P14 Substack API drift early warning

[edithatogo]

Objective

Provide early warning when live Substack HTML or authenticated read-only JSON contracts drift.

Scope

• Scheduled read-only canary every six hours
• Secret-safe evidence and alert delivery
• No publication, draft mutation, or production-account use
• Conductor phase P14 with track T14-01

[edithatogo]

Implementation merged via #467 at 147a9c3510cf7c1a5ed3a021bf5a9101c33a2035 with all available Actions green, including Mutation, CodeQL, strict TypeScript, audit/secret scan, SBOM, compatibility, Quality, Smoke, and deterministic assurance. All PR comments/reviews were inspected; no actionable findings remained.

Activation remains intentionally open and requires:

• dedicated non-production *.substack.com tester publication
• SUBSTACK_CANARY_URL and reviewed SUBSTACK_CANARY_CONTRACT_JSON variables
• rotated SUBSTACK_TEST_COOKIE secret
• at least one Slack, Discord, or PagerDuty alert secret
• successful manual first-run receipt

No live write or credential fabrication was performed.

[edithatogo]

Closed as completed during the T17-01 canonical hierarchy reconciliation; implementation evidence remains in the merged track history.

[edithatogo]

Reopened by programme reconciliation: implementation is merged, but live tester-account activation, scheduled-run, and alert-path evidence remain open in #532.