fix(client-runtime): incompatible hosts no longer switch environments off for good

[vitalyiegorov]

A protocol mismatch could persist an environment as switched off, leaving it disconnected after the host became compatible again. Compatibility now pauses the runtime without overwriting the user’s saved on/off choice. Clearing the block reconnects enabled environments; manually disabled environments remain off. Recreated leases respect the block, and a relaunch does not retain an implicit switch-off. Unsupported environments remain excluded from workspace navigation, load balancing and GitHub routing, including an unsupported primary environment in the settings lists. Paused hosts cannot force strict PR reads or become routing alternatives, preserving the ordinary held-summary path. Mobile’s new-task picker reports client incompatibility instead of incorrectly claiming the connected host has no projects.

Fixes #15051. Maintainer takeover of @vitalyiegorov’s original contribution, preserving the contributor commits and merging current main. Conflicts were adapted to main’s initial supervisor intent and React compiler conventions. Existing persisted-Off entries are deliberately not migrated: they cannot be distinguished from intentional user choices. A stale host descriptor or an already-Off Android entry may therefore need separate diagnosis; this is prevention of new implicit-Off states.

Tests were consolidated in existing files: registry 47 → 45, thread-shell 8 → 9 parameterized cases, with 14 fewer lines overall. Preflight rejection, recovery, relaunch, manual disablement, recreated platform leases and unsupported thread visibility are covered without sleeps. Five focused suites pass: 77 → 76 tests. Main fails the three regression assertions; rebuilt head passes all 76. The existing PR-routing table covers disabled and enabled-unsupported alternatives: 69 → 71 tests, with the unsupported case failing before the routing guard because it forced allowStale: false (27 ms, no timer). Routing, registry and thread-shell suites pass all 125 cases after that fix. An existing onboarding assertion was updated from implicit Off to preserved enabled/unsupported state, with no new test cases; onboarding remains 16 tests. The six related routing/registry/thread-shell/onboarding/host-update/compatibility suites pass all 148 tests. Another 47 tests pass in eight existing mobile suites after the new-task compatibility message fix. Scoped client-runtime, web and mobile typechecks, touched lint, format and whitespace checks pass.

Verification uses headless Linux Chromium, isolated worktree state and a second real local server authenticated with a disposable bearer credential. The app connects to that server; a test-only command invokes the real registry’s compatibility service to simulate rejection and clearance. On main, clearance leaves the row Off. On the rebuilt head, it reconnects over the real socket. Manual switch-off remains Off after another block/clear cycle; a page relaunch while blocked reconnects to the compatible server. Actual wire-protocol mismatch, an in-app host upgrade and live Relay discovery were not exercised in this browser flow; their runtime paths were reviewed and focused tests cover preflight rejection. Both captures use the same synthetic environment, initial enabled choice, 1280×800 viewport and scroll. A browser-only fallback font replaces missing container fonts. Baseline production sources are main 1451e7cb23; web proof was captured at 31f453439f. Subsequent commits correct the mobile new-task incompatibility message and GitHub-routing eligibility; neither changes the captured Connections recovery behavior. No fixtures or evidence assets are committed.

Before — compatibility clears, environment stays Off

After — compatibility clears, enabled environment reconnects

Runtime block and recovery recording

Four independent full-diff review rounds were run with Claude and Codex. Confirmed findings were fixed: mobile new-task compatibility messaging, unsupported PR-routing alternatives forcing strict reads, and an obsolete onboarding assertion. Both fourth-round reviews found no blockers at 4622dfb415; Claude independently reran all 148 related tests at that head. Optional preselection/status/error-detail UX and unreachable error-type cleanup remain outside this fix.

CI's first web run failed two unchanged browser tests (workflow syntax highlighting and attachment HTML source preview). A fresh agent ran both files headlessly on base and head: 6/6 pass on each. Their tests, components and lockfile are unchanged. This supports a possible timing failure without establishing its cause. The failed jobs were rerun once: attachment preview passed, but workflow highlighting still failed, with 8,047 web tests passing. CI remains blocked on Test Web and its aggregate Check. The unchanged test uses the default one-second wait for a Suspense-loaded WASM highlighter; source tracing found no confirmed takeover regression. The next diagnostic is to capture highlighter readiness at failure, then await that milestone explicitly if confirmed. No unrelated renderer/test changes or further blind reruns were made. Build/typecheck, lint, server tests, other package tests, current Macroscope and CodeRabbit checks passed. An earlier cancelled native fingerprint run was superseded by a successful run.

Native macOS, Windows, Electron desktop, iOS, Android and live remote Relay/tunnel sessions were not verified. The shared runtime change serves web and mobile; native recovery still needs device verification. This PR remains unmerged.

Implementation: Codex GPT-6.1 Sol; tests: Codex GPT-6 Astra (high); adversarial review: Claude Opus 5.5 and Codex GPT-6 Sol through T3 Code delegated tasks. Integrated and verified in T3 Code using the Codex harness.

[macroscopeapp]

Approvability

Verdict: Approved at 4622dfb

Macroscope's review found this PR approvable — This is a focused compatibility-state bug fix that preserves users' saved connection choices, excludes unsupported hosts from active work, and reconnects them after recovery. The runtime changes are cohesive and supported by targeted tests across registry, routing, navigation, onboarding, web, and mobile behavior.

^{You can add or adjust custom eligibility rules. Learn more.}

[coderabbitai]

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Reviewing files that changed from the base of the PR and between a96277c and c3a8d6f.

📒 Files selected for processing (1)

• apps/web/src/components/settings/ConnectionsSettings.tsx

🚧 Files skipped from review as they are similar to previous changes (1)

• apps/web/src/components/settings/ConnectionsSettings.tsx

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📝 Walkthrough

Unsupported protocol states now pause connections without changing the saved enabled choice. When compatibility returns, enabled environments can reconnect. Unsupported environments are excluded from load-balancing and GitHub-sharing lists.

Changes: Connection compatibility handling

Layer / File(s)	Summary
Track compatibility separately from enabled state packages/client-runtime/src/connection/catalog.ts, packages/client-runtime/src/connection/registry.ts, packages/client-runtime/src/connection/registry.test.ts	The registry connects only enabled, supported entries. Compatibility blocks preserve the enabled choice, and clearing a block reconnects an enabled environment. Tests cover discovery, preflight rejection, relaunch, and platform refresh.
Exclude unsupported environments from eligible lists packages/client-runtime/src/state/connections.ts, apps/web/src/components/settings/ConnectionsSettings.tsx	Enabled environment IDs and the settings list now exclude unsupported environments. The primary environment remains first.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix · Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to c3a8d

Unsupported connections remain visible in Settings but are excluded from eligible lists. No issue identified here prevents merging after normal checks.

Security architecture risk: 🔵 Low · up to a9627

Incompatible hosts remain paused without overwriting the user's saved choice. The reviewed routing controls still restrict operational use, and no new security vulnerability was established. Some interruption and recovery behavior remains unverified.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — The demonstrated exposure change is renewed connection attempts to registered environments whose enabled choice remains on. The reviewed change does not itself grant GitHub routing permission or broaden the Settings list of saved routing candidates.

Trust Boundaries and Controls

• observed — Operational load balancing independently requires a connected environment and an eligible provider. GitHub routing requires explicit permissions on both endpoints, checks SSH connection identity, and skips alternative destinations without a session. Visibility in Settings is not the sole operational control.

Resilience and Maintainability Implications

• observed — Platform environments remain host-reconciled rather than persisted through the saved enablement flag. Settings excludes primary and desktop-local platform targets from saved switches, and platform disappearance has a separate removal path.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 5 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Linked Issues check		Issue [#15051] requires an incompatible environment to retain the user's enabled choice, reconnect when compatibility returns, and remain off if the user switched it off. The PR summary reports that c…
Out of Scope Changes check		The changes to enabledEnvironmentIds, load-balancing and GitHub-sharing eligibility, registry documentation, and registry tests support keeping unsupported environments disconnected and excluded fro…
Title check		The title clearly identifies the client-runtime fix: incompatible hosts no longer persist an environment as switched off.
Description check		The description is substantially complete. It explains the problem and change, links the related issue and original contribution, documents extensive focused verification, includes screenshots and a r…

Full details: Linked Issues check

Explanation

Issue [#15051] requires an incompatible environment to retain the user's enabled choice, reconnect when compatibility returns, and remain off if the user switched it off. The PR summary reports that compatibility state no longer changes enabled, connection requires enabled && !unsupportedReason, and clearing the block reconnects an enabled environment. Reported tests cover rejection without persisting off, reconnect after compatibility clears, relaunch, and preserving a user-selected off state.

Full details: Out of Scope Changes check

Explanation

The changes to enabledEnvironmentIds, load-balancing and GitHub-sharing eligibility, registry documentation, and registry tests support keeping unsupported environments disconnected and excluded from active routing while retaining their enabled choice. The whole-PR summary identifies no unrelated changes.

Full details: Description check

Explanation

The description is substantially complete. It explains the problem and change, links the related issue and original contribution, documents extensive focused verification, includes screenshots and a recording for the UI change, states limitations, and identifies the models and harness used. It does not follow the template headings and does not include a direct link to an explicit maintainer approval comment.

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[vitalyiegorov]

@coderabbitai Thanks. On the two warnings and the hardening note:

• Description check: this ran before the body was updated. Scope now links the triage of [Bug]: Remote environments stay switched off after a protocol mismatch, even once the host is updated #15051, which confirms the bug and this intended behavior: [Bug]: Remote environments stay switched off after a protocol mismatch, even once the host is updated #15051 (comment)
• Docstring coverage: the new shouldConnect and the changed enabledEnvironmentIds both have doc comments. setCompatibility keeps its inline note. Repo guidance is not to add comments just to hit a coverage number.
• Cancellation consistency: these steps already run under the per-environment withLeaseLock, in the same order as before. This PR only stops writing enabled and adds a reconnect, so it doesn't introduce that concern.

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🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
set -euo pipefail
gh pr view 15052 --repo pingdotgg/t3code --json body --jq '.body'
gh api repos/pingdotgg/t3code/issues/comments/5966129266 --jq '.body'
ast-grep outline packages/client-runtime/src/connection/registry.ts --items all --match 'shouldConnect|setCompatibility|withLeaseLock' --view expanded
ast-grep outline packages/client-runtime/src/state/connections.ts --items all --match enabledEnvironmentIds --view expanded
rg -n -C 18 'shouldConnect|setCompatibility|withLeaseLock' packages/client-runtime/src/connection/registry.ts
rg -n -C 12 'enabledEnvironmentIds' packages/client-runtime/src/state/connections.ts
gh pr diff 15052 --repo pingdotgg/t3code -- packages/client-runtime/src/connection/registry.ts 2>/dev/null || gh api repos/pingdotgg/t3code/pulls/15052/files --jq '.[] | select(.filename == "packages/client-runtime/src/connection/registry.ts") | .patch'

Length of output: 30684

---

@vitalyiegorov Thanks for the clarification and guidance. I checked the current description, linked triage, and code.

• Description check: The updated body links the triage of #15051 and states the intended behavior. The warning is stale. Maintainer approval of the fix direction remains separate.
• Docstring coverage: shouldConnect and enabledEnvironmentIds have doc comments. setCompatibility explains the behavior inline. Extra comments solely to meet a coverage number are not warranted.
• Cancellation consistency: setCompatibility retains the per-environment withLeaseLock and the existing update order. The diff does not establish a new cancellation defect, so the PR-specific hardening note is not warranted.

I withdraw both warnings and the hardening note.

---

✏️ Learnings added

Learnt from: vitalyiegorov
URL: https://github.com/pingdotgg/t3code/pull/15052

Timestamp: 2026-10-03T06:00:13.284Z
Learning: In pingdotgg/t3code, repository guidance is not to add comments solely to meet a docstring coverage number. Evaluate whether TypeScript functions have useful documentation, including existing doc comments and inline explanations, rather than requesting redundant comments to satisfy a coverage threshold.

---

Learnt from: vitalyiegorov
URL: https://github.com/pingdotgg/t3code/pull/15052

Timestamp: 2026-10-03T06:00:13.284Z
Learning: In pingdotgg/t3code, issue #15051 confirms that protocol incompatibility is runtime state, not a persisted user switch-off. In packages/client-runtime/src/connection/registry.ts, EnvironmentRegistry.setCompatibility must preserve enabled and the persisted switched-off list, disconnect while unsupported, and reconnect when compatibility clears only if enabled remains true. Previously persisted switch-offs cannot be safely migrated because they cannot be distinguished from explicit user choices.

Note: Learnings are effective only in the context of similar code segments. To apply general coding guidelines, please configure review instructions. You can manage existing learnings in the app.

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Actionable comments posted: 1

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Inline comments:
Review comments at @apps/web/src/components/settings/ConnectionsSettings.tsx:
- Around line 1991-1993: Update the environment list construction in
ConnectionsSettings so primaryEnvironment is included only when its connection
phase is not unsupported. Preserve the existing saved-environment filtering and
supported-primary behavior.

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📥 Commits

Reviewing files that changed from the base of the PR and between 812322d and a96277c.

📒 Files selected for processing (4)

• apps/web/src/components/settings/ConnectionsSettings.tsx
• packages/client-runtime/src/connection/catalog.ts
• packages/client-runtime/src/connection/registry.test.ts
• packages/client-runtime/src/connection/registry.ts

🚧 Files skipped from review as they are similar to previous changes (1)

• packages/client-runtime/src/connection/catalog.ts

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Dismissing prior approval to re-evaluate c3a8d6f

[coreldh]

Following this from #20416 / #15051 on Android 2.0 with a macOS 0.1.0 Stable host over T3 Connect. I understand this PR prevents new persisted-Off states but does not migrate existing ones, and mobile-on-device was not checked. Is #19251 now the intended integration path for Android recovery as well? My saved entry remains stuck on the old host version / “Client not supported” despite the direct descriptor reporting protocol 2. I haven't tested this PR.

[juliusmarminge]

Taking over this one as maintainer for batch ssh-relay-remote-06. I will preserve the contributor commits, merge current main, and rebuild the runtime compatibility pause without overwriting saved on/off choices. Thanks @vitalyiegorov for tracing the persistent-Off regression. Existing persisted-Off entries remain outside this fix because they cannot be distinguished from an intentional user choice.

[juliusmarminge]

@coreldh This takeover prevents new implicit-Off states while preserving intentional switch-off choices. It does not migrate existing persisted-Off entries or repair stale discovery descriptors, and I have not verified Android or the separate integration path you mentioned. The updated description includes the exact Linux browser/test proof and native verification limits. Thanks for keeping those recovery cases distinct.

Dismissing prior approval to re-evaluate 4622dfb