Merge branch 'worktree-agent-a63474e92b05425a5'

# Conflicts:
#	Cargo.lock
#	Cargo.toml

tickets/003-metric-bucket-derivation.md

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+# 003 — Metric bucket derivation
+
+## Summary
+
+Apply metric declarations to log lines and populate `IndexKey::Bucket` /
+`DataValue::BucketValue` entries, both retroactively (backfill already-ingested logs
+when a metric is declared) and going forward (index each new log against all current
+metric declarations as it's ingested).
+
+## Scope
+
+- On `MetricDeclaration` add: scan the existing `IngestedLog` range, run the metric's
+  regex against each log's text, and for each match compute the labeled `Bucket` key
+  (`metric_name` + `labels: BTreeMap<String, MetricPrimitive>`) and append
+  `(sequence, timestamp, value)` to that bucket's `BucketValue`.
+- On new log ingest: run all currently-declared metrics' regexes against the line and
+  update buckets incrementally, same as backfill.
+- Decide bucket cardinality behavior: a single log line can match multiple metrics: it
+  should update all matching buckets. Document how differing label sets from the same
+  metric become distinct `Bucket` keys (labels are part of the key, so this falls out
+  naturally from `BTreeMap` — just needs the insert-or-append logic).
+- This is the piece that makes `MetricPrimitive`, `DataValue::BucketValue`, and the
+  `Bucket` index range (currently defined but never populated) actually load-bearing.
+
+## Acceptance criteria
+
+- Declaring a metric against a log stream that already has matching lines populates
+  buckets for those lines without needing new input.
+- Ingesting a new log line after metrics are declared updates the relevant buckets
+  live.
+- A log line matching zero metrics doesn't touch the bucket range.
+- Bucket values preserve insertion order / are queryable by sequence and timestamp
+  range (needed by [004](004-metrics-api.md) and dashboards).
+
+## Depends on
+
+- [002 — Metric declarations](002-metric-declarations.md)