chore: archivace OpenSpec změny add-daily-api-monitor

Úkol 4.3 (ruční běh po merge do main) splněn: běh 37059874538 skončil
podle návrhu červeně kvůli rozbitému oai_dc na api.aiscr.cz/2.2/oai
a založil issue #89. Změna přesunuta do archivu (--skip-specs).

Připraveno s pomocí AI (Claude).

openspec/changes/archive/2026-10-02-add-daily-api-monitor/specs/api-monitoring/spec.md

@@ -0,0 +1,63 @@
+# Spec Delta
+
+## Purpose
+
+Detects changes of the digiarchiv / AMČR OAI API that break or alter what
+the AMČR Viewer plugin relies on, within a day of their deployment, and
+reports them where maintainers see them.
+
+## ADDED Requirements
+
+### Requirement: The API contract is checked daily
+The repository SHALL run, once a day and on manual dispatch, a check of
+every API endpoint, parameter and response field the plugin uses, without
+credentials, against the production API.
+
+#### Scenario: Scheduled run
+- **WHEN** the daily schedule fires on the default branch
+- **THEN** both the contract test and the live plugin test run against the production API and their results are published in the run summary
+
+#### Scenario: Manual run on another branch
+- **WHEN** a maintainer dispatches the workflow on a non-default branch
+- **THEN** the tests run against that branch's plugin code and no issue is opened, updated or closed
+
+### Requirement: Checks follow the plugin, not the API documentation
+The contract test SHALL send requests built the way the plugin builds them
+and check the response keys, value types and shapes the plugin reads. The
+live plugin test SHALL call the plugin's own codelist and download
+functions.
+
+#### Scenario: Facet shape changes
+- **WHEN** the API returns facet items in a shape different from the one recorded in the contract test
+- **THEN** the contract test reports a drift naming the facet field and the old and new shape
+
+#### Scenario: Plugin function returns nothing
+- **WHEN** a plugin codelist set or data download returns zero items for an input that returned items before
+- **THEN** the live plugin test fails and names the set or data type
+
+### Requirement: Outages are not reported as API changes
+A request that times out, fails to connect or returns HTTP 5xx SHALL be
+retried; if it still fails, the check SHALL be reported as unavailable,
+separately from failures and drifts.
+
+#### Scenario: Server maintenance
+- **WHEN** digiarchiv is unreachable during the whole run
+- **THEN** the run reports the affected checks as unavailable and no issue is opened
+
+### Requirement: Breaks are reported through one tracking issue
+A run with a failure or drift on the default branch SHALL open an issue
+labelled `api-monitor`, or update the open one, with the deployed
+digiarchiv version and the list of failing checks. A clean run SHALL close
+the open issue.
+
+#### Scenario: First failing run
+- **WHEN** a scheduled run fails and no open `api-monitor` issue exists
+- **THEN** a new issue is opened with the deployed version, failing checks and a link to the run
+
+#### Scenario: Repeated identical failure
+- **WHEN** a scheduled run fails with the same set of FAIL/DRIFT checks as the open issue already lists, regardless of which checks are unavailable
+- **THEN** no new issue and no new comment is created
+
+#### Scenario: Recovery
+- **WHEN** a scheduled run passes while an `api-monitor` issue is open
+- **THEN** the issue is closed with a comment linking the passing run