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reverse-engineering-anything/docs/specs/agent-environments/scenario-timing/spec.md
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morluto 63220edcc3 fix(environment)!: withhold clock writes without an anchor
Keep missing or ambiguous scenario request durations unknown, retain learned clock rules, and withhold plans that cannot generate an observed clock. Refuse such writes in older imported states before changing state or generators.

BREAKING CHANGE: The write-plan reason can now be unknown-clock; strict clients must accept the new output value.

Validated state, CLI and advertised MCP workflows, documentation, and focused clock and cleanup regressions.
2026-10-27 05:19:35 +08:00

2.2 KiB

Time browser scenario records

Outcome

Browser scenario network events record no times, so every record a scenario projects is untimed. The environment-state view then orders records by position, detects no overlapping requests and learns no write clock: an update whose response carries a modification time the application sets is withheld as unexplained-change however it is recorded, while a HAR of the same session serves it with a clock rule.

Scenario network events now record when each request was observed and how long the browser took, and scenario records carry them as HAR entries do, so a scenario capture learns the clock a HAR does.

Requirements

  • Each request event carries observed_at, the ISO wall-clock time the provider observed the request start; Playwright reports the browser's start only once a request ends.
  • Each request-finished and request-failed event carries started_at, the browser's wall-clock start (timing().startTime > 0), and elapsed_ms, its time from that start to the end of the response (timing().responseEnd >= 0), when the browser reports them.
  • The fields are optional in the schema, so Evidence captured before them still parses and is read exactly as before. REA versions before them refuse Evidence that carries them.
  • Scenario records take startedDateTime from the transaction's single finished or failed event's started_at, else from observed_at, and time from its elapsed_ms, omitted without a unique reported duration, and say so in a limitation. An explicit zero remains zero. Complete starts establish the recorded-start-time timeline; a write clock also requires known completions.
  • Scenario comparisons ignore both fields, as a committed built-in rule (ignore_network_request_timing).
  • The added metadata is charged to the event budgets as other metadata is.

Non-goals

  • No change to HAR captures, to how the state uses times, or to what a record's timing means for overlap or clock rules.
  • No retroactive timing of captures made before this change.
  • No browser start for a request that never ended: its record starts at observed_at, which can trail the browser's start by tens of milliseconds while the provider reads other responses, with no duration.