* fix: authenticate slack callback payload with per-workspace hmac
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
* test: regression tests for unauthenticated slack callback decryption
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
* fix: verify slack submission signature before resume + close workspace oracle
Addresses review: verify private_metadata HMAC before handle_resume_action so a
tampered/unsigned submission is rejected up front, and map get_workspace_key
failure to the generic 401 so the status code is not a workspace-existence oracle.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
* fix: domain-separate slack payload hmac from resume-secret hmac
Both MAC families key Hmac<Sha256> on the same per-workspace key; resume secrets
are distributed to approvers in resume URLs, so add a fixed domain tag
(slack_payload_v1) to the slack payload MAC to make the two non-interchangeable
by construction rather than by byte-layout coincidence.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
