fix(cli,core,studio): close 15 review findings + 2 R5 blockers

R5 blockers
- Negative install-state latch was cached for the process lifetime, but
  only `true` is monotonic across processes. A long-lived preview server
  held a stale `false` and could re-enrol after another process tripped
  the breaker. Only the positive is cached now; `false` re-reads.
- The real breaker writer used writeConfig(), which collapses
  {ok:true, mirrored:false} to success, so a run that mirrored nothing
  reported done with the latch only on the erasable store. It consumes
  writeConfigWithResult and retries until both stores carry it.

Bucketing integrity
- Storage-restricted Studio profiles all bucketed on the literal
  "anonymous": computed against the shipped hash, 100% of them were
  enrolled in calibration-50 rather than 50%, and they merged into one
  PostHog person. Per-session random id instead — persists nothing.
- bucketSeed had read/write authority backwards: install-state is
  write-once authoritative, but readConfig took config.json's blindly, so
  the stores could hold different seeds until a re-mint flipped every
  cohort. Merged on read, like the latch.
- An unwritable ~/.hyperframes with no config.json re-minted per call,
  re-rolling the seed on every command, and the "cohorts will not be
  stable" warning was unreachable on that path.
- A corrupt PRE-MOVE state file was never deleted, so a machine reset
  with `rm -rf ~/.hyperframes` reported predecessorFound/stateFileCorrupt
  forever — poisoning the exact metric this work exists to produce.

Opt-out honoring
- CLI canary decisions memoized per process, so `hyperframes telemetry
  disable` during a running preview server was ignored for hours while
  the server kept serving pre-opt-out decisions. The memo is keyed on the
  telemetry posture.
- shouldTrack() memoized, contradicting policy.ts's documented "not
  memoized" contract that policy.test.ts asserts.
- The Studio override path resolved the bucket unit eagerly as an
  argument, minting and PERSISTING a tracking id for an opted-out profile
  — a value evaluateCanary discards unread.
- Storage reads could throw out of telemetry into a post-commit catch
  block, reporting an already-committed edit as failed.
- readConfig printed an unsilenceable stderr warning on every invocation
  for installs that opted out of telemetry entirely.

Host split
- isLoopbackHost rejected 0.0.0.0, so the documented
  HYPERFRAMES_PREVIEW_HOST LAN mode silently lost CLI→Studio identity
  stitching and split one user across two PostHog persons. Identity is
  now allowed when the operator explicitly opted into LAN binding.
- Corrected the comment claiming the guard refuses spoofed Hosts: a
  non-browser client sets Host freely. It is a browser DNS-rebinding
  mitigation, not access control, and now says so.

Semantics and test hygiene
- percentage:100 did not mean everyone — exclude and no_unit_id sat above
  the fast path, so the registry's "delete the entry at 100" step was an
  unstaged flip for CI and seedless installs.
- CLI cohort adoption returned before evaluateCanary, dropping Studio's
  own webdriver exclusion.
- overdueCanaries() was asserted against wall-clock time, so the whole
  core suite would go red on 2026-09-15 for every unrelated PR; and `>`
  against midnight made a canary overdue ON its sunset date.
- Statistical assertions ran on unseeded randomUUID() populations tight
  enough to fail ~1 run in 200. Seeded.

Also: broke a config -> policy -> transport -> config import cycle by
moving POSTHOG_API_KEY to a leaf module.

Tests: 2347 CLI (bundle absent), 3153 Studio, 1450 core. Fault injection
covers the latch, seed authority, LAN identity, webdriver exclusion and
the anonymous-bucket fix. Two pre-existing tests asserted behaviour these
findings identify as wrong (shouldTrack memoization, 100%-excludes-CI)
and were rewritten with the reasoning stated.

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

packages/cli/src/commands/render.ts

@@ -66,6 +66,7 @@ import {
   readConfigFresh,
   recordRecentRender,
   writeConfig,
+  writeConfigWithResult,
   type HyperframesConfig,
 } from "../telemetry/config.js";
 import { shouldTrack } from "../telemetry/client.js";
@@ -1253,13 +1254,23 @@ function resolveDeParallelRouterOutcome(job: RenderJob): string | undefined {
  */
 function persistDeParallelRouterTrialFired(): boolean {
   const MAX_ATTEMPTS = 3;
+  let mirrored = false;
   for (let attempt = 0; attempt < MAX_ATTEMPTS; attempt++) {
     const config = readConfigFresh();
-    if (config.deParallelRouterTrialFired) return true;
+    // Both stores must carry the latch, not just config.json. Checking only
+    // the config let a run stop early after a failed mirror — and config.json
+    // is the copy a stale writer or a re-mint can erase, so the durable one
+    // is exactly the one that was missing. The read side merges install-state
+    // back in, so the two together are what make the trip survive.
+    if (config.deParallelRouterTrialFired && mirrored) return true;
     config.deParallelRouterTrialFired = true;
-    if (!writeConfig(config)) return false;
+    const result = writeConfigWithResult(config);
+    if (!result.ok) return false;
+    mirrored = result.mirrored !== false;
+    if (mirrored) return true;
+    // Config landed but the mirror did not — retry rather than report success.
   }
-  return Boolean(readConfigFresh().deParallelRouterTrialFired);
+  return false;
 }
 
 /**