fix: fail closed on instance health endpoint when token unset

[dan2k3k4]

Makes the instance health endpoint reject requests when no health token is configured, instead of processing them unauthenticated.

Greptile Summary

This PR hardens the instance health endpoint to fail closed when POLYDOCK_HEALTH_TOKEN is not configured, replacing the previous behaviour that allowed unauthenticated requests through with only a warning log. The fix is a targeted, single-file security change with a corresponding test update.

• Controller (PolydockInstanceHealthController.php): Replaces the if ($expectedToken) guard (which allowed unconfigured deployments to accept health updates silently) with an explicit ! is_string($expectedToken) || $expectedToken === '' check, returning 503 with a log error instead of passing the request through. The comment explains why is_string() is used — it also covers the false boolean that Laravel's env parser can produce.
• Test (InstanceHealthApiTest.php): Renames and rewrites the "no token configured" test to assert a 503 response and verify the instance status is not mutated, with the instance pre-set to a different status so the assertion is non-vacuous.

Confidence Score: 5/5

Safe to merge — the change correctly closes an unauthenticated access path and all previous review concerns are addressed in the current code.

The auth guard now correctly rejects every request when the token is absent or non-string (null, boolean false, empty string), returning 503 before any instance lookup or status mutation occurs. The test update makes the 'status not mutated' assertion meaningful by starting from a distinct state. No regression risk on the authenticated path — existing tests for valid and invalid tokens remain unchanged and still pass.

No files require special attention.

Important Files Changed

Filename	Overview
app/Http/Controllers/Api/PolydockInstanceHealthController.php	Fail-closed guard replaces the old open-by-default path; correctly handles null, false, empty string, and "0" token values via is_string() + strict empty-string check.
tests/Feature/Api/InstanceHealthApiTest.php	No-token test updated to expect 503 and assert status immutability; instance now starts in RUNNING_UNHEALTHY so the unchanged-status assertion is non-vacuous.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[Health Request] --> B{is_string\nexpectedToken\nAND not empty?}
    B -- No\nnull / false / '' --> C[Log::error\n'not configured']
    C --> D[503 Service Unavailable\nfail-closed]
    B -- Yes\ntoken is set --> E{is_string\nsuppliedToken\nAND hash_equals?}
    E -- No --> F[401 Unauthorized]
    E -- Yes --> G[Find instance\nvalidate status]
    G --> H{Instance found\nand status valid?}
    H -- No --> I[400 / 404]
    H -- Yes --> J[Update instance status\n200 OK]

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flowchart TD
    A[Health Request] --> B{is_string\nexpectedToken\nAND not empty?}
    B -- No\nnull / false / '' --> C[Log::error\n'not configured']
    C --> D[503 Service Unavailable\nfail-closed]
    B -- Yes\ntoken is set --> E{is_string\nsuppliedToken\nAND hash_equals?}
    E -- No --> F[401 Unauthorized]
    E -- Yes --> G[Find instance\nvalidate status]
    G --> H{Instance found\nand status valid?}
    H -- No --> I[400 / 404]
    H -- Yes --> J[Update instance status\n200 OK]

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_{Reviews (3): Last reviewed commit: "fix: fail closed on instance health endp..." | Re-trigger Greptile}