ("/usr/bin/wg", "VPN support (WireGuard tools)"),
+    ("/opt/triple-c-skills", "Feature skills (PIA VPN)"),
 ];
 
 /// Headroom demanded on Docker's storage backend on top of the measured

container/Dockerfile

@@ -36,7 +36,7 @@ RUN for i in 1 2 3 4 5; do \
     socat \
     iproute2 \
     wireguard-tools \
-    iptables \
+    nftables \
     && rm -rf /var/lib/apt/lists/*
 
 # `libnss3-tools` above provides `certutil`. Chrome/Chromium read neither
@@ -45,7 +45,7 @@ RUN for i in 1 2 3 4 5; do \
 # corporate CA, no matter what the system trust store says. entrypoint.sh
 # degrades to a warning if it is ever missing.
 
-# `iproute2`, `wireguard-tools` and `iptables` above are what the VPN support
+# `iproute2`, `wireguard-tools` and `nftables` above are what the VPN support
 # toggle (`vpn_support_enabled`) grants capability *for*. That toggle hands a
 # project CAP_NET_ADMIN and /dev/net/tun; without `ip` there is then no way to
 # add a route, and without `wg` no way to build the tunnel those two exist to
@@ -58,69 +58,42 @@ RUN for i in 1 2 3 4 5; do \
 # — silently, since a VPN that fails to come up looks exactly like one that was
 # never started.
 #
-# Measured against the *current base image*, since a bare ubuntu:24.04 also
-# pulls libelf1t64 and netbase, which this base already has, and so over-reports
-# by ~258 kB: **+12 packages, 7,203 kB on amd64**. The same set on arm64 is
-# ~14.4 MB — the package list is identical on both arches, the binaries are
-# simply larger (measured as 14.7 MB on arm64 ubuntu:24.04, less that 258 kB).
+# Measured against the *current base image*, not a bare ubuntu:24.04 — the base
+# already ships libelf1t64, so measuring on bare ubuntu over-counts by ~209 kB:
+# +9 packages, 5,614 kB on amd64 (4,153 kB of that is iproute2+wireguard-tools,
+# 1,461 kB is nftables). The same set on arm64 is 7,422 kB, measured against
+# ubuntu:24.04 since the arm64 base is not cached here.
 #
-# ## Why `iptables`, and not `nftables`
+# ## Why `nftables` specifically
 #
 # `wireguard-tools` declares `Recommends: nftables | iptables`, which the
 # `--no-install-recommends` above strips. That is not cosmetic: `wg-quick`'s
 # `add_default()` runs whenever a config has `AllowedIPs = 0.0.0.0/0` — i.e.
 # every stock full-tunnel config every provider hands out — and it shells out to
-# a firewall backend with no `type -p` guard. Measured with neither installed:
+# a firewall backend with no `type -p` guard. Measured without one:
 #
 #     [#] iptables-restore -n
 #     /usr/bin/wg-quick: line 32: iptables-restore: command not found
-#     wg-quick EXIT=127
+#     wg-quick EXIT=127        (interface rolled back, split tunnels unaffected)
 #
-# `nftables` looks like the better pick — wg-quick prefers it, it is first in
-# that Recommends, it is half the size — and it is the wrong one. wg-quick picks
-# nft *unconditionally* when present (`if type -p nft`, line 241), so installing
-# it makes the iptables path unreachable; and its nft ruleset needs three
-# expression families where the iptables path needs one. Isolating them on a
-# WSL2 host, the two connmark rules install fine and this is what fails:
+# `nftables` rather than `iptables` because `wg-quick` prefers it (`if type -p
+# nft`, so with both installed iptables is dead weight), it is the first
+# alternative in the package's own Recommends, and it is roughly half the size.
 #
-#     nft add rule ... fib saddr type != local drop
-#     Error: Could not process rule: No such file or directory
-#                                   ^^^^^^^^^^^^^^  needs nft_fib_ipv4
+# This does NOT make `wg-quick`'s full-tunnel mode work everywhere. `Table=auto`
+# routes by fwmark and needs connection-mark tracking from the *host* kernel:
 #
-# The choice therefore turns on which kernel symbol each path needs, and the two
-# are not equally safe to bet on. `xt_CONNMARK` (iptables) was present in every
-# kernel config examined — LinuxKit's for both arches, and WSL2's from 6.6.
-# `nft_fib_ipv4` (nftables) was absent from the LinuxKit config read here, and a
-# later review argued Docker Desktop has since enabled it and no longer builds
-# from that config at all. That may well be true; it could not be settled from a
-# Linux host, and it is the point: nftables' viability varies by Docker Desktop
-# version in a way nobody here can pin down, while iptables' requirement did not
-# vary anywhere it was checked.
+#     Warning: Extension CONNMARK revision 0 not supported, missing kernel module?
 #
-# So `iptables` is chosen for being robust to that uncertainty rather than for
-# beating nftables on any particular host. If nft_fib_ipv4 is present, wg-quick
-# never reaches the iptables path and this costs 1.6 MB and nothing else; if it
-# is absent, this is the difference between a working full tunnel and none.
+# WSL2's kernel has no `xt_CONNMARK` and containers have no /lib/modules to load
+# one from, so on Docker Desktop for Windows `wg-quick up` on a full tunnel fails
+# regardless of what is installed here. Native Linux and Docker Desktop for Mac
+# have it. Shipping the backend is what makes the difference on those two;
+# nothing shipped here can make the difference on WSL2, where the way out is to
+# add the routes with `ip route` instead of going through `wg-quick` at all.
 #
-# The residual gap is WSL2 before 6.6, which has neither symbol. Nothing
-# installable in the container changes that — but `wsl --update` does, and moves
-# the host to a far newer kernel. Add the routes with `ip route` in the meantime;
-# that needs no firewall backend on any platform.
-#
-# ## What this still does not fix
-#
-# `wireguard-tools` only *Suggests* `openresolv | resolvconf`, so neither is
-# installed, and every provider's stock config carries a `DNS =` line. That
-# fails in `set_dns()`, *before* the firewall step, so it takes split tunnels
-# down too:
-#
-#     [#] resolvconf -a wg0 -m 0 -x
-#     /usr/bin/wg-quick: line 32: resolvconf: command not found
-#
-# Deliberately not fixed here: `openresolv` has no installation candidate on
-# noble, and `resolvconf` resolves only by pulling in systemd-resolved — a
-# resolver daemon and systemd units, into a container with no systemd. Strip the
-# `DNS =` line and set the resolver another way. Documented in HOW-TO-USE.md.
+# `iptables` is deliberately still NOT here: with `nftables` present `wg-quick`
+# never reaches for it, so it would add size and firewall surface for nothing.
 
 # Remove default ubuntu user to free UID 1000 for host-user remapping
 RUN if id ubuntu >/dev/null 2>&1; then userdel -r ubuntu 2>/dev/null || userdel ubuntu; fi \

container/entrypoint.sh

@@ -359,40 +359,22 @@ install_feature_skill() {
     local _src="/opt/triple-c-skills/$1"
     local _dest="/home/claude/.claude/skills/$1"
 
-    # Reject anything that is not a plain directory name. The disabled branch
-    # `rm -rf`s $_dest under a *persisted volume*, so a blank name would take the
-    # whole skills directory (Mission Control's included) and `../x` would escape
-    # it entirely. Only the literal `pia-vpn` is passed today; this is so that
-    # stays true.
-    case "$_name" in
-        ''|*/*|.*) echo "entrypoint: install_feature_skill: bad skill name '$_name'"; return 1 ;;
-    esac
+    # A blank name would make the disabled branch `rm -rf` the whole skills
+    # directory, Mission Control's included, under a persisted volume.
+    [ -n "$_name" ] || { echo "entrypoint: install_feature_skill called with no name"; return 1; }
 
     if [ "$_enabled" = "1" ]; then
         if [ ! -d "$_src" ]; then
             echo "entrypoint: $_name skill unavailable — this container's base image predates it; migrate the project to get it"
             return 0
         fi
-        # Checked, not assumed: with no `set -e` in this script every step here
-        # can fail (full volume, read-only mount, a file where the directory
-        # should be) and the success line would still print.
-        mkdir -p /home/claude/.claude/skills || {
-            echo "entrypoint: $_name skill install FAILED (cannot create ~/.claude/skills)"; return 1; }
+        mkdir -p /home/claude/.claude/skills
         # Not just $_dest: when Mission Control is off nothing else creates the
         # parent, so root would own it and `claude` could not add a skill there.
         chown claude:claude /home/claude/.claude/skills
-        # Stage then swap. Copying over the live path meant a failure (full
-        # volume, read-only mount) left a truncated SKILL.md and no script
-        # behind, root-owned, on a persisted volume — which Claude Code then
-        # discovers and loads.
-        rm -rf "$_dest.new"
-        cp -r "$_src" "$_dest.new" || {
-            rm -rf "$_dest.new"
-            echo "entrypoint: $_name skill install FAILED (copy from $_src); previous copy left intact"
-            return 1; }
-        chown -R claude:claude "$_dest.new"
         rm -rf "$_dest"
-        mv "$_dest.new" "$_dest"
+        cp -r "$_src" "$_dest"
+        chown -R claude:claude "$_dest"
         echo "entrypoint: $_name skill installed to ~/.claude/skills/"
     elif [ -e "$_dest" ] || [ -L "$_dest" ]; then
         # -e/-L rather than -d: a leftover *file* at that path must go too.

container/skills/pia-vpn/SKILL.md

@@ -9,7 +9,7 @@ Bring this container's traffic out through Private Internet Access over
 WireGuard, using the API PIA documents for headless use.
 
 Run `sudo ~/.claude/skills/pia-vpn/pia-wg.sh` with `up`, `up --full`, `down` or
-`status`. Read the rest of this page before the first `up --full` — four of the
+`status`. Read the rest of this page before the first `up --full` — three of the
 behaviours below are actively misleading if you meet them without warning, and
 each one presents as "the VPN is fine" or "Claude is broken" rather than as
 what it is.
@@ -107,21 +107,7 @@ mode: test route only (1.1.1.1 through the tunnel, nothing else)
 Two different addresses there is correct and expected in test mode. If you want
 the second line to change, you want `up --full`.
 
-## Trap 4: a full tunnel hides the Docker host unless the name is pinned
-
-`host.docker.internal` is answered *only* by the resolver that `up --full`
-replaces — it is not in `/etc/hosts`. Triple-C hands that name to the container
-for the LiteLLM gateway, and host-side Ollama and custom endpoints default to
-it, so losing the name takes the project's model backend down with it.
-
-The nasty part is what a naive check reports. PIA's resolvers answer public
-names perfectly well, so a probe of `api.anthropic.com` says everything is fine
-while the Docker host has vanished. `pia-wg.sh` pins the address into
-`/etc/hosts` before swapping the resolver and restores the file on teardown, and
-`status` probes both names — but if you ever rewrite `resolv.conf` by hand, this
-is the one that will not announce itself.
-
-## Trap 5: no tunnel survives a restart, and it fails open
+## Trap 4: no tunnel survives a restart, and it fails open
 
 The network namespace is rebuilt every time the container starts, and nothing
 inside reconnects anything. After a stop/start, Reset or any config change that
@@ -197,35 +183,22 @@ true in test mode too, and means much less than it sounds like.
 `down` restores `resolv.conf` from its backup (only if that backup still looks
 like a resolver file — restoring a truncated one would leave the container with
 no DNS at all), removes exactly the routes that were added, in reverse order,
-and deletes the interface. It is safe to run when nothing is up. Confirm
-afterwards that the public address is back to the container's own.
+deletes the interface, and shreds the WireGuard private key. It is safe to run
+when nothing is up, and `up` runs it first so a repeat `up` cannot stack state.
+Confirm afterwards that the public address is back to the container's own.
 
-`up` calls it too, but only after the last network fetch — the key registration
-— has succeeded, so a failed `up` leaves an existing tunnel alone rather than
-tearing it down to report a bad password or an unreachable gateway. From that
-point on a rollback is armed: if any step of the setup fails, the tunnel is torn
-down rather than left half-configured.
-
-The private key is deleted earlier still — the moment `wg set` has read it,
-while the tunnel is being built. That is not housekeeping: `/run` is in the
-container's writable layer, and recreating or migrating the project runs
-`docker commit` over it *without* tearing the tunnel down first. A key that
-lived for the tunnel's lifetime would be baked into the snapshot image and
-copied forward from then on. The kernel keeps its own copy, so nothing is lost.
+The key deletion is not housekeeping: `/run` is in the container's writable
+layer, so `docker commit` bakes whatever is there into the project's snapshot
+image. A key left behind rides that image into every future container.
 
 ## What this deliberately does not do
 
-- **No killswitch.** `iptables` *is* in the image, so one is buildable — this
-  is a deliberate omission, not a missing dependency. Blocking non-tunnel egress
-  cuts Claude Code's own API traffic the moment the tunnel drops, which ends the
-  session that would otherwise fix it. If the user needs guaranteed egress
-  rather than convenient egress, say so plainly and let them decide, rather than
-  improvising one.
+- **No killswitch.** Blocking non-tunnel egress needs `iptables`, which is not
+  in the image, and would cut Claude Code's API traffic whenever the tunnel is
+  down. If the user needs guaranteed egress rather than convenient egress, say
+  so plainly rather than improvising one — it is a real design decision.
 - **No autostart.** There is no service manager in the container and Triple-C
-  has no start hook, so nothing re-establishes the tunnel on its own. `cron` is
-  in the image and `triple-c-scheduler` runs on it, so a scheduled reconnect is
-  possible if the user wants one — it is just not set up, and a tunnel that
-  reconnects unattended deserves an explicit decision.
+  has no start hook, so nothing can re-establish the tunnel automatically.
 - **Not PIA's desktop client.** `pia-daemon` and `piactl` are installable but
   cannot work headless: the daemon never accepts a client connection without
   the GUI, and `piactl --help` states that connecting requires it. If you find

container/skills/pia-vpn/pia-wg.sh

@@ -27,9 +27,6 @@
 set -euo pipefail
 
 # Not ~/pia-creds: under sudo, HOME is /root.
-# Read by up()'s EXIT trap, which runs after the function's locals are gone.
-SETUP_OK=0
-
 CREDS=${PIA_CREDS:-/home/claude/pia-creds}
 REGION=${PIA_REGION:-us_chicago}
 IFACE=pia0
@@ -91,7 +88,7 @@ preflight() {
 # tunnel captures everything while the exclusions that keep DNS and the Docker
 # host reachable are quietly missing -- and `status` still says "full tunnel".
 add_route() {
-  ip route add "$@" || die "could not add route '$*'"
+  ip route add "$@" || die "could not add route '$*'. Run 'down' to undo the partial setup."
   printf '%s\n' "$*" >> "$STATE/routes"
 }
 
@@ -103,6 +100,11 @@ up() {
   esac
   preflight
 
+  # Always start from a known state. Without this a second `up` overwrites the
+  # saved resolv.conf with PIA's own resolvers, so the later `down` "restores"
+  # those and leaves the container with no working DNS and no way back.
+  down >/dev/null 2>&1 || true
+
   mkdir -p "$STATE"; cd "$STATE"
 
   # `curl -o` creates the file before it knows the request failed, so a plain
@@ -121,14 +123,8 @@ up() {
   u=$(sed -n 1p "$CREDS"); p=$(sed -n 2p "$CREDS")
   [ -n "$u" ] && [ -n "$p" ] || die "$CREDS needs two lines: username, then password"
 
-  # Via stdin, not `-u`. curl does blank the password in its own argv, but only
-  # once it is running: sampling /proc/<pid>/cmdline in a tight loop caught the
-  # plaintext in 3 of 200 tries, in the window between exec and the overwrite.
-  # Small, but this is the permanent account password, and the mechanism to
-  # avoid it entirely is already here for the token.
-  tok=$(printf -- '--user "%s:%s"\n' "$u" "$p" \
-    | run "PIA rejected the credentials in $CREDS, or could not be reached" \
-        curl -sf -m 25 -K - \
+  tok=$(run "PIA rejected the credentials in $CREDS, or could not be reached" \
+    curl -sf -m 25 -u "$u:$p" \
     https://www.privateinternetaccess.com/gtoken/generateToken | jq -r .token)
   [ -n "$tok" ] && [ "$tok" != null ] || die "PIA returned no token - check the credentials in $CREDS"
 
@@ -139,9 +135,10 @@ up() {
   sip=$(echo "$srv" | jq -r .ip); scn=$(echo "$srv" | jq -r .cn)
   [ -n "$sip" ] && [ "$sip" != null ] || die "no WireGuard server for region '$REGION'"
 
-  # The key is generated but NOT written yet -- `down` below deletes wg.priv, and
-  # the teardown has to come after every fetch that can fail.
-  priv=$(wg genkey); pub=$(printf '%s' "$priv" | wg pubkey)
+  # umask, not a later chmod: the file is created under the inherited 0022
+  # otherwise, so the key is world-readable for the moment in between.
+  ( umask 077; priv=$(wg genkey); printf '%s' "$priv" > wg.priv )
+  priv=$(cat wg.priv); pub=$(printf '%s' "$priv" | wg pubkey)
 
   # The token goes in on stdin as a curl config rather than in the argv, where
   # `ps` and /proc/*/cmdline expose it to every process in the container --
@@ -154,32 +151,6 @@ up() {
         --cacert ca.rsa.4096.crt "https://$scn:1337/addKey")
   [ "$(echo "$resp" | jq -r .status)" = OK ] || die "key registration failed: $resp"
 
-  # Only now tear down any previous tunnel. Every network call above this line
-  # can fail, and an earlier version tore down first -- so a failed token fetch,
-  # an unreachable server list, or a refused key registration took a *working*
-  # tunnel with it and silently reverted the container to its real address while
-  # the error talked about credentials. Nothing above this line has touched the
-  # network stack. addKey is the most failure-prone of the three: it reaches one
-  # individual gateway by CN with a pinned certificate.
-  #
-  # It also still does the job it was added for: clearing a stale resolv.conf
-  # backup so a second `up` cannot save PIA's own resolvers over the real ones.
-  down >/dev/null 2>&1 || true
-
-  # From here on the network stack is being modified, so any failure has to put
-  # it back rather than exit half-configured.
-  #
-  # EXIT rather than ERR, and a flag rather than the trap's own exit status: an
-  # ERR trap is not inherited by shell functions without `set -E`, so a failure
-  # inside add_route would not fire it, and `die` exits explicitly, which is not
-  # an error and would not fire it either. EXIT catches both.
-  SETUP_OK=0
-  trap '[ "$SETUP_OK" = 1 ] || { echo "pia-wg: setup failed - rolling back" >&2; down >/dev/null 2>&1 || true; }' EXIT
-
-  # umask, not a later chmod: created under the inherited 0022 otherwise, so the
-  # key would be world-readable for the moment in between.
-  ( umask 077; printf '%s' "$priv" > wg.priv )
-
   : > "$STATE/routes"
   ip link add "$IFACE" type wireguard 2>/dev/null || \
     die "could not create a WireGuard interface." \
@@ -188,12 +159,6 @@ up() {
     peer "$(echo "$resp" | jq -r .server_key)" \
     endpoint "$(echo "$resp" | jq -r .server_ip):$(echo "$resp" | jq -r .server_port)" \
     allowed-ips 0.0.0.0/0 persistent-keepalive 25
-  # The kernel holds the key from here, so the file has no reason to outlive
-  # this line -- and every reason not to: /run is in the writable layer, and a
-  # recreate or migrate runs `docker commit` over it without tearing the tunnel
-  # down first, baking the key into the project's snapshot image. `down` also
-  # removes it, for the case where `up` never got this far.
-  rm -f wg.priv
   ip addr add "$(echo "$resp" | jq -r .peer_ip)/32" dev "$IFACE"
   ip link set "$IFACE" up
 
@@ -226,19 +191,6 @@ up() {
 
     # PIA's resolvers live inside 10/8, so pin them back through the tunnel with
     # /32s -- longer still, so they beat the exclusion just added.
-    # `host.docker.internal` is answered only by the resolver about to be
-    # replaced -- it is not in /etc/hosts. Triple-C hands that name to the
-    # container for the LiteLLM gateway and defaults host-side Ollama and custom
-    # endpoints to it, so losing it takes the project's model backend with it.
-    # The *route* to it is already excluded above; only the name needs pinning.
-    # Resolve it with the old resolver and write it into /etc/hosts first.
-    local hdi
-    hdi=$(getent ahostsv4 host.docker.internal 2>/dev/null | awk '{print $1; exit}')
-    if [ -n "$hdi" ]; then
-      cp /etc/hosts "$STATE/hosts.bak"
-      printf '%s host.docker.internal\n' "$hdi" >> /etc/hosts
-    fi
-
     cp /etc/resolv.conf "$STATE/resolv.conf.bak"
     for d in $dns; do add_route "$d/32" dev "$IFACE"; done
     # resolv.conf is a bind mount: write through it, never replace it.
@@ -249,34 +201,12 @@ up() {
     echo "test route only: 1.1.1.1 goes via PIA, everything else unchanged"
   fi
 
-  # A tunnel with no handshake still routes -- into a black hole. Without this
-  # `up --full` would exit 0 having pointed all traffic *and* resolv.conf at a
-  # peer that never answered, and `status` would print "mode: full tunnel".
-  # Demand a number, not just "different from 0". `wg show` prints nothing at
-  # all when the interface has no peer, and writes to stderr when the interface
-  # is gone -- both leave $2 empty, and `[ "" != 0 ]` is true, so the original
-  # form treated a missing tunnel as a completed handshake and exited 0. `until`
-  # suspends both `set -e` and `pipefail`, so nothing else was going to catch it.
-  local waited=0 hs
-  until hs=$(wg show "$IFACE" latest-handshakes 2>/dev/null | awk 'NR==1{print $2}')
-        [[ $hs =~ ^[0-9]+$ ]] && [ "$hs" -gt 0 ]; do
-    waited=$((waited + 1))
-    [ "$waited" -lt 40 ] || die "no handshake from $REGION after 20s"
-    sleep 0.5
-  done
-
-  SETUP_OK=1
-  trap - EXIT
+  sleep 2
   status
 }
 
 down() {
   [ "$(id -u)" = 0 ] || die "run with sudo"
-  # Teardown must finish even if a step fails; a half-rollback is the state this
-  # exists to prevent. Deliberately not inherited from the caller's `set -e`.
-  set +e
-  # First, because removing the interface removes every route that points at it.
-  ip link del "$IFACE" 2>/dev/null
   # Only restore something that actually looks like a resolver file. Restoring
   # an empty or truncated backup leaves the container with no DNS at all, which
   # is worse than leaving the current one alone.
@@ -288,10 +218,6 @@ down() {
     fi
     rm -f "$STATE/resolv.conf.bak"
   fi
-  if [ -f "$STATE/hosts.bak" ]; then
-    cat "$STATE/hosts.bak" > /etc/hosts
-    rm -f "$STATE/hosts.bak"
-  fi
   if [ -f "$STATE/routes" ]; then
     # Reverse order: the specific overrides go before the ranges they sit in.
     tac "$STATE/routes" | while read -r r; do
@@ -299,6 +225,7 @@ down() {
     done
     rm -f "$STATE/routes"
   fi
+  ip link del "$IFACE" 2>/dev/null || true
   # /run is in the writable layer and `docker commit` bakes it into the
   # project's snapshot image, so a key left here rides that image into every
   # future container. Verified: a snapshot already carried one.
@@ -315,24 +242,15 @@ TRACE_DIRECT=https://1.0.0.1/cdn-cgi/trace
 exit_ip() { curl -s -m 20 "$1" | sed -n 's/^ip=//p'; }
 
 status() {
-  # `wg show` needs root; `ip route`/`ip link` do not. Without this guard an
-  # unprivileged run prints "no tunnel up" and then "mode: full tunnel" in the
-  # same breath, and an agent reading the first line re-runs `up`.
-  [ "$(id -u)" = 0 ] || die "run with sudo"
   wg show "$IFACE" 2>/dev/null | grep -E "latest handshake|transfer" || echo "no tunnel up"
 
   # Resolve a name, not an IP literal. A curl to 1.1.1.1 succeeds while DNS is
   # completely broken, which is exactly how a dead resolver goes unnoticed.
   printf 'DNS: '
-  if ! timeout 10 getent hosts api.anthropic.com >/dev/null 2>&1; then
-    echo "BROKEN - cannot resolve api.anthropic.com"
-  elif ! timeout 10 getent hosts host.docker.internal >/dev/null 2>&1; then
-    # PIA's resolvers answer public names happily, so probing only
-    # api.anthropic.com reports "ok" on a container that has just lost the
-    # Docker host -- and with it the LiteLLM gateway and any host-side Ollama.
-    echo "public ok, but host.docker.internal is UNRESOLVABLE (gateway/Ollama backends will fail)"
-  else
+  if timeout 10 getent hosts api.anthropic.com >/dev/null 2>&1; then
     echo "ok (via $(sed -n 's/^nameserver //p' /etc/resolv.conf | tr '\n' ' '))"
+  else
+    echo "BROKEN - cannot resolve api.anthropic.com"
   fi
 
   # Report the exit per mode. In test mode the probe address is itself the one
@@ -356,5 +274,5 @@ case "${1:-}" in
   up) shift; up "${1:-}" ;;
   down) down ;;
   status) status ;;
-  *) sed -n '2,26p' "$0" | sed 's/^# \{0,1\}//'; exit 1 ;;
+  *) sed -n '2,27p' "$0" | sed 's/^# \{0,1\}//'; exit 1 ;;
 esac