fix(launcher): age-gate the temp reaper; drop the publish-dir override

Two contract-level fixes from review of this PR.

The reaper deleted every ccf.pem.* after a publish, which cannot distinguish
an orphan from a CONCURRENT launcher's temp — one that has been written but
not yet renamed. Deleting that makes the peer's renameSync throw a publish
failure we caused, and leaves whichever launcher won first on disk rather
than the current publisher's bytes. Name carries no provenance, so age is the
signal: the write-to-rename window is one small write to the same directory,
microseconds, and a minute of gate is four orders of magnitude of headroom.
Reaping late costs nothing (nothing reads these); reaping early breaks a peer.

CACHE_FIX_CA_TRUST_DIR is removed. The publish path had an override while the
read path was a fixed name, so setting it made this launcher publish where no
builder looks while still consuming the canonical bundle — silently dropping
out of the contract while appearing to implement it. The two paths are halves
of one rendezvous and must move together; CLAUDE_CONFIG_DIR already does that.

The new test asserts both reaper outcomes across ONE launch: an old orphan is
collected and a fresh sibling survives. Mutation-checked in both directions —
removing the age gate reddens the survives assertion, removing the rm reddens
the collected one.

README now also states the boundary explicitly: the guard proves parses +
carries us, never contains only approved writers. This is a cooperative
convention among same-user processes, not a defense against a local attacker,
who could equally replace ccf.pem or the CA dir.

Co-Authored-By: Claude <noreply@anthropic.com>

Author: codeslake

CHANGELOG.md

@@ -4,7 +4,7 @@
 
 ### Fixed
 
-- **`--remote-control` no longer clobbers another component's `NODE_EXTRA_CA_CERTS`.** That variable takes exactly one file, so on a host where something else also MITMs `api.anthropic.com` (a corporate agent, an account-pinning proxy) the last writer won and every other CA was silently untrusted — measured breaking Remote Control inbound. The launcher now publishes its own CA to `${CLAUDE_CONFIG_DIR:-~/.claude}/ca-trust.d/ccf.pem` (own filename only, never a sibling's, rewritten every launch, atomically via temp + `rename`) and reads a merged `ca-trust.pem` if one exists. It never writes the merged bundle: merging needs ambient corporate-root discovery, which is environment-specific and belongs outside this repo. The bundle is used only when every PEM block in it parses **and** one of them is our own CA (compared by DER) — a bundle that is torn or predates our publish is worse than none, since it makes the client distrust the very proxy it is routed through. On a host with no other MITM and no bundle, behavior is byte-identical to before. New opt-in env var: `CACHE_FIX_CA_TRUST_DIR`. See [Coexisting with another MITM](README.md#coexisting-with-another-mitm-on-the-same-machine-ca-trustd).
+- **`--remote-control` no longer clobbers another component's `NODE_EXTRA_CA_CERTS`.** That variable takes exactly one file, so on a host where something else also MITMs `api.anthropic.com` (a corporate agent, an account-pinning proxy) the last writer won and every other CA was silently untrusted — measured breaking Remote Control inbound. The launcher now publishes its own CA to `${CLAUDE_CONFIG_DIR:-~/.claude}/ca-trust.d/ccf.pem` (own filename only, never a sibling's, rewritten every launch, atomically via temp + `rename`) and reads a merged `ca-trust.pem` if one exists. It never writes the merged bundle: merging needs ambient corporate-root discovery, which is environment-specific and belongs outside this repo. The bundle is used only when every PEM block in it parses **and** one of them is our own CA (compared by DER) — a bundle that is torn or predates our publish is worse than none, since it makes the client distrust the very proxy it is routed through. On a host with no other MITM and no bundle, behavior is byte-identical to before. Both paths are fixed names under the config dir with no env override: they are two halves of one rendezvous, so a knob on either half alone would let a participant drop out of the contract while appearing to implement it. See [Coexisting with another MITM](README.md#coexisting-with-another-mitm-on-the-same-machine-ca-trustd).
 
 ### Documentation
 

README.md

@@ -132,12 +132,27 @@ that case, and when no bundle exists at all, the launcher falls back to our own
 CA and behaves exactly as it did before any of this existed. **A host with no
 other MITM and no bundle builder sees no change.**
 
+Both paths are fixed names under `<config>`, deliberately with no env override
+of their own. They are two halves of one rendezvous: a knob on either half alone
+lets a participant publish where no builder looks, or read a file no builder
+writes, while still appearing to implement the contract. `CLAUDE_CONFIG_DIR`
+already relocates the pair, and it moves both halves together.
+
 Note the limit of what a consumer can check: intact, and carries my CA. Whether
 the bundle is *complete* — that no corporate root went missing — is the
 builder's guarantee, not something a reader can verify, because a reader has no
 previous state to compare against and a legitimately small bundle is
 indistinguishable from a narrowed one.
 
+**This is a cooperative convention among same-user processes, not a trust
+boundary.** The check proves *parses, and carries us* — never *contains only
+approved writers*. Anyone who can write `<config>` can hand us a well-formed
+bundle holding our CA plus their own and it will be accepted, exactly as they
+could already have replaced `ca-trust.d/ccf.pem`, the CA dir, or this file. The
+contract defends against components accidentally untrusting each other, which is
+the failure that actually happens; it does not defend against a local attacker,
+who has simpler routes.
+
 #### `CACHE_FIX_DOWNLOAD_REWRITE` breaks `claude update` — leave it off
 
 `CACHE_FIX_DOWNLOAD_REWRITE=on` reads like a pure performance knob. It is not:
@@ -311,7 +326,6 @@ All proxy settings are controlled via environment variables. Set them before sta
 | `CACHE_FIX_PROXY_UPSTREAM` | `https://api.anthropic.com` | Upstream URL. Change to chain another proxy (e.g. `http://localhost:8080`) |
 | `CACHE_FIX_FORWARD_PROXY` | unset | Set to `on` for forward-proxy mode (HTTP CONNECT + selective MITM of the upstream host) so the client points `HTTPS_PROXY` at the proxy instead of `ANTHROPIC_BASE_URL`, keeping Remote Control enabled. See [Forward-proxy mode](#forward-proxy-mode-keeps-remote-control-working). |
 | `CACHE_FIX_CA_DIR` | `~/.claude/cache-fix-ca` | Directory for the forward-proxy CA/leaf cert (generated once on first start). The client trusts `ca.pem` via `NODE_EXTRA_CA_CERTS`. |
-| `CACHE_FIX_CA_TRUST_DIR` | `$CLAUDE_CONFIG_DIR/ca-trust.d` | Where `--remote-control` publishes our CA as `ccf.pem` so another MITM on the same host can merge it. See [Coexisting with another MITM](#coexisting-with-another-mitm-on-the-same-machine-ca-trustd). |
 | `CACHE_FIX_PROXY_TIMEOUT` | `600000` | Request timeout in milliseconds |
 | `CACHE_FIX_EXTENSIONS_DIR` | `proxy/extensions/` | Directory for extension `.mjs` files |
 | `CACHE_FIX_EXTENSIONS_CONFIG` | `proxy/extensions.json` | Extension configuration file |

bin/claude-via-proxy.mjs

@@ -4,7 +4,7 @@ import { fork, spawn } from "node:child_process";
 import { fileURLToPath } from "node:url";
 import { dirname, resolve, join } from "node:path";
 import { homedir } from "node:os";
-import { existsSync, mkdirSync, readdirSync, readFileSync, renameSync, rmSync, writeFileSync } from "node:fs";
+import { existsSync, mkdirSync, readdirSync, readFileSync, renameSync, rmSync, statSync, writeFileSync } from "node:fs";
 import { X509Certificate, randomUUID } from "node:crypto";
 import http from "node:http";
 
@@ -223,8 +223,15 @@ if (remoteControl) {
   // We write EXACTLY ONE path, ca-trust.d/ccf.pem, and never a sibling's.
   // Rewritten every launch, not once: the proxy regenerates its CA whenever
   // caDir is wiped, and a stale pem would advertise a key nothing signs with.
+  //
+  // Fixed name, no env override, for the same reason the merged bundle below has
+  // none: both halves are a rendezvous, and a knob on one half only lets this
+  // launcher publish where no builder is looking while still consuming the
+  // canonical bundle — dropping out of the contract while appearing to implement
+  // it. Relocating the pair is what CLAUDE_CONFIG_DIR already does, and it moves
+  // both sides together.
   const configDir = process.env.CLAUDE_CONFIG_DIR || join(homedir(), ".claude");
-  const caTrustDir = process.env.CACHE_FIX_CA_TRUST_DIR || join(configDir, "ca-trust.d");
+  const caTrustDir = join(configDir, "ca-trust.d");
   try {
     mkdirSync(caTrustDir, { recursive: true });
     const ours = readFileSync(caPem);
@@ -257,8 +264,20 @@ if (remoteControl) {
     // Reap temps orphaned by a kill between the write and the rename. They do
     // not match a *.pem glob so a builder ignores them, but nothing else would
     // ever remove them.
+    //
+    // Age-gated, because a temp is indistinguishable from an orphan by name: a
+    // CONCURRENT launcher has its own ccf.pem.<pid>.<uuid> on disk in the window
+    // between its writeFileSync and its renameSync, and deleting that makes its
+    // rename throw a publish failure we caused. The window is one small write to
+    // the same directory, microseconds; a minute is four orders of magnitude of
+    // headroom and still collects the orphan on the next launch. Deleting late
+    // costs nothing — nothing reads these — while deleting early breaks a peer.
+    const orphanAgeMs = 60_000;
     for (const f of readdirSync(caTrustDir)) {
-      if (f.startsWith("ccf.pem.")) try { rmSync(join(caTrustDir, f)); } catch { /* raced */ }
+      if (!f.startsWith("ccf.pem.")) continue;
+      const p = join(caTrustDir, f);
+      try { if (Date.now() - statSync(p).mtimeMs > orphanAgeMs) rmSync(p); }
+      catch { /* raced: someone renamed or removed it first */ }
     }
   } catch (e) {
     // Non-fatal: publishing is how OTHERS trust us. This session only needs its

test/proxy-wrapper.test.mjs

@@ -4,7 +4,7 @@ import { fork } from "node:child_process";
 import { fileURLToPath } from "node:url";
 import { dirname, resolve, join } from "node:path";
 import { tmpdir } from "node:os";
-import { closeSync, existsSync, fstatSync, mkdirSync, mkdtempSync, openSync, readFileSync, readdirSync, statSync, writeFileSync } from "node:fs";
+import { closeSync, existsSync, fstatSync, mkdirSync, mkdtempSync, openSync, readFileSync, readdirSync, statSync, utimesSync, writeFileSync } from "node:fs";
 import http from "node:http";
 
 const __dirname = dirname(fileURLToPath(import.meta.url));
@@ -467,6 +467,38 @@ describe("launch wrapper (claude-via-proxy)", { concurrency: 1 }, () => {
     assert.ok(begins >= 1, "published pem must contain at least one certificate");
   });
 
+  it("--remote-control reaps an old orphan temp but leaves a concurrent publisher's fresh one alone", async () => {
+    // The reaper cannot tell an orphan from a live temp by NAME — both are
+    // ccf.pem.<pid>.<uuid>. A second launcher publishing at the same moment has
+    // written its temp and not yet renamed it; deleting that makes ITS
+    // renameSync throw a publish failure we caused, and leaves whichever
+    // launcher won first on disk rather than the current publisher's bytes.
+    // Age is the only signal available: the write-to-rename window is one small
+    // write to the same directory, so anything older than the gate is genuinely
+    // abandoned and anything younger may be in flight.
+    //
+    // Both fixtures exist in the same directory across one launch, so the test
+    // fails if the reaper is unconditional (fresh one dies) OR absent (old one
+    // survives) — one launch, two opposite outcomes.
+    const configDir = mkdtempSync(join(tmpdir(), "cfftrust-"));
+    const trustDir = join(configDir, "ca-trust.d");
+    mkdirSync(trustDir, { recursive: true });
+    const stale = join(trustDir, "ccf.pem.99999.aaaaaaaa-orphan");
+    const fresh = join(trustDir, "ccf.pem.99998.bbbbbbbb-inflight");
+    writeFileSync(stale, "# abandoned by a kill between write and rename\n");
+    writeFileSync(fresh, "# a concurrent launcher's temp, not yet renamed\n");
+    // Backdate past the gate. Real time cannot be used — the gate is a minute and
+    // a test may not sleep for one.
+    const longAgo = new Date(Date.now() - 3600_000);
+    utimesSync(stale, longAgo, longAgo);
+
+    const { code, err } = await runWrapper('process.stdout.write("OK\\n")', { CLAUDE_CONFIG_DIR: configDir });
+    assert.equal(code, 0, `Expected exit 0, got ${code}. stderr: ${err}`);
+
+    assert.ok(!existsSync(stale), "a temp older than the gate is abandoned and must be reaped");
+    assert.ok(existsSync(fresh), "a temp younger than the gate may belong to a live publisher and must survive");
+  });
+
   it("--remote-control ignores a merged bundle that does NOT contain our own CA", async () => {
     // The dangerous case, and worse than falling back: the bundle exists and is
     // non-empty, so a size-only gate accepts it — but it was built BEFORE we