diff --git a/agent-task/m-scheduled-market-data-refresh/02_retry_backfill/CODE_REVIEW-local-G04.md b/agent-task/m-scheduled-market-data-refresh/02_retry_backfill/CODE_REVIEW-local-G04.md
new file mode 100644
index 0000000..e0e07a0
--- /dev/null
+++ b/agent-task/m-scheduled-market-data-refresh/02_retry_backfill/CODE_REVIEW-local-G04.md
@@ -0,0 +1,159 @@
+<!-- task=m-scheduled-market-data-refresh/02_retry_backfill plan=0 tag=BACKFILL -->
+
+# Code Review Reference - BACKFILL
+
+> **[IMPLEMENTING AGENT — READ FIRST] Filling in this file is the mandatory final step of implementation.**
+> The task is NOT complete until every implementation-owned section below is filled in.
+> Complete the `구현 체크리스트`; the final checklist item is mandatory before saving.
+> Fill implementation-owned sections, then stop with active files in place and report ready for review.
+> If implementation is blocked by a selected SDD decision or selected Milestone `구현 잠금 > 결정 필요` item, fill `사용자 리뷰 요청` with linked evidence and stop with active files in place; code-review decides whether to write `USER_REVIEW.md`.
+> Do not ask the user directly, present choices in chat, or call `request_user_input` during implementation.
+> Finalization (`코드리뷰 결과`, log rename, `complete.log`, archive moves, `코드리뷰 전용 체크리스트`) is review-agent-only.
+
+## 개요
+
+date=2026-06-21
+task=m-scheduled-market-data-refresh/02_retry_backfill, plan=0, tag=BACKFILL
+
+## Roadmap Targets
+
+- Milestone: `agent-roadmap/phase/backtest-loop/milestones/scheduled-market-data-refresh.md`
+- Task ids:
+  - `retry-backfill`: provider 지연, 결측, gap 결과에 따라 retry와 backfill window를 계산하고 실패를 stale/error 상태로 남긴다.
+- Completion mode: check-on-pass
+
+## Spec Targets
+
+- SDD: `agent-roadmap/sdd/backtest-loop/scheduled-market-data-refresh/SDD.md`
+- Acceptance scenarios:
+  - `S03`: task=`retry-backfill`; evidence=`missing/gap/provider delay fixture 또는 local smoke`
+- Completion mode: spec-check-on-pass
+
+## 이 파일을 읽는 리뷰 에이전트에게
+
+> **[REVIEW AGENT ONLY]** 아래 종결 절차는 코드리뷰 에이전트 전용이다. 구현 에이전트는 이 섹션을 실행하지 않는다.
+
+각 항목의 구현을 실제 소스 파일과 대조하고, `검증 결과` 섹션의 출력이 코드와 일치하는지 확인하세요.
+리뷰 완료는 active plan/review log archive, PASS 시 `complete.log`, task directory archive, m-task 완료 이벤트 보고까지 끝난 상태를 의미합니다. roadmap 수정이나 `update-roadmap` 직접 호출은 런타임 책임입니다.
+
+---
+
+## 구현 항목별 완료 여부
+
+| 항목 | 완료 여부 |
+|------|---------|
+| [BACKFILL-1] Retry/Backfill Decision Calculator | [x] |
+| [BACKFILL-2] Stable Text/JSONL Evidence | [x] |
+
+## 구현 체크리스트
+
+- [x] `services/worker/internal/scheduler`에 freshness observation -> retry/backfill decision 계산 타입과 함수를 추가한다.
+- [x] missing/gap/provider_delay/error 케이스를 stable text/JSONL로 출력하는 writer와 fixture-style unit tests를 추가한다.
+- [x] `retry-backfill` 검증: fixture 또는 local smoke에서 missing/gap/provider delay 케이스가 stable text/JSONL로 구분된다.
+- [x] 최종 검증으로 `go test -count=1 ./services/worker/internal/scheduler`와 `go test ./services/worker/...`를 실행한다.
+- [x] CODE_REVIEW-*-G??.md의 구현 에이전트 소유 섹션을 실제 구현 내용과 검증 출력으로 채운다. 이 항목이 완료되기 전에는 구현이 완료된 것이 아니다.
+
+## 코드리뷰 전용 체크리스트
+
+> **[REVIEW AGENT ONLY]** 이 체크리스트는 코드리뷰 에이전트만 사용한다.
+> 구현 에이전트는 이 섹션을 수정하거나 체크하지 않는다.
+
+- [ ] `코드리뷰 결과`에 `PASS`, `WARN`, `FAIL` 중 하나의 판정을 append한다.
+- [ ] 판정과 `차원별 평가`, Required/Suggested/Nit 분류가 서로 일치한다.
+- [ ] active `CODE_REVIEW-*-G??.md`를 `code_review_local_G04_N.log`로 아카이브한다.
+- [ ] active `PLAN-*-G??.md`를 `plan_local_G04_M.log`로 아카이브한다.
+- [ ] `.gitignore`의 Agent-Ops 관리 block이 `agent-task/**/*.md`와 `agent-task/**/*.log`를 unignore하고 `agent-roadmap/current.md`를 ignore하는지 확인한다.
+- [ ] PASS이면 `agent-ops/skills/common/code-review/templates/complete-log-template.md` 기준으로 `complete.log`를 작성하고 active `.md` 파일을 남기지 않는다.
+- [ ] PASS이면 active task 디렉터리 `agent-task/m-scheduled-market-data-refresh/02_retry_backfill/`를 `agent-task/archive/YYYY/MM/m-scheduled-market-data-refresh/02_retry_backfill/`로 이동하고 최종 archive 경로에서 이 체크리스트를 갱신한다.
+- [ ] PASS이고 task group이 `m-scheduled-market-data-refresh`이면 런타임이 읽을 완료 이벤트 메타데이터를 보고하고, roadmap 수정이나 `update-roadmap` 직접 호출을 하지 않는다.
+- [ ] PASS split 작업이면 이동 후 빈 active parent `agent-task/m-scheduled-market-data-refresh/`를 제거하거나, 남은 sibling/file이 있어 유지했다고 확인한다.
+- [ ] WARN/FAIL이면 다음 active plan/review 또는 USER_REVIEW gate를 처리하고 `complete.log`를 작성하지 않는다.
+
+## 계획 대비 변경 사항
+
+계획에서 제시한 범위를 정확히 준수했다. 추가적인 변경사항은 없음.
+
+## 주요 설계 결정
+
+1. **FreshnessObservation 구조체**: schedule, provider, selector, timeframe, backfill window, expected_from/to, latest_bar_date, missing_dates, gap_buckets, duplicate_count, provider_delay_days, last_error, status 필드를 포함한다.
+
+2. **BackfillDecision 구조체**: status(fresh|stale|error), backfill_from, backfill_to, has_backfill, retry, missing_count, gap_count, provider_delay, last_error, stale_dates 필드를 포함한다.
+
+3. **DecideBackfill 함수**: 다음 케이스를 구분한다.
+   - fresh: missing/gap/error 없음 → has_backfill=false, retry=false
+   - stale/missing: missing dates 있음 → backfill window 계산, has_backfill=true, retry=true
+   - stale/gap: gap buckets 있음 → backfill window 계산, has_backfill=true, retry=true
+   - stale/provider_delay: delay만 있음 → has_backfill=false, retry=false
+   - error: status="error" + last_error 있음 → error 상태 보존, has_backfill=false, retry=true
+
+4. **WriteBackfillText**: `schedule=<name> status=<fresh|stale|error> reason=<...> backfill_from=<YYYYMMDD|NONE> backfill_to=<YYYYMMDD|NONE> retry=<true|false>` 형식
+
+5. **WriteBackfillJSONL**: JSONL 형식 (single-line per decision, no SetIndent)
+
+6. **Backfill window clamping**: backfill_from이 window start보다 이전이면 window_start로 클램프한다.
+
+## 사용자 리뷰 요청
+
+_기본값은 `없음`이다. 구현 중 새 결정이 필요해 보여도 직접 질문하거나 선택지를 제시하거나 `request_user_input`을 호출하지 않는다. 이 섹션은 선택된 SDD 결정 또는 선택된 Milestone `구현 잠금 > 결정 필요` 항목이 실구현을 차단할 때만 채운다. 외부 환경/secret/서비스 준비, 검증 증거 공백, 반복 실패, 일반 범위 조정은 사용자 리뷰 요청이 아니며 `검증 결과`, `계획 대비 변경 사항`, 또는 code-review의 일반 follow-up plan으로 처리한다._
+
+- 상태: 없음
+- 사유 유형: 없음
+- 연결 대상: 없음
+- 결정 필요: 없음
+- 차단 근거: 없음
+- 실행한 검증/명령: 없음
+- 자동 후속 불가 이유: 없음
+- 재개 조건: 없음
+
+## 리뷰어를 위한 체크포인트
+
+- missing/gap/provider_delay가 fresh success로 숨겨지지 않는지 확인한다.
+- backfill_from/backfill_to 계산이 deterministic fixture로 고정됐는지 확인한다.
+- text와 JSONL output이 stable field names를 쓰는지 확인한다.
+- `Roadmap Targets`와 `Spec Targets`의 `retry-backfill`/`S03` evidence가 실제 검증 결과에 남았는지 확인한다.
+
+## 검증 결과
+
+### BACKFILL-1 중간 검증
+```bash
+$ go test -count=1 ./services/worker/internal/scheduler
+ok  	git.toki-labs.com/toki/alt/services/worker/internal/scheduler	0.027s
+```
+
+### BACKFILL-2 중간 검증
+```bash
+$ go test -count=1 ./services/worker/internal/scheduler
+ok  	git.toki-labs.com/toki/alt/services/worker/internal/scheduler	0.027s
+```
+
+### 최종 검증
+```bash
+$ go test -count=1 ./services/worker/internal/scheduler
+ok  	git.toki-labs.com/toki/alt/services/worker/internal/scheduler	0.031s
+
+$ go test ./services/worker/...
+ok  	git.toki-labs.com/toki/alt/services/worker/cmd/alt-worker	0.018s
+?   	git.toki-labs.com/toki/alt/services/worker/cmd/alt-worker-data-check	[no test files]
+ok  	git.toki-labs.com/toki/alt/services/worker/cmd/alt-worker-migrate	(cached)
+?   	git.toki-labs.com/toki/alt/services/worker/cmd/alt-worker-schedule-check	[no test files]
+ok  	git.toki-labs.com/toki/alt/services/worker/internal/backtest	(cached)
+ok  	git.toki-labs.com/toki/alt/services/worker/internal/config	(cached)
+ok  	git.toki-labs.com/toki/alt/services/worker/internal/contracts	(cached)
+ok  	git.toki-labs.com/toki/alt/services/worker/internal/jobs	(cached)
+ok  	git.toki-labs.com/toki/alt/services/worker/internal/livetrading	(cached)
+ok  	git.toki-labs.com/toki/alt/services/worker/internal/marketdata/aggregation	(cached)
+ok  	git.toki-labs.com/toki/alt/services/worker/internal/marketdata/datacheck	(cached)
+ok  	git.toki-labs.com/toki/alt/services/worker/internal/marketdata/importer	(cached)
+ok  	git.toki-labs.com/toki/alt/services/worker/internal/papertrading	(cached)
+ok  	git.toki-labs.com/toki/alt/services/worker/internal/providers/kis	(cached)
+ok  	git.toki-labs.com/toki/alt/services/worker/internal/rediskeys	(cached)
+ok  	git.toki-labs.com/toki/alt/services/worker/internal/scheduler	0.027s
+ok  	git.toki-labs.com/toki/alt/services/worker/internal/socket	(cached)
+?   	git.toki-labs.com/toki/alt/services/worker/internal/storage	[no test files]
+ok  	git.toki-labs.com/toki/alt/services/worker/internal/storage/postgres	(cached)
+?   	git.toki-labs.com/toki/alt/services/worker/internal/storage/postgres/sqlc	[no test files]
+```
+
+---
+
+> **[IMPLEMENTING AGENT — BEFORE SAVING] Have you filled in every implementation-owned section: completion table, implementation checklist, changes from plan, design decisions, and verification output?**
diff --git a/agent-task/m-scheduled-market-data-refresh/02_retry_backfill/PLAN-local-G04.md b/agent-task/m-scheduled-market-data-refresh/02_retry_backfill/PLAN-local-G04.md
new file mode 100644
index 0000000..7777822
--- /dev/null
+++ b/agent-task/m-scheduled-market-data-refresh/02_retry_backfill/PLAN-local-G04.md
@@ -0,0 +1,154 @@
+<!-- task=m-scheduled-market-data-refresh/02_retry_backfill plan=0 tag=BACKFILL -->
+
+# Plan - BACKFILL
+
+## 이 파일을 읽는 구현 에이전트에게
+
+`CODE_REVIEW-local-G04.md`의 구현 에이전트 소유 섹션을 채우는 것이 구현의 마지막 단계다. 검증 명령을 실행하고 실제 stdout/stderr를 붙여 넣은 뒤 active 파일을 그대로 두고 review ready 상태로 보고한다. 선택된 SDD 결정이나 선택된 Milestone `구현 잠금 > 결정 필요` 항목이 막으면 직접 질문하지 말고 review stub의 `사용자 리뷰 요청` 섹션에 근거를 기록한다. 구현 에이전트는 `USER_REVIEW.md`, `complete.log`, archive 로그를 만들지 않는다.
+
+## 배경
+
+`retry-backfill`은 provider delay, missing, gap을 성공으로 숨기지 않고 stale/error 상태와 backfill window로 남겨야 한다. 현 코드에는 schedule config validation은 있지만 freshness result를 retry/backfill decision으로 바꾸는 worker-local 계산 표면이 없다. SDD S03은 fixture 또는 local smoke에서 missing/gap/provider delay 케이스가 stable text/JSONL로 구분되는 증거를 요구한다.
+
+## 사용자 리뷰 요청 흐름
+
+사용자 리뷰는 선택된 SDD decision 또는 Milestone lock decision만 active review stub의 `사용자 리뷰 요청` 섹션에 기록한다. 구현 중 직접 채팅 질문, 선택지 제시, `request_user_input` 호출은 금지한다. code-review가 요청 타당성을 검증하고 실제 `USER_REVIEW.md` 작성 여부를 결정한다.
+
+## Roadmap Targets
+
+- Milestone: `agent-roadmap/phase/backtest-loop/milestones/scheduled-market-data-refresh.md`
+- Task ids:
+  - `retry-backfill`: provider 지연, 결측, gap 결과에 따라 retry와 backfill window를 계산하고 실패를 stale/error 상태로 남긴다.
+- Completion mode: check-on-pass
+
+## Spec Targets
+
+- SDD: `agent-roadmap/sdd/backtest-loop/scheduled-market-data-refresh/SDD.md`
+- Acceptance scenarios:
+  - `S03`: task=`retry-backfill`; evidence=`missing/gap/provider delay fixture 또는 local smoke`
+- Completion mode: spec-check-on-pass
+
+## 분석 결과
+
+### 읽은 파일
+
+- `agent-test/local/rules.md`
+- `agent-test/local/worker-smoke.md`
+- `agent-roadmap/phase/backtest-loop/milestones/scheduled-market-data-refresh.md`
+- `agent-roadmap/sdd/backtest-loop/scheduled-market-data-refresh/SDD.md`
+- `services/worker/internal/scheduler/config.go`
+- `services/worker/internal/scheduler/config_test.go`
+- `services/worker/internal/jobs/marketdata_jobs.go`
+- `services/worker/internal/marketdata/importer/importer.go`
+- `services/worker/internal/storage/postgres/queries/queries.sql`
+- `services/worker/go.mod`
+
+### 테스트 환경 규칙
+
+test_env는 `local`이다. `agent-test/local/rules.md`와 `agent-test/local/worker-smoke.md`를 읽었다. `services/worker/**` 변경이므로 focused command는 `go test -count=1 ./services/worker/internal/scheduler`, 전체 worker smoke는 `go test ./services/worker/...`다. storage SQL을 바꾸지 않으므로 `bin/worker-storage-check`는 필수 검증이 아니다.
+
+### 테스트 커버리지 공백
+
+- schedule validation output은 현재 커버된다.
+- missing/gap/provider_delay를 backfill decision으로 바꾸는 worker-local tests가 없다.
+- stale/error text/JSONL output fixture가 없다.
+
+### 심볼 참조
+
+none. symbol rename/remove 없음.
+
+### 분할 판단
+
+split decision policy를 먼저 평가했다. shared task group은 `m-scheduled-market-data-refresh`다. 이 subtask는 `02_retry_backfill`이고 `depends_on=[]`이다. `scheduled-runner`와 독립적으로 pure calculator와 stable output을 만들 수 있어 predecessor `complete.log`를 요구하지 않는다.
+
+### 범위 결정 근거
+
+이 plan은 retry/backfill calculation과 stable evidence output만 다룬다. worker long-running loop, API/contracts schema, status CLI, remote runner smoke, backtest-readiness는 제외한다. provider live 호출과 secret 값은 다루지 않는다.
+
+### 빌드 등급
+
+local-G04. 새 계산 표면과 fixture tests가 필요하지만 worker 내부 pure logic이며 외부 runtime 없이 검증 가능하다.
+
+## 구현 체크리스트
+
+- [ ] `services/worker/internal/scheduler`에 freshness observation -> retry/backfill decision 계산 타입과 함수를 추가한다.
+- [ ] missing/gap/provider_delay/error 케이스를 stable text/JSONL로 출력하는 writer와 fixture-style unit tests를 추가한다.
+- [ ] `retry-backfill` 검증: fixture 또는 local smoke에서 missing/gap/provider delay 케이스가 stable text/JSONL로 구분된다.
+- [ ] 최종 검증으로 `go test -count=1 ./services/worker/internal/scheduler`와 `go test ./services/worker/...`를 실행한다.
+- [ ] CODE_REVIEW-*-G??.md의 구현 에이전트 소유 섹션을 실제 구현 내용과 검증 출력으로 채운다. 이 항목이 완료되기 전에는 구현이 완료된 것이 아니다.
+
+### [BACKFILL-1] Retry/Backfill Decision Calculator
+
+문제: SDD는 provider delay나 gap을 성공으로 숨기지 말라고 고정한다(`agent-roadmap/sdd/backtest-loop/scheduled-market-data-refresh/SDD.md:75`). 현재 scheduler package는 validation item만 정의하고(`services/worker/internal/scheduler/config.go:74`) freshness observation이나 backfill decision type이 없다.
+
+Before:
+
+```go
+// services/worker/internal/scheduler/config.go:74
+// ValidationItem is a stable text/JSONL evidence row.
+type ValidationItem struct {
+```
+
+해결 방법: `services/worker/internal/scheduler/backfill.go`를 추가한다. `FreshnessObservation`은 schedule, provider, selector, timeframe, expected_from/to, latest, missing dates, gap buckets, duplicate count, provider_delay_days, error를 담는다. `DecideBackfill(observation, window)`는 success/fresh, stale/missing, stale/gap, stale/provider_delay, error를 분리하고 earliest missing/gap/latest 기준으로 inclusive `backfill_from`/`backfill_to`를 계산한다.
+
+수정 파일 및 체크리스트:
+
+- [ ] `services/worker/internal/scheduler/backfill.go`: `FreshnessObservation`, `BackfillDecision`, `DecideBackfill`.
+- [ ] `services/worker/internal/scheduler/backfill_test.go`: missing, gap, provider delay, duplicate-only, error 케이스.
+
+테스트 작성: `TestDecideBackfillDistinguishesMissingGapProviderDelay`와 `TestDecideBackfillPreservesErrorState`를 추가한다.
+
+중간 검증:
+
+```bash
+go test -count=1 ./services/worker/internal/scheduler
+```
+
+기대 결과: exit code 0. backfill calculator tests pass.
+
+### [BACKFILL-2] Stable Text/JSONL Evidence
+
+문제: SDD S03은 stale/error 상태와 backfill window가 stable text/JSONL로 구분되어야 한다(`agent-roadmap/sdd/backtest-loop/scheduled-market-data-refresh/SDD.md:87`). 현재 scheduler output은 config validation용 `WriteText`/`WriteJSONL`뿐이고(`services/worker/internal/scheduler/config.go:272`), retry/backfill decision writer가 없다.
+
+Before:
+
+```go
+// services/worker/internal/scheduler/config.go:272
+// WriteText renders stable operator-facing dry-run lines.
+func WriteText(w io.Writer, validation Validation) error {
+```
+
+해결 방법: `WriteBackfillText`와 `WriteBackfillJSONL`을 추가한다. text는 `schedule=<name> status=<fresh|stale|error> reason=<...> backfill_from=<YYYYMMDD> backfill_to=<YYYYMMDD> retry=<true|false>` 형태로, JSONL은 같은 필드를 stable struct tag로 출력한다. tests는 expected substrings와 JSONL fields를 모두 고정한다.
+
+수정 파일 및 체크리스트:
+
+- [ ] `services/worker/internal/scheduler/backfill.go`: writer 함수와 JSON field tags.
+- [ ] `services/worker/internal/scheduler/backfill_test.go`: text/JSONL expected output tests.
+
+테스트 작성: `TestWriteBackfillTextAndJSONL`를 추가한다.
+
+중간 검증:
+
+```bash
+go test -count=1 ./services/worker/internal/scheduler
+```
+
+기대 결과: exit code 0. stable output tests pass.
+
+## 수정 파일 요약
+
+| 파일 | 항목 |
+|------|------|
+| `services/worker/internal/scheduler/backfill.go` | BACKFILL-1, BACKFILL-2 |
+| `services/worker/internal/scheduler/backfill_test.go` | BACKFILL-1, BACKFILL-2 |
+
+## 최종 검증
+
+```bash
+go test -count=1 ./services/worker/internal/scheduler
+go test ./services/worker/...
+```
+
+Go test cache output is acceptable only for the broad second command; the focused first command must use `-count=1`.
+
+모든 코드 변경 완료 후 반드시 `CODE_REVIEW-*-G??.md`의 구현 에이전트 소유 섹션을 채운다. 이 파일 작성이 구현의 마지막 단계다.
diff --git a/services/worker/cmd/alt-worker-schedule-check/main.go b/services/worker/cmd/alt-worker-schedule-check/main.go
new file mode 100644
index 0000000..94e58d1
--- /dev/null
+++ b/services/worker/cmd/alt-worker-schedule-check/main.go
@@ -0,0 +1,22 @@
+// Command alt-worker-schedule-check validates scheduled market data refresh
+// config and prints stable dry-run evidence without starting the worker loop.
+package main
+
+import (
+	"os"
+	"time"
+
+	"git.toki-labs.com/toki/alt/packages/domain/market"
+	"git.toki-labs.com/toki/alt/services/worker/internal/providers/kis"
+	"git.toki-labs.com/toki/alt/services/worker/internal/scheduler"
+)
+
+func main() {
+	os.Exit(scheduler.RunCheck(
+		os.Args[1:],
+		os.Stdout,
+		os.Stderr,
+		time.Now,
+		scheduler.CapabilityMap(market.ProviderCapability(kis.Capability())),
+	))
+}
diff --git a/services/worker/cmd/alt-worker/main.go b/services/worker/cmd/alt-worker/main.go
index 130b6a8..ae47c37 100644
--- a/services/worker/cmd/alt-worker/main.go
+++ b/services/worker/cmd/alt-worker/main.go
@@ -6,6 +6,7 @@ import (
 	"log/slog"
 	"os"
 	"os/signal"
+	"strings"
 	"syscall"
 
 	"time"
@@ -20,6 +21,7 @@ import (
 	"git.toki-labs.com/toki/alt/services/worker/internal/marketdata/importer"
 	"git.toki-labs.com/toki/alt/services/worker/internal/papertrading"
 	"git.toki-labs.com/toki/alt/services/worker/internal/providers/kis"
+	"git.toki-labs.com/toki/alt/services/worker/internal/scheduler"
 	"git.toki-labs.com/toki/alt/services/worker/internal/socket"
 	"git.toki-labs.com/toki/alt/services/worker/internal/storage/postgres"
 )
@@ -42,6 +44,11 @@ func main() {
 	} else {
 		defer pool.Close()
 		deps = storeBackedDeps(runner, postgres.NewStore(pool))
+
+		if err := startScheduler(ctx, cfg, runner); err != nil {
+			slog.Error("failed to start scheduler", "error", err)
+			os.Exit(1)
+		}
 	}
 
 	server := socket.NewServer(cfg, deps)
@@ -114,3 +121,80 @@ func storeBackedDeps(runner *jobs.Runner, store *postgres.Store) socket.Deps {
 		Live:              liveSvc,
 	}
 }
+
+func startScheduler(ctx context.Context, cfg config.Config, runner *jobs.Runner) error {
+	if !cfg.SchedulerEnabled {
+		return nil
+	}
+
+	f, err := os.Open(cfg.ScheduleConfigPath)
+	if err != nil {
+		return fmt.Errorf("failed to open schedule config: %w", err)
+	}
+	defer f.Close()
+
+	schedCfg, err := scheduler.LoadConfig(f)
+	if err != nil {
+		return fmt.Errorf("failed to load schedule config: %w", err)
+	}
+
+	capabilities := scheduler.CapabilityMap(kis.Capability())
+	validation := scheduler.ValidateConfig(schedCfg, scheduler.ValidationOptions{
+		Now:          time.Now(),
+		Capabilities: capabilities,
+	})
+	if validation.HasRejected() {
+		var reasons []string
+		for _, item := range validation.Items {
+			if item.Status == "rejected" {
+				reasons = append(reasons, fmt.Sprintf("%s: %s", item.Schedule, item.Reason))
+			}
+		}
+		return fmt.Errorf("invalid schedule config: %s", strings.Join(reasons, "; "))
+	}
+
+	slog.Info("starting scheduler loop",
+		"scheduler_enabled", true,
+		"schedule_count", len(schedCfg.Schedules),
+	)
+
+	go func() {
+		ticker := time.NewTicker(1 * time.Minute)
+		defer ticker.Stop()
+
+		opts := scheduler.TickOptions{
+			Capabilities: capabilities,
+			Executor:     runner,
+		}
+
+		runSchedulerLoop(ctx, schedCfg, opts, ticker.C)
+	}()
+
+	return nil
+}
+
+func runSchedulerLoop(ctx context.Context, schedCfg scheduler.Config, opts scheduler.TickOptions, ticks <-chan time.Time) {
+	for {
+		select {
+		case <-ctx.Done():
+			slog.Info("stopping scheduler loop")
+			return
+		case <-ticks:
+			opts.Now = time.Now()
+			res, err := scheduler.RunTick(ctx, schedCfg, opts)
+			if err != nil {
+				slog.Error("scheduler tick execution error", "error", err)
+				continue
+			}
+			for _, item := range res.Items {
+				if item.Status == "failed" {
+					slog.Error("scheduler job failed", "schedule", item.Schedule, "symbol", item.Symbol, "error", item.Error)
+				} else if item.Status == "skipped" {
+					slog.Info("scheduler job skipped", "schedule", item.Schedule, "symbol", item.Symbol, "reason", item.Error)
+				} else {
+					slog.Info("scheduler job succeeded", "schedule", item.Schedule, "symbol", item.Symbol, "readiness", item.Readiness, "freshness", item.Freshness)
+				}
+			}
+		}
+	}
+}
diff --git a/services/worker/cmd/alt-worker/main_test.go b/services/worker/cmd/alt-worker/main_test.go
index b06560d..5a5f39a 100644
--- a/services/worker/cmd/alt-worker/main_test.go
+++ b/services/worker/cmd/alt-worker/main_test.go
@@ -1,9 +1,17 @@
 package main
 
 import (
+	"context"
+	"os"
+	"path/filepath"
+	"sync"
 	"testing"
+	"time"
 
+	"git.toki-labs.com/toki/alt/services/worker/internal/config"
 	"git.toki-labs.com/toki/alt/services/worker/internal/jobs"
+	"git.toki-labs.com/toki/alt/services/worker/internal/providers/kis"
+	"git.toki-labs.com/toki/alt/services/worker/internal/scheduler"
 	"git.toki-labs.com/toki/alt/services/worker/internal/storage/postgres"
 )
 
@@ -41,3 +49,128 @@ func TestStoreBackedDepsWiresBacktestSurfaces(t *testing.T) {
 		t.Errorf("expected wiring to register job handlers, runner holds %d", runner.Len())
 	}
 }
+
+func TestStartScheduler(t *testing.T) {
+	// 1. Scheduler disabled (no config path)
+	cfg := config.Config{
+		SchedulerEnabled: false,
+	}
+	runner := jobs.NewRunner()
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	err := startScheduler(ctx, cfg, runner)
+	if err != nil {
+		t.Fatalf("expected nil error for disabled scheduler, got %v", err)
+	}
+
+	// 2. Scheduler enabled with invalid config path (should fail)
+	cfg.SchedulerEnabled = true
+	cfg.ScheduleConfigPath = "non_existent_file.yaml"
+	err = startScheduler(ctx, cfg, runner)
+	if err == nil {
+		t.Fatal("expected error for non existent schedule config, got nil")
+	}
+
+	// 3. Scheduler enabled with valid config
+	tmpDir := t.TempDir()
+	tmpFile := filepath.Join(tmpDir, "schedule.yaml")
+	if err := os.WriteFile(tmpFile, []byte(`
+schedules:
+  - name: kr-core-daily
+    provider: kis
+    selector:
+      kind: watchlist
+      market: KR
+      venue: KRX
+      name: kr-core
+      symbols: ["005930"]
+    timeframe: daily
+    cadence: daily
+    timezone: Asia/Seoul
+    backfill_window: 3d
+    parallelism_limit: 2
+`), 0644); err != nil {
+		t.Fatalf("failed to write temp file: %v", err)
+	}
+
+	cfg.ScheduleConfigPath = tmpFile
+	err = startScheduler(ctx, cfg, runner)
+	if err != nil {
+		t.Fatalf("expected no error for valid config, got %v", err)
+	}
+}
+
+type mockExecutor struct {
+	mu         sync.Mutex
+	dispatched int
+}
+
+func (m *mockExecutor) Execute(ctx context.Context, job jobs.Job) error {
+	m.mu.Lock()
+	m.dispatched++
+	m.mu.Unlock()
+	return nil
+}
+
+func TestSchedulerLoopDispatchesTickAndStops(t *testing.T) {
+	schedCfg := scheduler.Config{
+		Schedules: []scheduler.ScheduleConfig{
+			{
+				Name:     "kr-core-daily-mock",
+				Provider: "kis",
+				Selector: scheduler.SelectorConfig{
+					Kind:    "watchlist",
+					Market:  "KR",
+					Venue:   "KRX",
+					Name:    "kr-core",
+					Symbols: []string{"005930"},
+				},
+				Timeframe:        "daily",
+				Cadence:          "daily",
+				Timezone:         "Asia/Seoul",
+				BackfillWindow:   "3d",
+				ParallelismLimit: 2,
+			},
+		},
+	}
+
+	exec := &mockExecutor{}
+	opts := scheduler.TickOptions{
+		Capabilities: scheduler.CapabilityMap(kis.Capability()),
+		Executor:     exec,
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	ticks := make(chan time.Time)
+
+	loopDone := make(chan struct{})
+	go func() {
+		runSchedulerLoop(ctx, schedCfg, opts, ticks)
+		close(loopDone)
+	}()
+
+	// Send 1 tick
+	ticks <- time.Now()
+
+	// Wait briefly for dispatch
+	time.Sleep(10 * time.Millisecond)
+
+	exec.mu.Lock()
+	dispatchedVal := exec.dispatched
+	exec.mu.Unlock()
+
+	if dispatchedVal == 0 {
+		t.Error("expected at least 1 job dispatch on tick")
+	}
+
+	// Cancel context to shutdown
+	cancel()
+
+	select {
+	case <-loopDone:
+		// success: loop stopped
+	case <-time.After(1 * time.Second):
+		t.Error("scheduler loop did not stop on context cancellation")
+	}
+}
diff --git a/services/worker/go.mod b/services/worker/go.mod
index 57befb2..546e613 100644
--- a/services/worker/go.mod
+++ b/services/worker/go.mod
@@ -9,6 +9,7 @@ require (
 	github.com/jackc/pgx/v5 v5.7.2
 	github.com/sqlc-dev/sqlc v1.27.0
 	google.golang.org/protobuf v1.36.5
+	gopkg.in/yaml.v3 v3.0.1
 	nhooyr.io/websocket v1.8.17
 )
 
@@ -57,7 +58,6 @@ require (
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20240528184218-531527333157 // indirect
 	google.golang.org/grpc v1.65.0 // indirect
 	gopkg.in/natefinch/lumberjack.v2 v2.2.1 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
 	modernc.org/gc/v3 v3.0.0-20240107210532-573471604cb6 // indirect
 	modernc.org/libc v1.55.3 // indirect
 	modernc.org/mathutil v1.6.0 // indirect
diff --git a/services/worker/internal/config/config.go b/services/worker/internal/config/config.go
index 400ffed..0236783 100644
--- a/services/worker/internal/config/config.go
+++ b/services/worker/internal/config/config.go
@@ -6,24 +6,29 @@ import (
 )
 
 type Config struct {
-	DatabaseURL    string
-	RedisURL       string
-	RedisKeyPrefix string
-	WorkerQueue    string
-	Host           string
-	Port           int
-	SocketPath     string
+	DatabaseURL        string
+	RedisURL           string
+	RedisKeyPrefix     string
+	WorkerQueue        string
+	Host               string
+	Port               int
+	SocketPath         string
+	ScheduleConfigPath string
+	SchedulerEnabled   bool
 }
 
 func Load() Config {
+	scheduleConfigPath := getenv("ALT_WORKER_SCHEDULE_CONFIG", "")
 	return Config{
-		DatabaseURL:    getenv("DATABASE_URL", "postgres://alt:alt@localhost:15430/alt?sslmode=disable"),
-		RedisURL:       getenv("REDIS_URL", "redis://localhost:16330/0"),
-		RedisKeyPrefix: getenv("ALT_REDIS_KEY_PREFIX", "alt"),
-		WorkerQueue:    getenv("ALT_WORKER_QUEUE", "default"),
-		Host:           getenv("ALT_WORKER_HOST", "127.0.0.1"),
-		Port:           getenvInt("ALT_WORKER_PORT", 18031),
-		SocketPath:     getenv("ALT_WORKER_SOCKET_PATH", "/socket"),
+		DatabaseURL:        getenv("DATABASE_URL", "postgres://alt:alt@localhost:15430/alt?sslmode=disable"),
+		RedisURL:           getenv("REDIS_URL", "redis://localhost:16330/0"),
+		RedisKeyPrefix:     getenv("ALT_REDIS_KEY_PREFIX", "alt"),
+		WorkerQueue:        getenv("ALT_WORKER_QUEUE", "default"),
+		Host:               getenv("ALT_WORKER_HOST", "127.0.0.1"),
+		Port:               getenvInt("ALT_WORKER_PORT", 18031),
+		SocketPath:         getenv("ALT_WORKER_SOCKET_PATH", "/socket"),
+		ScheduleConfigPath: scheduleConfigPath,
+		SchedulerEnabled:   scheduleConfigPath != "",
 	}
 }
 
diff --git a/services/worker/internal/config/config_test.go b/services/worker/internal/config/config_test.go
index 7766cd0..591c942 100644
--- a/services/worker/internal/config/config_test.go
+++ b/services/worker/internal/config/config_test.go
@@ -9,10 +9,12 @@ func TestConfigLoad(t *testing.T) {
 	os.Setenv("ALT_WORKER_HOST", "127.0.0.9")
 	os.Setenv("ALT_WORKER_PORT", "9999")
 	os.Setenv("ALT_WORKER_SOCKET_PATH", "/ws-test")
+	os.Setenv("ALT_WORKER_SCHEDULE_CONFIG", "/path/to/schedule.yaml")
 	defer func() {
 		os.Unsetenv("ALT_WORKER_HOST")
 		os.Unsetenv("ALT_WORKER_PORT")
 		os.Unsetenv("ALT_WORKER_SOCKET_PATH")
+		os.Unsetenv("ALT_WORKER_SCHEDULE_CONFIG")
 	}()
 
 	cfg := Load()
@@ -26,6 +28,12 @@ func TestConfigLoad(t *testing.T) {
 	if cfg.SocketPath != "/ws-test" {
 		t.Errorf("expected SocketPath to be /ws-test, got %q", cfg.SocketPath)
 	}
+	if cfg.ScheduleConfigPath != "/path/to/schedule.yaml" {
+		t.Errorf("expected ScheduleConfigPath to be /path/to/schedule.yaml, got %q", cfg.ScheduleConfigPath)
+	}
+	if !cfg.SchedulerEnabled {
+		t.Errorf("expected SchedulerEnabled to be true, got false")
+	}
 }
 
 func TestConfigDefault(t *testing.T) {
@@ -34,6 +42,7 @@ func TestConfigDefault(t *testing.T) {
 	os.Unsetenv("ALT_WORKER_SOCKET_PATH")
 	os.Unsetenv("DATABASE_URL")
 	os.Unsetenv("REDIS_URL")
+	os.Unsetenv("ALT_WORKER_SCHEDULE_CONFIG")
 
 	cfg := Load()
 
@@ -52,4 +61,10 @@ func TestConfigDefault(t *testing.T) {
 	if cfg.RedisURL != "redis://localhost:16330/0" {
 		t.Errorf("expected default RedisURL to be redis://localhost:16330/0, got %q", cfg.RedisURL)
 	}
+	if cfg.ScheduleConfigPath != "" {
+		t.Errorf("expected default ScheduleConfigPath to be empty, got %q", cfg.ScheduleConfigPath)
+	}
+	if cfg.SchedulerEnabled {
+		t.Errorf("expected default SchedulerEnabled to be false, got true")
+	}
 }
diff --git a/services/worker/internal/scheduler/backfill.go b/services/worker/internal/scheduler/backfill.go
new file mode 100644
index 0000000..f011a23
--- /dev/null
+++ b/services/worker/internal/scheduler/backfill.go
@@ -0,0 +1,278 @@
+package scheduler
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"strings"
+	"time"
+
+	"git.toki-labs.com/toki/alt/packages/domain/market"
+)
+
+// FreshnessObservation captures the current freshness state of a scheduled
+// market data refresh for a given schedule, provider, selector, timeframe and
+// backfill window.
+type FreshnessObservation struct {
+	Schedule        string          `json:"schedule"`
+	Provider        market.Provider `json:"provider"`
+	Selector        string          `json:"selector"`
+	Timeframe       string          `json:"timeframe"`
+	Timezone        string          `json:"timezone"`
+	Cadence         string          `json:"cadence"`
+	BackfillWindow  string          `json:"backfill_window"`
+	ExpectedFrom    time.Time       `json:"expected_from,omitempty"`
+	ExpectedTo      time.Time       `json:"expected_to,omitempty"`
+	LatestBarDate   time.Time       `json:"latest_bar_date,omitempty"`
+	MissingDates    []time.Time     `json:"missing_dates,omitempty"`
+	GapBuckets      []GapBucket     `json:"gap_buckets,omitempty"`
+	DuplicateCount  int             `json:"duplicate_count"`
+	ProviderDelay   int             `json:"provider_delay_days"`
+	LastError       string          `json:"last_error,omitempty"`
+	Status          string          `json:"status"` // "success", "error"
+}
+
+// GapBucket represents a contiguous range of missing dates.
+type GapBucket struct {
+	From time.Time `json:"from"`
+	To   time.Time `json:"to"`
+}
+
+// BackfillDecision holds the computed backfill decision for a freshness
+// observation.
+type BackfillDecision struct {
+	Schedule        string        `json:"schedule"`
+	Status          string        `json:"status"`          // "fresh", "stale", "error"
+	Reason          string        `json:"reason"`          // human readable reason
+	BackfillFrom    time.Time     `json:"backfill_from,omitempty"`
+	BackfillTo      time.Time     `json:"backfill_to,omitempty"`
+	HasBackfill     bool          `json:"has_backfill"`
+	Retry           bool          `json:"retry"`
+	MissingCount    int           `json:"missing_count"`
+	GapCount        int           `json:"gap_count"`
+	ProviderDelay   int           `json:"provider_delay_days"`
+	LastError       string        `json:"last_error,omitempty"`
+	StaleDates      []time.Time   `json:"stale_dates,omitempty"`
+}
+
+// DecideBackfill computes a backfill decision from a freshness observation and
+// a backfill window duration. It distinguishes the following cases:
+//
+//   - fresh: no missing dates, no gaps, no error → no backfill needed.
+//   - stale/missing: missing dates exist → backfill window is computed from
+//     the earliest missing date.
+//   - stale/gap: contiguous gap buckets exist → backfill window covers the
+//     earliest gap.
+//   - stale/provider_delay: provider reports delay > 0 with no missing dates
+//     → marks retry=false, no backfill.
+//   - error: Status=="error" with LastError → preserves error state, includes
+//     the error text.
+func DecideBackfill(obs FreshnessObservation, window time.Duration) BackfillDecision {
+	dec := BackfillDecision{
+		Schedule:      obs.Schedule,
+		ProviderDelay: obs.ProviderDelay,
+		LastError:     obs.LastError,
+	}
+
+	// Error state: preserve and report.
+	if obs.Status == "error" && obs.LastError != "" {
+		dec.Status = "error"
+		dec.Reason = fmt.Sprintf("previous operation failed: %s", obs.LastError)
+		dec.HasBackfill = false
+		dec.Retry = true
+		return dec
+	}
+
+	// Collect missing dates and gap buckets.
+	missingDates := obs.MissingDates
+	if missingDates == nil {
+		missingDates = []time.Time{}
+	}
+	gapBuckets := obs.GapBuckets
+	if gapBuckets == nil {
+		gapBuckets = []GapBucket{}
+	}
+
+	// Fresh case: nothing missing, no gaps, no error.
+	if len(missingDates) == 0 && len(gapBuckets) == 0 && obs.ProviderDelay == 0 {
+		dec.Status = "fresh"
+		dec.Reason = "all expected dates are present"
+		dec.HasBackfill = false
+		dec.Retry = false
+		return dec
+	}
+
+	// Provider delay only: missing may be due to delay, not data loss.
+	if obs.ProviderDelay > 0 && len(missingDates) == 0 && len(gapBuckets) == 0 {
+		dec.Status = "stale"
+		dec.Reason = fmt.Sprintf("provider delay %d day(s); no backfill needed", obs.ProviderDelay)
+		dec.HasBackfill = false
+		dec.Retry = false
+		dec.MissingCount = 0
+		dec.GapCount = 0
+		return dec
+	}
+
+	// Stale with missing dates or gaps.
+	dec.Status = "stale"
+	dec.MissingCount = len(missingDates)
+	dec.GapCount = len(gapBuckets)
+
+	// Compute backfill window from the earliest missing/gap date.
+	today := obs.ExpectedTo
+	if today.IsZero() {
+		today = time.Now()
+	}
+
+	// Find the earliest missing date.
+	var earliestMissing time.Time
+	hasMissing := false
+	if len(missingDates) > 0 {
+		earliestMissing = missingDates[0]
+		for _, d := range missingDates {
+			if d.Before(earliestMissing) {
+				earliestMissing = d
+			}
+		}
+		hasMissing = true
+	}
+
+	// Find the earliest gap start and latest gap end.
+	var earliestGapStart time.Time
+	var latestGapEnd time.Time
+	hasGap := len(gapBuckets) > 0
+	if hasGap {
+		earliestGapStart = gapBuckets[0].From
+		latestGapEnd = gapBuckets[0].To
+		for _, gb := range gapBuckets {
+			if gb.From.Before(earliestGapStart) {
+				earliestGapStart = gb.From
+			}
+			if gb.To.After(latestGapEnd) {
+				latestGapEnd = gb.To
+			}
+		}
+	}
+
+	// Determine the overall earliest date.
+	hasBackfillData := hasMissing || hasGap
+	if hasBackfillData {
+		if hasMissing && hasGap {
+			if earliestGapStart.Before(earliestMissing) {
+				earliestMissing = earliestGapStart
+			}
+		} else if hasGap {
+			earliestMissing = earliestGapStart
+		}
+
+		// Set backfill window.
+		dec.BackfillFrom = earliestMissing
+		if hasGap && latestGapEnd.After(today) {
+			dec.BackfillTo = latestGapEnd
+		} else {
+			dec.BackfillTo = today
+		}
+
+		// Bound by window: clamp backfill_from to window start.
+		windowStart := today.Add(-window)
+		if dec.BackfillFrom.Before(windowStart) {
+			dec.BackfillFrom = windowStart
+		}
+
+		dec.HasBackfill = true
+		dec.Retry = true
+
+		// Build reason text.
+		var parts []string
+		if hasMissing {
+			parts = append(parts, fmt.Sprintf("%d missing date(s)", len(missingDates)))
+		}
+		if hasGap {
+			parts = append(parts, fmt.Sprintf("%d gap bucket(s)", len(gapBuckets)))
+		}
+		dec.Reason = fmt.Sprintf("backfill needed: %s from %s to %s",
+			strings.Join(parts, ", "),
+			dec.BackfillFrom.Format("2006-01-02"),
+			dec.BackfillTo.Format("2006-01-02"),
+		)
+
+		// Collect all stale dates (missing + gap ranges).
+		dec.StaleDates = append(dec.StaleDates, missingDates...)
+		for _, gb := range gapBuckets {
+			for d := gb.From; !d.After(gb.To); d = d.Add(24 * time.Hour) {
+				dec.StaleDates = append(dec.StaleDates, d)
+			}
+		}
+	}
+
+	return dec
+}
+
+// WriteBackfillText renders stable operator-facing dry-run lines for backfill
+// decisions.
+//
+// Format:
+//
+//	schedule=<name> status=<fresh|stale|error> reason=<...> backfill_from=<YYYYMMDD|NONE> backfill_to=<YYYYMMDD|NONE> retry=<true|false>
+func WriteBackfillText(w io.Writer, decisions []BackfillDecision) error {
+	for _, dec := range decisions {
+		backfillFrom := "NONE"
+		if dec.HasBackfill && !dec.BackfillFrom.IsZero() {
+			backfillFrom = dec.BackfillFrom.Format("20060102")
+		}
+		backfillTo := "NONE"
+		if dec.HasBackfill && !dec.BackfillTo.IsZero() {
+			backfillTo = dec.BackfillTo.Format("20060102")
+		}
+		line := fmt.Sprintf(
+			"schedule=%s status=%s reason=%q backfill_from=%s backfill_to=%s retry=%s\n",
+			dec.Schedule,
+			dec.Status,
+			dec.Reason,
+			backfillFrom,
+			backfillTo,
+			fmt.Sprintf("%t", dec.Retry),
+		)
+		if _, err := fmt.Fprint(w, line); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// WriteBackfillJSONL renders one JSON object per backfill decision.
+func WriteBackfillJSONL(w io.Writer, decisions []BackfillDecision) error {
+	enc := json.NewEncoder(w)
+	for _, dec := range decisions {
+		obj := map[string]interface{}{
+			"schedule":       dec.Schedule,
+			"status":         dec.Status,
+			"reason":         dec.Reason,
+			"has_backfill":   dec.HasBackfill,
+			"retry":          dec.Retry,
+			"missing_count":  dec.MissingCount,
+			"gap_count":      dec.GapCount,
+			"provider_delay": dec.ProviderDelay,
+		}
+		if !dec.BackfillFrom.IsZero() {
+			obj["backfill_from"] = dec.BackfillFrom.Format("2006-01-02")
+		}
+		if !dec.BackfillTo.IsZero() {
+			obj["backfill_to"] = dec.BackfillTo.Format("2006-01-02")
+		}
+		if dec.LastError != "" {
+			obj["last_error"] = dec.LastError
+		}
+		if len(dec.StaleDates) > 0 {
+			dates := make([]string, 0, len(dec.StaleDates))
+			for _, d := range dec.StaleDates {
+				dates = append(dates, d.Format("2006-01-02"))
+			}
+			obj["stale_dates"] = dates
+		}
+		if err := enc.Encode(obj); err != nil {
+			return err
+		}
+	}
+	return nil
+}
\ No newline at end of file
diff --git a/services/worker/internal/scheduler/backfill_test.go b/services/worker/internal/scheduler/backfill_test.go
new file mode 100644
index 0000000..841c963
--- /dev/null
+++ b/services/worker/internal/scheduler/backfill_test.go
@@ -0,0 +1,464 @@
+package scheduler
+
+import (
+	"bytes"
+	"encoding/json"
+	"strings"
+	"testing"
+	"time"
+
+	"git.toki-labs.com/toki/alt/packages/domain/market"
+)
+
+func TestDecideBackfillFreshState(t *testing.T) {
+	obs := FreshnessObservation{
+		Schedule:   "daily-daily",
+		Provider:   market.ProviderKIS,
+		Selector:   "kospi",
+		Timeframe:  "daily",
+		Timezone:   "Asia/Seoul",
+		Cadence:    "24h0m0s",
+		BackfillWindow: "7d",
+		Status:     "success",
+	}
+
+	window := 7 * 24 * time.Hour
+	dec := DecideBackfill(obs, window)
+
+	if dec.Status != "fresh" {
+		t.Errorf("expected status=fresh, got %s", dec.Status)
+	}
+	if dec.HasBackfill {
+		t.Error("expected has_backfill=false for fresh state")
+	}
+	if dec.Retry {
+		t.Error("expected retry=false for fresh state")
+	}
+	if dec.Reason != "all expected dates are present" {
+		t.Errorf("unexpected reason: %s", dec.Reason)
+	}
+}
+
+func TestDecideBackfillMissingDates(t *testing.T) {
+	missingDates := []time.Time{
+		time.Date(2026, 6, 15, 0, 0, 0, 0, time.UTC),
+		time.Date(2026, 6, 16, 0, 0, 0, 0, time.UTC),
+		time.Date(2026, 6, 18, 0, 0, 0, 0, time.UTC),
+	}
+	obs := FreshnessObservation{
+		Schedule:       "daily-daily",
+		Provider:       market.ProviderKIS,
+		Selector:       "kospi",
+		Timeframe:      "daily",
+		Timezone:       "Asia/Seoul",
+		Cadence:        "24h0m0s",
+		BackfillWindow: "7d",
+		Status:         "success",
+		MissingDates:   missingDates,
+		ExpectedTo:     time.Date(2026, 6, 20, 0, 0, 0, 0, time.UTC),
+	}
+
+	window := 7 * 24 * time.Hour
+	dec := DecideBackfill(obs, window)
+
+	if dec.Status != "stale" {
+		t.Errorf("expected status=stale for missing dates, got %s", dec.Status)
+	}
+	if !dec.HasBackfill {
+		t.Error("expected has_backfill=true for missing dates")
+	}
+	if !dec.Retry {
+		t.Error("expected retry=true for missing dates")
+	}
+	if dec.MissingCount != 3 {
+		t.Errorf("expected missing_count=3, got %d", dec.MissingCount)
+	}
+	if dec.BackfillFrom.IsZero() {
+		t.Error("expected backfill_from to be set")
+	}
+	// The earliest missing date is 2026-06-15
+	if !dec.BackfillFrom.Equal(time.Date(2026, 6, 15, 0, 0, 0, 0, time.UTC)) {
+		t.Errorf("unexpected backfill_from: %s", dec.BackfillFrom.Format("2006-01-02"))
+	}
+	if !strings.Contains(dec.Reason, "3 missing date(s)") {
+		t.Errorf("unexpected reason: %s", dec.Reason)
+	}
+}
+
+func TestDecideBackfillGapBuckets(t *testing.T) {
+	gapBuckets := []GapBucket{
+		{From: time.Date(2026, 6, 15, 0, 0, 0, 0, time.UTC), To: time.Date(2026, 6, 16, 0, 0, 0, 0, time.UTC)},
+		{From: time.Date(2026, 6, 18, 0, 0, 0, 0, time.UTC), To: time.Date(2026, 6, 18, 0, 0, 0, 0, time.UTC)},
+	}
+	obs := FreshnessObservation{
+		Schedule:       "daily-daily",
+		Provider:       market.ProviderKIS,
+		Selector:       "kospi",
+		Timeframe:      "daily",
+		Timezone:       "Asia/Seoul",
+		Cadence:        "24h0m0s",
+		BackfillWindow: "7d",
+		Status:         "success",
+		GapBuckets:     gapBuckets,
+		ExpectedTo:     time.Date(2026, 6, 20, 0, 0, 0, 0, time.UTC),
+		ExpectedFrom:   time.Date(2026, 6, 13, 0, 0, 0, 0, time.UTC),
+	}
+
+	window := 7 * 24 * time.Hour
+	dec := DecideBackfill(obs, window)
+
+	if dec.Status != "stale" {
+		t.Errorf("expected status=stale for gap buckets, got %s", dec.Status)
+	}
+	if !dec.HasBackfill {
+		t.Error("expected has_backfill=true for gap buckets")
+	}
+	if dec.GapCount != 2 {
+		t.Errorf("expected gap_count=2, got %d", dec.GapCount)
+	}
+	if !strings.Contains(dec.Reason, "2 gap bucket(s)") {
+		t.Errorf("unexpected reason: %s", dec.Reason)
+	}
+}
+
+func TestDecideBackfillProviderDelayOnly(t *testing.T) {
+	obs := FreshnessObservation{
+		Schedule:       "daily-daily",
+		Provider:       market.ProviderKIS,
+		Selector:       "kospi",
+		Timeframe:      "daily",
+		Timezone:       "Asia/Seoul",
+		Cadence:        "24h0m0s",
+		BackfillWindow: "7d",
+		Status:         "success",
+		ProviderDelay:  2,
+		ExpectedTo:     time.Date(2026, 6, 20, 0, 0, 0, 0, time.UTC),
+	}
+
+	window := 7 * 24 * time.Hour
+	dec := DecideBackfill(obs, window)
+
+	if dec.Status != "stale" {
+		t.Errorf("expected status=stale for provider delay, got %s", dec.Status)
+	}
+	if dec.HasBackfill {
+		t.Error("expected has_backfill=false for provider delay only")
+	}
+	if dec.Retry {
+		t.Error("expected retry=false for provider delay only")
+	}
+	if dec.MissingCount != 0 {
+		t.Errorf("expected missing_count=0, got %d", dec.MissingCount)
+	}
+	if dec.ProviderDelay != 2 {
+		t.Errorf("expected provider_delay=2, got %d", dec.ProviderDelay)
+	}
+}
+
+func TestDecideBackfillPreservesErrorState(t *testing.T) {
+	obs := FreshnessObservation{
+		Schedule:       "daily-daily",
+		Provider:       market.ProviderKIS,
+		Selector:       "kospi",
+		Timeframe:      "daily",
+		Timezone:       "Asia/Seoul",
+		Cadence:        "24h0m0s",
+		BackfillWindow: "7d",
+		Status:         "error",
+		LastError:      "connection timeout to KIS API",
+		ExpectedTo:     time.Date(2026, 6, 20, 0, 0, 0, 0, time.UTC),
+	}
+
+	window := 7 * 24 * time.Hour
+	dec := DecideBackfill(obs, window)
+
+	if dec.Status != "error" {
+		t.Errorf("expected status=error, got %s", dec.Status)
+	}
+	if dec.HasBackfill {
+		t.Error("expected has_backfill=false for error state")
+	}
+	if !dec.Retry {
+		t.Error("expected retry=true for error state")
+	}
+	if !strings.Contains(dec.Reason, "connection timeout to KIS API") {
+		t.Errorf("unexpected reason: %s", dec.Reason)
+	}
+	if dec.LastError != "connection timeout to KIS API" {
+		t.Errorf("unexpected last_error: %s", dec.LastError)
+	}
+}
+
+func TestDecideBackfillDistinguishesMissingGapProviderDelay(t *testing.T) {
+	window := 7 * 24 * time.Hour
+
+	// Case 1: Missing dates only
+	obs1 := FreshnessObservation{
+		Schedule:     "daily-daily",
+		Provider:     market.ProviderKIS,
+		Status:       "success",
+		MissingDates: []time.Time{time.Date(2026, 6, 15, 0, 0, 0, 0, time.UTC)},
+		ExpectedTo:   time.Date(2026, 6, 20, 0, 0, 0, 0, time.UTC),
+	}
+	dec1 := DecideBackfill(obs1, window)
+	if dec1.Status != "stale" {
+		t.Errorf("case 1 (missing): expected stale, got %s", dec1.Status)
+	}
+	if !dec1.HasBackfill {
+		t.Error("case 1 (missing): expected has_backfill=true")
+	}
+
+	// Case 2: Gap buckets only
+	obs2 := FreshnessObservation{
+		Schedule:     "daily-daily",
+		Provider:     market.ProviderKIS,
+		Status:       "success",
+		GapBuckets:   []GapBucket{{From: time.Date(2026, 6, 15, 0, 0, 0, 0, time.UTC), To: time.Date(2026, 6, 16, 0, 0, 0, 0, time.UTC)}},
+		ExpectedTo:   time.Date(2026, 6, 20, 0, 0, 0, 0, time.UTC),
+		ExpectedFrom: time.Date(2026, 6, 13, 0, 0, 0, 0, time.UTC),
+	}
+	dec2 := DecideBackfill(obs2, window)
+	if dec2.Status != "stale" {
+		t.Errorf("case 2 (gap): expected stale, got %s", dec2.Status)
+	}
+	if !dec2.HasBackfill {
+		t.Error("case 2 (gap): expected has_backfill=true")
+	}
+
+	// Case 3: Provider delay only
+	obs3 := FreshnessObservation{
+		Schedule:      "daily-daily",
+		Provider:      market.ProviderKIS,
+		Status:        "success",
+		ProviderDelay: 3,
+		ExpectedTo:    time.Date(2026, 6, 20, 0, 0, 0, 0, time.UTC),
+	}
+	dec3 := DecideBackfill(obs3, window)
+	if dec3.Status != "stale" {
+		t.Errorf("case 3 (delay): expected stale, got %s", dec3.Status)
+	}
+	if dec3.HasBackfill {
+		t.Error("case 3 (delay): expected has_backfill=false")
+	}
+	if dec3.Retry {
+		t.Error("case 3 (delay): expected retry=false")
+	}
+
+	// Case 4: Error
+	obs4 := FreshnessObservation{
+		Schedule:   "daily-daily",
+		Provider:   market.ProviderKIS,
+		Status:     "error",
+		LastError:  "api timeout",
+		ExpectedTo: time.Date(2026, 6, 20, 0, 0, 0, 0, time.UTC),
+	}
+	dec4 := DecideBackfill(obs4, window)
+	if dec4.Status != "error" {
+		t.Errorf("case 4 (error): expected error, got %s", dec4.Status)
+	}
+}
+
+func TestDecideBackfillDuplicateOnly(t *testing.T) {
+	obs := FreshnessObservation{
+		Schedule:       "daily-daily",
+		Provider:       market.ProviderKIS,
+		Selector:       "kospi",
+		Status:         "success",
+		DuplicateCount: 5,
+		ExpectedTo:     time.Date(2026, 6, 20, 0, 0, 0, 0, time.UTC),
+	}
+
+	window := 7 * 24 * time.Hour
+	dec := DecideBackfill(obs, window)
+
+	// Duplicate-only should still be fresh if no missing/gap/error.
+	if dec.Status != "fresh" {
+		t.Errorf("expected status=fresh for duplicate-only, got %s", dec.Status)
+	}
+	if dec.HasBackfill {
+		t.Error("expected has_backfill=false for duplicate-only")
+	}
+}
+
+func TestDecideBackfillBackfillWindowCutoff(t *testing.T) {
+	// Missing dates older than the backfill window should be clamped.
+	missingDates := []time.Time{
+		time.Date(2026, 6, 1, 0, 0, 0, 0, time.UTC), // older than 7-day window
+		time.Date(2026, 6, 10, 0, 0, 0, 0, time.UTC),
+	}
+	obs := FreshnessObservation{
+		Schedule:       "daily-daily",
+		Provider:       market.ProviderKIS,
+		Selector:       "kospi",
+		Status:         "success",
+		MissingDates:   missingDates,
+		ExpectedTo:     time.Date(2026, 6, 20, 0, 0, 0, 0, time.UTC),
+	}
+
+	window := 7 * 24 * time.Hour
+	dec := DecideBackfill(obs, window)
+
+	if dec.Status != "stale" {
+		t.Errorf("expected status=stale, got %s", dec.Status)
+	}
+	if !dec.HasBackfill {
+		t.Error("expected has_backfill=true")
+	}
+	// Should be clamped to window start (2026-06-13)
+	windowStart := time.Date(2026, 6, 13, 0, 0, 0, 0, time.UTC)
+	if !dec.BackfillFrom.Equal(windowStart) {
+		t.Errorf("expected backfill_from=%s, got %s", windowStart.Format("2006-01-02"), dec.BackfillFrom.Format("2006-01-02"))
+	}
+}
+
+func TestDecideBackfillNilSlices(t *testing.T) {
+	obs := FreshnessObservation{
+		Schedule:       "daily-daily",
+		Provider:       market.ProviderKIS,
+		Status:         "success",
+		MissingDates:   nil,
+		GapBuckets:     nil,
+		ExpectedTo:     time.Date(2026, 6, 20, 0, 0, 0, 0, time.UTC),
+	}
+
+	window := 7 * 24 * time.Hour
+	dec := DecideBackfill(obs, window)
+
+	if dec.Status != "fresh" {
+		t.Errorf("expected status=fresh for nil slices, got %s", dec.Status)
+	}
+}
+
+func TestWriteBackfillTextAndJSONL(t *testing.T) {
+	decisions := []BackfillDecision{
+		{
+			Schedule:    "daily-daily",
+			Status:      "fresh",
+			Reason:      "all expected dates are present",
+			HasBackfill: false,
+			Retry:       false,
+		},
+		{
+			Schedule:     "daily-daily",
+			Status:       "stale",
+			Reason:       "backfill needed: 3 missing date(s) from 2026-06-15 to 2026-06-20",
+			HasBackfill:  true,
+			Retry:        true,
+			BackfillFrom: time.Date(2026, 6, 15, 0, 0, 0, 0, time.UTC),
+			BackfillTo:   time.Date(2026, 6, 20, 0, 0, 0, 0, time.UTC),
+			MissingCount: 3,
+			StaleDates: []time.Time{
+				time.Date(2026, 6, 15, 0, 0, 0, 0, time.UTC),
+				time.Date(2026, 6, 16, 0, 0, 0, 0, time.UTC),
+				time.Date(2026, 6, 18, 0, 0, 0, 0, time.UTC),
+			},
+		},
+		{
+			Schedule:    "daily-daily",
+			Status:      "error",
+			Reason:      "previous operation failed: connection timeout",
+			LastError:   "connection timeout",
+			HasBackfill: false,
+			Retry:       true,
+		},
+	}
+
+	// Test text output
+	var textBuf bytes.Buffer
+	if err := WriteBackfillText(&textBuf, decisions); err != nil {
+		t.Fatalf("WriteBackfillText: %v", err)
+	}
+
+	text := textBuf.String()
+	textLines := strings.Split(strings.TrimSpace(text), "\n")
+	if len(textLines) != 3 {
+		t.Errorf("expected 3 text lines, got %d", len(textLines))
+	}
+
+	// Check line 1 (fresh)
+	if !strings.Contains(textLines[0], "status=fresh") {
+		t.Errorf("line 1 should contain status=fresh: %s", textLines[0])
+	}
+	if !strings.Contains(textLines[0], "backfill_from=NONE") {
+		t.Errorf("line 1 should contain backfill_from=NONE: %s", textLines[0])
+	}
+
+	// Check line 2 (stale)
+	if !strings.Contains(textLines[1], "status=stale") {
+		t.Errorf("line 2 should contain status=stale: %s", textLines[1])
+	}
+	if !strings.Contains(textLines[1], "backfill_from=20260615") {
+		t.Errorf("line 2 should contain backfill_from=20260615: %s", textLines[1])
+	}
+	if !strings.Contains(textLines[1], "backfill_to=20260620") {
+		t.Errorf("line 2 should contain backfill_to=20260620: %s", textLines[1])
+	}
+
+	// Check line 3 (error)
+	if !strings.Contains(textLines[2], "status=error") {
+		t.Errorf("line 3 should contain status=error: %s", textLines[2])
+	}
+
+	// Test JSONL output (single-line JSON per decision, no SetIndent)
+	var jsonBuf bytes.Buffer
+	if err := WriteBackfillJSONL(&jsonBuf, decisions); err != nil {
+		t.Fatalf("WriteBackfillJSONL: %v", err)
+	}
+
+	jsonLines := strings.Split(strings.TrimSpace(jsonBuf.String()), "\n")
+	if len(jsonLines) != 3 {
+		t.Fatalf("expected 3 JSON lines, got %d", len(jsonLines))
+	}
+
+	// Parse and verify each JSON line
+	for i, jsonLine := range jsonLines {
+		var parsed map[string]interface{}
+		if err := json.Unmarshal([]byte(jsonLine), &parsed); err != nil {
+			t.Fatalf("line %d: failed to parse JSON: %v", i, err)
+		}
+
+		if parsed["schedule"] != "daily-daily" {
+			t.Errorf("line %d: expected schedule=daily-daily, got %v", i, parsed["schedule"])
+		}
+
+		expectedStatus := []string{"fresh", "stale", "error"}[i]
+		if parsed["status"] != expectedStatus {
+			t.Errorf("line %d: expected status=%s, got %v", i, expectedStatus, parsed["status"])
+		}
+
+		// Fresh case: backfill_from should not be present
+		if i == 0 {
+			if val, ok := parsed["backfill_from"]; ok && val != nil {
+				t.Errorf("line %d: expected backfill_from absent or nil for fresh, got %v", i, val)
+			}
+		}
+		// Stale case: should have stale_dates
+		if i == 1 {
+			staleDates, ok := parsed["stale_dates"].([]interface{})
+			if !ok {
+				t.Errorf("line %d: expected stale_dates to be an array, got %T", i, parsed["stale_dates"])
+			} else if len(staleDates) != 3 {
+				t.Errorf("line %d: expected 3 stale_dates, got %d", i, len(staleDates))
+			}
+		}
+		// Error case: should have last_error
+		if i == 2 {
+			if parsed["last_error"] != "connection timeout" {
+				t.Errorf("line %d: expected last_error=connection timeout, got %v", i, parsed["last_error"])
+			}
+		}
+	}
+}
+
+func TestDecideBackfillNilObservation(t *testing.T) {
+	// Empty observation with no status should not trigger error or backfill.
+	obs := FreshnessObservation{}
+
+	window := 7 * 24 * time.Hour
+	dec := DecideBackfill(obs, window)
+
+	// Should be fresh (empty = no missing, no gaps, no error).
+	if dec.Status != "fresh" {
+		t.Errorf("expected status=fresh for empty observation, got %s", dec.Status)
+	}
+}
\ No newline at end of file
diff --git a/services/worker/internal/scheduler/config.go b/services/worker/internal/scheduler/config.go
new file mode 100644
index 0000000..53dabec
--- /dev/null
+++ b/services/worker/internal/scheduler/config.go
@@ -0,0 +1,374 @@
+// Package scheduler validates scheduled market data refresh configuration and
+// renders dry-run evidence. It does not own the long-running worker loop; the
+// runner can consume the validated shapes in a later orchestration layer.
+package scheduler
+
+import (
+	"encoding/json"
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"sort"
+	"strconv"
+	"strings"
+	"time"
+
+	"git.toki-labs.com/toki/alt/packages/domain/market"
+	"gopkg.in/yaml.v3"
+)
+
+const (
+	exitOK       = 0
+	exitRejected = 1
+	exitUsage    = 2
+)
+
+// Config is the top-level YAML shape for scheduled market data refresh.
+type Config struct {
+	Schedules []ScheduleConfig `yaml:"schedules"`
+}
+
+// ScheduleConfig declares one named refresh schedule.
+type ScheduleConfig struct {
+	Name             string         `yaml:"name"`
+	Provider         string         `yaml:"provider"`
+	Selector         SelectorConfig `yaml:"selector"`
+	Timeframe        string         `yaml:"timeframe"`
+	Cadence          string         `yaml:"cadence"`
+	Timezone         string         `yaml:"timezone"`
+	BackfillWindow   string         `yaml:"backfill_window"`
+	ParallelismLimit int            `yaml:"parallelism_limit"`
+}
+
+// SelectorConfig is the named universe selector for a schedule.
+type SelectorConfig struct {
+	Kind    string   `yaml:"kind"`
+	Market  string   `yaml:"market"`
+	Venue   string   `yaml:"venue"`
+	Name    string   `yaml:"name"`
+	Symbols []string `yaml:"symbols"`
+}
+
+// ValidationOptions carries deterministic inputs for dry-run validation.
+type ValidationOptions struct {
+	Now          time.Time
+	Capabilities map[market.Provider]market.ProviderCapability
+}
+
+// Validation reports every schedule's dry-run status.
+type Validation struct {
+	Items []ValidationItem
+}
+
+// HasRejected reports whether any item was rejected.
+func (v Validation) HasRejected() bool {
+	for _, item := range v.Items {
+		if item.Status == "rejected" {
+			return true
+		}
+	}
+	return false
+}
+
+// ValidationItem is a stable text/JSONL evidence row.
+type ValidationItem struct {
+	Schedule         string `json:"schedule"`
+	Status           string `json:"status"`
+	Provider         string `json:"provider,omitempty"`
+	Selector         string `json:"selector,omitempty"`
+	Timeframe        string `json:"timeframe,omitempty"`
+	Cadence          string `json:"cadence,omitempty"`
+	Timezone         string `json:"timezone,omitempty"`
+	BackfillWindow   string `json:"backfill_window,omitempty"`
+	ParallelismLimit int    `json:"parallelism_limit,omitempty"`
+	NextRun          string `json:"next_run,omitempty"`
+	Reason           string `json:"reason,omitempty"`
+}
+
+// LoadConfig reads a YAML schedule config.
+func LoadConfig(r io.Reader) (Config, error) {
+	var cfg Config
+	dec := yaml.NewDecoder(r)
+	dec.KnownFields(true)
+	if err := dec.Decode(&cfg); err != nil {
+		return Config{}, fmt.Errorf("decode schedule config: %w", err)
+	}
+	return cfg, nil
+}
+
+// ValidateConfig validates config and computes the next dry-run window.
+func ValidateConfig(cfg Config, opts ValidationOptions) Validation {
+	now := opts.Now
+	if now.IsZero() {
+		now = time.Now()
+	}
+	if len(cfg.Schedules) == 0 {
+		return Validation{Items: []ValidationItem{{
+			Schedule: "unknown",
+			Status:   "rejected",
+			Reason:   "no schedules declared",
+		}}}
+	}
+
+	seen := make(map[string]bool)
+	items := make([]ValidationItem, 0, len(cfg.Schedules))
+	for _, sched := range cfg.Schedules {
+		items = append(items, validateSchedule(sched, opts.Capabilities, now, seen))
+	}
+	return Validation{Items: items}
+}
+
+func validateSchedule(s ScheduleConfig, caps map[market.Provider]market.ProviderCapability, now time.Time, seen map[string]bool) ValidationItem {
+	name := strings.TrimSpace(s.Name)
+	if name == "" {
+		name = "unknown"
+	}
+	item := ValidationItem{
+		Schedule:         name,
+		Provider:         strings.TrimSpace(s.Provider),
+		Selector:         strings.TrimSpace(s.Selector.Name),
+		Timeframe:        strings.TrimSpace(s.Timeframe),
+		Timezone:         strings.TrimSpace(s.Timezone),
+		ParallelismLimit: s.ParallelismLimit,
+	}
+
+	var reasons []string
+	if s.Name == "" {
+		reasons = append(reasons, "name is required")
+	} else if seen[s.Name] {
+		reasons = append(reasons, fmt.Sprintf("duplicate schedule name %q", s.Name))
+	}
+	seen[s.Name] = true
+	if item.Provider == "" {
+		reasons = append(reasons, "provider is required")
+	}
+	if item.Selector == "" {
+		reasons = append(reasons, "selector.name is required")
+	}
+	if s.Selector.Kind == "" {
+		reasons = append(reasons, "selector.kind is required")
+	}
+	if s.Selector.Venue == "" {
+		reasons = append(reasons, "selector.venue is required")
+	}
+	if len(s.Selector.Symbols) == 0 {
+		reasons = append(reasons, "selector.symbols is required")
+	}
+	if s.Timeframe == "" {
+		reasons = append(reasons, "timeframe is required")
+	}
+	if s.Cadence == "" {
+		reasons = append(reasons, "cadence is required")
+	}
+	if s.Timezone == "" {
+		reasons = append(reasons, "timezone is required")
+	}
+	if s.BackfillWindow == "" {
+		reasons = append(reasons, "backfill_window is required")
+	}
+	if s.ParallelismLimit <= 0 {
+		reasons = append(reasons, "parallelism_limit must be greater than zero")
+	}
+
+	cadence, err := parseWindow(s.Cadence)
+	if err != nil {
+		reasons = append(reasons, fmt.Sprintf("invalid cadence %q: %v", s.Cadence, err))
+	} else {
+		item.Cadence = cadence.String()
+	}
+	backfill, err := parseWindow(s.BackfillWindow)
+	if err != nil {
+		reasons = append(reasons, fmt.Sprintf("invalid backfill_window %q: %v", s.BackfillWindow, err))
+	} else {
+		item.BackfillWindow = backfill.String()
+	}
+	loc, err := time.LoadLocation(s.Timezone)
+	if err != nil && s.Timezone != "" {
+		reasons = append(reasons, fmt.Sprintf("invalid timezone %q: %v", s.Timezone, err))
+	}
+	tf, tfLabel, err := parseTimeframe(s.Timeframe)
+	if err != nil {
+		reasons = append(reasons, err.Error())
+	} else {
+		item.Timeframe = tfLabel
+	}
+
+	provider := market.Provider(s.Provider)
+	capability, ok := caps[provider]
+	if s.Provider != "" && !ok {
+		reasons = append(reasons, fmt.Sprintf("unsupported provider %q", s.Provider))
+	}
+	if ok && err == nil {
+		decision := capability.CheckBars(market.ProviderCapabilityRequest{
+			Provider:  provider,
+			Market:    market.Market(s.Selector.Market),
+			Venue:     market.Venue(s.Selector.Venue),
+			Timeframe: tf,
+		})
+		if !decision.Accepted {
+			reasons = append(reasons, "unsupported provider/timeframe combination: "+decision.Reason)
+		}
+	}
+
+	if len(reasons) > 0 {
+		item.Status = "rejected"
+		item.Reason = strings.Join(reasons, "; ")
+		return item
+	}
+	item.Status = "valid"
+	item.NextRun = nextWindow(now, loc, cadence).Format(time.RFC3339)
+	return item
+}
+
+func parseTimeframe(value string) (market.Timeframe, string, error) {
+	switch strings.ToLower(strings.TrimSpace(value)) {
+	case "daily", "1d":
+		return market.TimeframeDaily, "daily", nil
+	case "monthly", "1mo":
+		return market.TimeframeMonthly, "monthly", fmt.Errorf("unsupported timeframe %q (only daily is supported)", value)
+	case "minute_1", "1m":
+		return market.TimeframeMin1, "minute_1", fmt.Errorf("unsupported timeframe %q (only daily is supported)", value)
+	case "minute_5", "5m":
+		return market.TimeframeMin5, "minute_5", fmt.Errorf("unsupported timeframe %q (only daily is supported)", value)
+	default:
+		return "", "", fmt.Errorf("unsupported timeframe %q (only daily is supported)", value)
+	}
+}
+
+func parseWindow(value string) (time.Duration, error) {
+	trimmed := strings.TrimSpace(strings.ToLower(value))
+	if trimmed == "daily" {
+		return 24 * time.Hour, nil
+	}
+	if strings.HasSuffix(trimmed, "d") && len(trimmed) > 1 {
+		days, err := strconv.Atoi(strings.TrimSuffix(trimmed, "d"))
+		if err != nil || days <= 0 {
+			return 0, fmt.Errorf("expected positive day count")
+		}
+		return time.Duration(days) * 24 * time.Hour, nil
+	}
+	d, err := time.ParseDuration(trimmed)
+	if err != nil {
+		return 0, err
+	}
+	if d <= 0 {
+		return 0, fmt.Errorf("expected positive duration")
+	}
+	return d, nil
+}
+
+func nextWindow(now time.Time, loc *time.Location, cadence time.Duration) time.Time {
+	localNow := now.In(loc)
+	dayStart := time.Date(localNow.Year(), localNow.Month(), localNow.Day(), 0, 0, 0, 0, loc)
+	if !localNow.After(dayStart) {
+		return dayStart
+	}
+	elapsed := localNow.Sub(dayStart)
+	steps := elapsed/cadence + 1
+	return dayStart.Add(steps * cadence)
+}
+
+// WriteText renders stable operator-facing dry-run lines.
+func WriteText(w io.Writer, validation Validation) error {
+	for _, item := range validation.Items {
+		if item.Status == "rejected" {
+			if _, err := fmt.Fprintf(w, "schedule=%s status=rejected reason=%q\n", item.Schedule, item.Reason); err != nil {
+				return err
+			}
+			continue
+		}
+		if _, err := fmt.Fprintf(w,
+			"schedule=%s status=valid provider=%s selector=%s timeframe=%s cadence=%s timezone=%s backfill_window=%s parallelism_limit=%d next_run=%s\n",
+			item.Schedule, item.Provider, item.Selector, item.Timeframe, item.Cadence, item.Timezone, item.BackfillWindow, item.ParallelismLimit, item.NextRun,
+		); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// WriteJSONL renders one JSON object per validation item.
+func WriteJSONL(w io.Writer, validation Validation) error {
+	enc := json.NewEncoder(w)
+	for _, item := range validation.Items {
+		if err := enc.Encode(item); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// RunCheck implements the schedule config validation command.
+func RunCheck(args []string, stdout, stderr io.Writer, now func() time.Time, caps map[market.Provider]market.ProviderCapability) int {
+	fs := flag.NewFlagSet("alt-worker-schedule-check", flag.ContinueOnError)
+	fs.SetOutput(stderr)
+	file := fs.String("file", "", "path to schedule YAML file")
+	output := fs.String("output", "text", "output format: text or jsonl")
+	at := fs.String("at", "", "dry-run reference time in RFC3339")
+	if err := fs.Parse(args); err != nil {
+		return exitUsage
+	}
+	if *file == "" {
+		fmt.Fprintln(stderr, "schedule config file is required: --file <path>")
+		return exitUsage
+	}
+	f, err := os.Open(*file)
+	if err != nil {
+		fmt.Fprintf(stderr, "open schedule config: %v\n", err)
+		return exitUsage
+	}
+	defer f.Close()
+	cfg, err := LoadConfig(f)
+	if err != nil {
+		fmt.Fprintf(stderr, "validate schedule config: %v\n", err)
+		return exitUsage
+	}
+	nowValue := now()
+	if *at != "" {
+		parsed, err := time.Parse(time.RFC3339, *at)
+		if err != nil {
+			fmt.Fprintf(stderr, "invalid --at time %q: %v\n", *at, err)
+			return exitUsage
+		}
+		nowValue = parsed
+	}
+	validation := ValidateConfig(cfg, ValidationOptions{Now: nowValue, Capabilities: caps})
+	switch *output {
+	case "text":
+		err = WriteText(stdout, validation)
+	case "jsonl":
+		err = WriteJSONL(stdout, validation)
+	default:
+		fmt.Fprintf(stderr, "unknown output format %q (want text or jsonl)\n", *output)
+		return exitUsage
+	}
+	if err != nil {
+		fmt.Fprintf(stderr, "write schedule validation: %v\n", err)
+		return exitUsage
+	}
+	if validation.HasRejected() {
+		return exitRejected
+	}
+	return exitOK
+}
+
+// CapabilityMap builds a deterministic capability map for callers.
+func CapabilityMap(capabilities ...market.ProviderCapability) map[market.Provider]market.ProviderCapability {
+	out := make(map[market.Provider]market.ProviderCapability, len(capabilities))
+	for _, capability := range capabilities {
+		out[capability.Provider] = capability
+	}
+	return out
+}
+
+// SortedScheduleNames returns names in deterministic order for future status
+// surfaces without exposing internal map iteration order.
+func SortedScheduleNames(cfg Config) []string {
+	names := make([]string, 0, len(cfg.Schedules))
+	for _, sched := range cfg.Schedules {
+		names = append(names, sched.Name)
+	}
+	sort.Strings(names)
+	return names
+}
diff --git a/services/worker/internal/scheduler/config_test.go b/services/worker/internal/scheduler/config_test.go
new file mode 100644
index 0000000..3ff9f0e
--- /dev/null
+++ b/services/worker/internal/scheduler/config_test.go
@@ -0,0 +1,170 @@
+package scheduler
+
+import (
+	"bytes"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"git.toki-labs.com/toki/alt/packages/domain/market"
+)
+
+func testCapability() market.ProviderCapability {
+	return market.ProviderCapability{
+		Provider: market.ProviderKIS,
+		Rules: []market.ProviderCapabilityRule{
+			{
+				Market: market.MarketKR,
+				Venue:  market.VenueKRX,
+				AssetTypes: map[market.AssetType]bool{
+					market.AssetTypeEquity: true,
+				},
+				Timeframes: map[market.Timeframe]bool{
+					market.TimeframeDaily: true,
+				},
+			},
+		},
+	}
+}
+
+func TestValidateConfigReportsNextWindowAndRejectedCombination(t *testing.T) {
+	cfg, err := LoadConfig(strings.NewReader(`
+schedules:
+  - name: kr-core-daily
+    provider: kis
+    selector:
+      kind: watchlist
+      market: KR
+      venue: KRX
+      name: kr-core
+      symbols: ["005930", "000660"]
+    timeframe: daily
+    cadence: daily
+    timezone: Asia/Seoul
+    backfill_window: 3d
+    parallelism_limit: 2
+  - name: kr-core-monthly
+    provider: kis
+    selector:
+      kind: watchlist
+      market: KR
+      venue: KRX
+      name: kr-core
+      symbols: ["005930"]
+    timeframe: monthly
+    cadence: daily
+    timezone: Asia/Seoul
+    backfill_window: 3d
+    parallelism_limit: 1
+`))
+	if err != nil {
+		t.Fatalf("LoadConfig: %v", err)
+	}
+	now := time.Date(2026, 6, 21, 10, 30, 0, 0, time.UTC)
+	result := ValidateConfig(cfg, ValidationOptions{
+		Now:          now,
+		Capabilities: CapabilityMap(testCapability()),
+	})
+
+	if len(result.Items) != 2 {
+		t.Fatalf("items = %d, want 2", len(result.Items))
+	}
+	valid := result.Items[0]
+	if valid.Status != "valid" {
+		t.Fatalf("first status = %q, want valid: %+v", valid.Status, valid)
+	}
+	if valid.NextRun != "2026-06-22T00:00:00+09:00" {
+		t.Errorf("next run = %q, want 2026-06-22T00:00:00+09:00", valid.NextRun)
+	}
+	if valid.Cadence != "24h0m0s" || valid.BackfillWindow != "72h0m0s" {
+		t.Errorf("durations = %s/%s, want 24h0m0s/72h0m0s", valid.Cadence, valid.BackfillWindow)
+	}
+	rejected := result.Items[1]
+	if rejected.Status != "rejected" {
+		t.Fatalf("second status = %q, want rejected", rejected.Status)
+	}
+	if !strings.Contains(rejected.Reason, "unsupported timeframe") {
+		t.Errorf("rejection reason %q missing unsupported timeframe", rejected.Reason)
+	}
+}
+
+func TestWriteTextAndJSONL(t *testing.T) {
+	validation := Validation{Items: []ValidationItem{
+		{
+			Schedule:         "kr-core-daily",
+			Status:           "valid",
+			Provider:         "kis",
+			Selector:         "kr-core",
+			Timeframe:        "daily",
+			Cadence:          "24h0m0s",
+			Timezone:         "Asia/Seoul",
+			BackfillWindow:   "72h0m0s",
+			ParallelismLimit: 2,
+			NextRun:          "2026-06-22T00:00:00+09:00",
+		},
+		{Schedule: "bad", Status: "rejected", Reason: "unsupported provider/timeframe combination"},
+	}}
+
+	var text bytes.Buffer
+	if err := WriteText(&text, validation); err != nil {
+		t.Fatalf("WriteText: %v", err)
+	}
+	for _, want := range []string{
+		"schedule=kr-core-daily status=valid",
+		"next_run=2026-06-22T00:00:00+09:00",
+		"schedule=bad status=rejected",
+		"unsupported provider/timeframe combination",
+	} {
+		if !strings.Contains(text.String(), want) {
+			t.Errorf("text output %q missing %q", text.String(), want)
+		}
+	}
+
+	var jsonl bytes.Buffer
+	if err := WriteJSONL(&jsonl, validation); err != nil {
+		t.Fatalf("WriteJSONL: %v", err)
+	}
+	if !strings.Contains(jsonl.String(), `"schedule":"kr-core-daily"`) {
+		t.Errorf("jsonl output %q missing valid schedule", jsonl.String())
+	}
+	if !strings.Contains(jsonl.String(), `"status":"rejected"`) {
+		t.Errorf("jsonl output %q missing rejected status", jsonl.String())
+	}
+}
+
+func TestRunCheckReturnsRejectedWhenAnyScheduleIsRejected(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "schedule.yaml")
+	if err := os.WriteFile(path, []byte(`
+schedules:
+  - name: unsupported
+    provider: kis
+    selector:
+      kind: watchlist
+      market: KR
+      venue: KRX
+      name: kr-core
+      symbols: ["005930"]
+    timeframe: minute_1
+    cadence: 24h
+    timezone: Asia/Seoul
+    backfill_window: 48h
+    parallelism_limit: 1
+`), 0644); err != nil {
+		t.Fatalf("write fixture: %v", err)
+	}
+
+	var stdout, stderr bytes.Buffer
+	code := RunCheck([]string{"--file", path, "--output", "jsonl", "--at", "2026-06-21T10:30:00Z"}, &stdout, &stderr, func() time.Time {
+		return time.Date(2026, 6, 21, 10, 30, 0, 0, time.UTC)
+	}, CapabilityMap(testCapability()))
+
+	if code != exitRejected {
+		t.Fatalf("exit code = %d, want %d (stderr=%q stdout=%q)", code, exitRejected, stderr.String(), stdout.String())
+	}
+	if !strings.Contains(stdout.String(), `"status":"rejected"`) {
+		t.Errorf("stdout %q missing rejected JSONL", stdout.String())
+	}
+}
diff --git a/services/worker/internal/scheduler/runner.go b/services/worker/internal/scheduler/runner.go
new file mode 100644
index 0000000..7e2048e
--- /dev/null
+++ b/services/worker/internal/scheduler/runner.go
@@ -0,0 +1,244 @@
+package scheduler
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"sort"
+	"sync"
+	"time"
+
+	"git.toki-labs.com/toki/alt/packages/domain/market"
+	"git.toki-labs.com/toki/alt/services/worker/internal/jobs"
+)
+
+// Executor represents the job execution engine.
+type Executor interface {
+	Execute(ctx context.Context, job jobs.Job) error
+}
+
+// TickOptions provides parameters for executing a tick.
+type TickOptions struct {
+	Now          time.Time
+	Capabilities map[market.Provider]market.ProviderCapability
+	Executor     Executor
+}
+
+// TickResult represents the outcome of a single scheduler tick.
+type TickResult struct {
+	Items []ItemResult
+}
+
+// ItemResult represents the outcome of a single symbol import within a schedule.
+type ItemResult struct {
+	Schedule  string `json:"schedule"`
+	Symbol    string `json:"symbol"`
+	Status    string `json:"status"` // "succeeded", "failed", "skipped"
+	Provider  string `json:"provider"`
+	Timeframe string `json:"timeframe"`
+	Readiness string `json:"readiness"`
+	Freshness string `json:"freshness"`
+	Error     string `json:"error,omitempty"`
+}
+
+var (
+	activeJobs   = make(map[string]bool)
+	activeJobsMu sync.Mutex
+)
+
+// resetActiveJobs clears the active running schedules (for testing).
+func resetActiveJobs() {
+	activeJobsMu.Lock()
+	defer activeJobsMu.Unlock()
+	activeJobs = make(map[string]bool)
+}
+
+func currentWindow(now time.Time, loc *time.Location, cadence time.Duration) time.Time {
+	next := nextWindow(now, loc, cadence)
+	return next.Add(-cadence)
+}
+
+// RunTick triggers the periodic import task scheduler.
+func RunTick(ctx context.Context, cfg Config, opts TickOptions) (TickResult, error) {
+	now := opts.Now
+	if now.IsZero() {
+		now = time.Now()
+	}
+
+	validation := ValidateConfig(cfg, ValidationOptions{
+		Now:          now,
+		Capabilities: opts.Capabilities,
+	})
+
+	var results []ItemResult
+	var resultsMu sync.Mutex
+	var wg sync.WaitGroup
+
+	for i, sched := range cfg.Schedules {
+		valItem := validation.Items[i]
+		if valItem.Status != "valid" {
+			continue
+		}
+
+		wg.Add(1)
+		go func(s ScheduleConfig) {
+			defer wg.Done()
+
+			loc, err := time.LoadLocation(s.Timezone)
+			if err != nil {
+				return
+			}
+			cadence, _ := parseWindow(s.Cadence)
+			backfill, _ := parseWindow(s.BackfillWindow)
+
+			windowTime := currentWindow(now, loc, cadence)
+			lockKey := fmt.Sprintf("%s:%s", s.Name, windowTime.Format(time.RFC3339))
+
+			activeJobsMu.Lock()
+			if activeJobs[lockKey] {
+				activeJobsMu.Unlock()
+				resultsMu.Lock()
+				for _, sym := range s.Selector.Symbols {
+					results = append(results, ItemResult{
+						Schedule:  s.Name,
+						Symbol:    sym,
+						Status:    "skipped",
+						Provider:  s.Provider,
+						Timeframe: s.Timeframe,
+						Readiness: "stale",
+						Freshness: "stale",
+						Error:     "duplicate window running",
+					})
+				}
+				resultsMu.Unlock()
+				return
+			}
+			activeJobs[lockKey] = true
+			activeJobsMu.Unlock()
+
+			defer func() {
+				activeJobsMu.Lock()
+				delete(activeJobs, lockKey)
+				activeJobsMu.Unlock()
+			}()
+
+			sem := make(chan struct{}, s.ParallelismLimit)
+			var schedWg sync.WaitGroup
+
+			for _, sym := range s.Selector.Symbols {
+				schedWg.Add(1)
+				sem <- struct{}{}
+
+				go func(symbol string) {
+					defer func() {
+						<-sem
+						schedWg.Done()
+					}()
+
+					fromTime := windowTime.Add(-backfill)
+					payload := jobs.DailyBarImportPayload{
+						Provider:     s.Provider,
+						SelectorKind: s.Selector.Kind,
+						Market:       s.Selector.Market,
+						Venue:        s.Selector.Venue,
+						Name:         s.Selector.Name,
+						Symbols:      []string{symbol},
+						From:         fromTime.Format("20060102"),
+						To:           windowTime.Format("20060102"),
+						Timeframe:    s.Timeframe,
+					}
+
+					payloadJSON, err := json.Marshal(payload)
+					if err != nil {
+						resultsMu.Lock()
+						results = append(results, ItemResult{
+							Schedule:  s.Name,
+							Symbol:    symbol,
+							Status:    "failed",
+							Provider:  s.Provider,
+							Timeframe: s.Timeframe,
+							Readiness: "error",
+							Freshness: "stale",
+							Error:     fmt.Sprintf("marshal payload: %v", err),
+						})
+						resultsMu.Unlock()
+						return
+					}
+
+					jobID := fmt.Sprintf("sched-%s-%s-%d", s.Name, symbol, windowTime.Unix())
+					job := jobs.Job{
+						ID:      jobID,
+						Kind:    jobs.KindImportDailyBars,
+						Payload: payloadJSON,
+					}
+
+					execErr := opts.Executor.Execute(ctx, job)
+
+					itemRes := ItemResult{
+						Schedule:  s.Name,
+						Symbol:    symbol,
+						Provider:  s.Provider,
+						Timeframe: s.Timeframe,
+					}
+
+					if execErr != nil {
+						itemRes.Status = "failed"
+						itemRes.Readiness = "error"
+						itemRes.Freshness = "stale"
+						itemRes.Error = execErr.Error()
+					} else {
+						itemRes.Status = "succeeded"
+						itemRes.Readiness = "ready"
+						itemRes.Freshness = "fresh"
+					}
+
+					resultsMu.Lock()
+					results = append(results, itemRes)
+					resultsMu.Unlock()
+				}(sym)
+			}
+			schedWg.Wait()
+		}(sched)
+	}
+
+	wg.Wait()
+
+	sort.Slice(results, func(i, j int) bool {
+		if results[i].Schedule != results[j].Schedule {
+			return results[i].Schedule < results[j].Schedule
+		}
+		return results[i].Symbol < results[j].Symbol
+	})
+
+	return TickResult{Items: results}, nil
+}
+
+// WriteTickText renders stable tick result lines.
+func WriteTickText(w io.Writer, result TickResult) error {
+	for _, item := range result.Items {
+		if item.Error != "" {
+			if _, err := fmt.Fprintf(w, "schedule=%s symbol=%s status=%s provider=%s timeframe=%s readiness=%s freshness=%s error=%q\n",
+				item.Schedule, item.Symbol, item.Status, item.Provider, item.Timeframe, item.Readiness, item.Freshness, item.Error); err != nil {
+				return err
+			}
+		} else {
+			if _, err := fmt.Fprintf(w, "schedule=%s symbol=%s status=%s provider=%s timeframe=%s readiness=%s freshness=%s\n",
+				item.Schedule, item.Symbol, item.Status, item.Provider, item.Timeframe, item.Readiness, item.Freshness); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+// WriteTickJSONL renders one JSON object per tick item.
+func WriteTickJSONL(w io.Writer, result TickResult) error {
+	enc := json.NewEncoder(w)
+	for _, item := range result.Items {
+		if err := enc.Encode(item); err != nil {
+			return err
+		}
+	}
+	return nil
+}
diff --git a/services/worker/internal/scheduler/runner_test.go b/services/worker/internal/scheduler/runner_test.go
new file mode 100644
index 0000000..579786b
--- /dev/null
+++ b/services/worker/internal/scheduler/runner_test.go
@@ -0,0 +1,392 @@
+package scheduler
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	"git.toki-labs.com/toki/alt/services/worker/internal/jobs"
+	"git.toki-labs.com/toki/alt/services/worker/internal/marketdata/importer"
+)
+
+type fakeExecutor struct {
+	mu           sync.Mutex
+	activeCount  int
+	maxActive    int
+	executedJobs []jobs.Job
+	executeFn    func(ctx context.Context, job jobs.Job) error
+}
+
+func (f *fakeExecutor) Execute(ctx context.Context, job jobs.Job) error {
+	f.mu.Lock()
+	f.activeCount++
+	if f.activeCount > f.maxActive {
+		f.maxActive = f.activeCount
+	}
+	f.executedJobs = append(f.executedJobs, job)
+	f.mu.Unlock()
+
+	defer func() {
+		f.mu.Lock()
+		f.activeCount--
+		f.mu.Unlock()
+	}()
+
+	if f.executeFn != nil {
+		return f.executeFn(ctx, job)
+	}
+	return nil
+}
+
+func TestRunTickDispatchesItemsWithBoundedParallelism(t *testing.T) {
+	resetActiveJobs()
+	cfg := Config{
+		Schedules: []ScheduleConfig{
+			{
+				Name:     "kr-daily-parallel",
+				Provider: "kis",
+				Selector: SelectorConfig{
+					Kind:    "watchlist",
+					Market:  "KR",
+					Venue:   "KRX",
+					Name:    "watchlist1",
+					Symbols: []string{"A", "B", "C", "D"},
+				},
+				Timeframe:        "daily",
+				Cadence:          "daily",
+				Timezone:         "Asia/Seoul",
+				BackfillWindow:   "3d",
+				ParallelismLimit: 2,
+			},
+		},
+	}
+
+	exec := &fakeExecutor{
+		executeFn: func(ctx context.Context, job jobs.Job) error {
+			time.Sleep(10 * time.Millisecond)
+			return nil
+		},
+	}
+
+	opts := TickOptions{
+		Now:          time.Date(2026, 6, 21, 10, 30, 0, 0, time.UTC),
+		Capabilities: CapabilityMap(testCapability()),
+		Executor:     exec,
+	}
+
+	res, err := RunTick(context.Background(), cfg, opts)
+	if err != nil {
+		t.Fatalf("RunTick: %v", err)
+	}
+
+	if len(res.Items) != 4 {
+		t.Errorf("expected 4 item results, got %d", len(res.Items))
+	}
+
+	if exec.maxActive > 2 {
+		t.Errorf("max concurrent jobs %d exceeded parallelism limit 2", exec.maxActive)
+	}
+
+	for _, item := range res.Items {
+		if item.Status != "succeeded" {
+			t.Errorf("expected succeeded status, got %s", item.Status)
+		}
+	}
+}
+
+func TestRunTickSkipsDuplicateRunningWindow(t *testing.T) {
+	resetActiveJobs()
+	cfg := Config{
+		Schedules: []ScheduleConfig{
+			{
+				Name:     "kr-daily-dup",
+				Provider: "kis",
+				Selector: SelectorConfig{
+					Kind:    "watchlist",
+					Market:  "KR",
+					Venue:   "KRX",
+					Name:    "watchlist1",
+					Symbols: []string{"A"},
+				},
+				Timeframe:        "daily",
+				Cadence:          "daily",
+				Timezone:         "Asia/Seoul",
+				BackfillWindow:   "3d",
+				ParallelismLimit: 1,
+			},
+		},
+	}
+
+	startChan := make(chan struct{})
+	doneChan := make(chan struct{})
+
+	exec := &fakeExecutor{
+		executeFn: func(ctx context.Context, job jobs.Job) error {
+			close(startChan)
+			<-doneChan
+			return nil
+		},
+	}
+
+	opts := TickOptions{
+		Now:          time.Date(2026, 6, 21, 10, 30, 0, 0, time.UTC),
+		Capabilities: CapabilityMap(testCapability()),
+		Executor:     exec,
+	}
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		_, _ = RunTick(context.Background(), cfg, opts)
+	}()
+
+	<-startChan // Wait until first tick starts executing
+
+	res2, err := RunTick(context.Background(), cfg, opts)
+	if err != nil {
+		t.Fatalf("second RunTick: %v", err)
+	}
+
+	if len(res2.Items) != 1 {
+		t.Fatalf("expected 1 result in duplicate run, got %d", len(res2.Items))
+	}
+	if res2.Items[0].Status != "skipped" {
+		t.Errorf("expected duplicate run to be skipped, got %s", res2.Items[0].Status)
+	}
+	if res2.Items[0].Error != "duplicate window running" {
+		t.Errorf("expected error string duplicate window running, got %q", res2.Items[0].Error)
+	}
+
+	close(doneChan)
+	wg.Wait()
+
+	// Sequential 2nd run
+	exec3 := &fakeExecutor{}
+	opts3 := TickOptions{
+		Now:          time.Date(2026, 6, 21, 10, 30, 0, 0, time.UTC),
+		Capabilities: CapabilityMap(testCapability()),
+		Executor:     exec3,
+	}
+	res3, err := RunTick(context.Background(), cfg, opts3)
+	if err != nil {
+		t.Fatalf("third sequential RunTick: %v", err)
+	}
+	if len(res3.Items) != 1 {
+		t.Fatalf("expected 1 result, got %d", len(res3.Items))
+	}
+	if res3.Items[0].Status != "succeeded" {
+		t.Errorf("expected succeeded status, got %s", res3.Items[0].Status)
+	}
+}
+
+func TestWriteTickJSONLIncludesReadinessFields(t *testing.T) {
+	res := TickResult{
+		Items: []ItemResult{
+			{
+				Schedule:  "test-sched",
+				Symbol:    "AAPL",
+				Status:    "succeeded",
+				Provider:  "kis",
+				Timeframe: "daily",
+				Readiness: "ready",
+				Freshness: "fresh",
+			},
+			{
+				Schedule:  "test-sched",
+				Symbol:    "MSFT",
+				Status:    "failed",
+				Provider:  "kis",
+				Timeframe: "daily",
+				Readiness: "error",
+				Freshness: "stale",
+				Error:     "network error",
+			},
+		},
+	}
+
+	var jsonl bytes.Buffer
+	if err := WriteTickJSONL(&jsonl, res); err != nil {
+		t.Fatalf("WriteTickJSONL: %v", err)
+	}
+
+	lines := strings.Split(strings.TrimSpace(jsonl.String()), "\n")
+	if len(lines) != 2 {
+		t.Fatalf("expected 2 JSONL lines, got %d", len(lines))
+	}
+
+	if !strings.Contains(lines[0], `"readiness":"ready"`) || !strings.Contains(lines[0], `"freshness":"fresh"`) {
+		t.Errorf("line 0 missing readiness/freshness fields: %s", lines[0])
+	}
+	if !strings.Contains(lines[1], `"readiness":"error"`) || !strings.Contains(lines[1], `"freshness":"stale"`) {
+		t.Errorf("line 1 missing readiness/freshness fields: %s", lines[1])
+	}
+
+	var text bytes.Buffer
+	if err := WriteTickText(&text, res); err != nil {
+		t.Fatalf("WriteTickText: %v", err)
+	}
+	textLines := strings.Split(strings.TrimSpace(text.String()), "\n")
+	if len(textLines) != 2 {
+		t.Fatalf("expected 2 text lines, got %d", len(textLines))
+	}
+	if !strings.Contains(textLines[0], "readiness=ready freshness=fresh") {
+		t.Errorf("text line 0 missing readiness/freshness: %s", textLines[0])
+	}
+	if !strings.Contains(textLines[1], "readiness=error freshness=stale") {
+		t.Errorf("text line 1 missing readiness/freshness: %s", textLines[1])
+	}
+}
+
+type fakeDailyBarImporter struct {
+	mu           sync.Mutex
+	upsertedBars map[string]int
+}
+
+func (f *fakeDailyBarImporter) ImportDailyBars(ctx context.Context, request importer.DailyBarRequest) (importer.Result, error) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+
+	timeframe := "daily"
+	days := int(request.To.Sub(request.From).Hours()/24) + 1
+	for _, sym := range request.Selector.Symbols {
+		for i := 0; i < days; i++ {
+			t := request.From.Add(time.Duration(i) * 24 * time.Hour)
+			dateStr := t.Format("2006-01-02")
+			key := fmt.Sprintf("%s:%s:%s", sym, timeframe, dateStr)
+			f.upsertedBars[key]++
+		}
+	}
+	return importer.Result{
+		Instruments: len(request.Selector.Symbols),
+		Bars:        len(request.Selector.Symbols) * days,
+	}, nil
+}
+
+func TestRunTickSequentialTicksDoNotDuplicateBarKeys(t *testing.T) {
+	resetActiveJobs()
+
+	fakeImp := &fakeDailyBarImporter{
+		upsertedBars: make(map[string]int),
+	}
+
+	runner := jobs.NewRunner()
+	jobs.RegisterBuiltins(runner)
+	cap := testCapability()
+	jobs.RegisterDailyBarImportHandler(runner, cap, fakeImp)
+
+	cfg := Config{
+		Schedules: []ScheduleConfig{
+			{
+				Name:             "kr-daily-dup-assert",
+				Provider:         "kis",
+				Selector: SelectorConfig{
+					Kind:    "watchlist",
+					Market:  "KR",
+					Venue:   "KRX",
+					Name:    "watchlist1",
+					Symbols: []string{"005930"},
+				},
+				Timeframe:        "daily",
+				Cadence:          "daily",
+				Timezone:         "Asia/Seoul",
+				BackfillWindow:   "3d",
+				ParallelismLimit: 1,
+			},
+		},
+	}
+
+	opts := TickOptions{
+		Now:          time.Date(2026, 6, 21, 10, 30, 0, 0, time.UTC),
+		Capabilities: CapabilityMap(cap),
+		Executor:     runner,
+	}
+
+	// 1st tick
+	res1, err := RunTick(context.Background(), cfg, opts)
+	if err != nil {
+		t.Fatalf("first tick: %v", err)
+	}
+	if len(res1.Items) != 1 || res1.Items[0].Status != "succeeded" {
+		t.Fatalf("expected succeeded in 1st tick, got: %+v", res1.Items)
+	}
+
+	fakeImp.mu.Lock()
+	keysCount1 := len(fakeImp.upsertedBars)
+	if keysCount1 == 0 {
+		fakeImp.mu.Unlock()
+		t.Fatal("expected upserted bars count > 0")
+	}
+	for k, count := range fakeImp.upsertedBars {
+		if count != 1 {
+			t.Errorf("expected key %s count to be 1, got %d", k, count)
+		}
+	}
+	fakeImp.mu.Unlock()
+
+	// 2nd tick
+	res2, err := RunTick(context.Background(), cfg, opts)
+	if err != nil {
+		t.Fatalf("second tick: %v", err)
+	}
+	if len(res2.Items) != 1 || res2.Items[0].Status != "succeeded" {
+		t.Fatalf("expected succeeded in 2nd tick, got: %+v", res2.Items)
+	}
+
+	fakeImp.mu.Lock()
+	keysCount2 := len(fakeImp.upsertedBars)
+	if keysCount2 != keysCount1 {
+		t.Errorf("expected unique key count to be %d, got %d (duplicated keys detected)", keysCount1, keysCount2)
+	}
+	for k, count := range fakeImp.upsertedBars {
+		if count != 2 {
+			t.Errorf("expected key %s count to be 2 after second tick, got %d", k, count)
+		}
+	}
+	fakeImp.mu.Unlock()
+}
+
+func TestRunTickOutputCarriesS02Evidence(t *testing.T) {
+	res := TickResult{
+		Items: []ItemResult{
+			{
+				Schedule:  "test-sched",
+				Symbol:    "AAPL",
+				Status:    "succeeded",
+				Provider:  "kis",
+				Timeframe: "daily",
+				Readiness: "ready",
+				Freshness: "fresh",
+			},
+		},
+	}
+
+	var jsonl bytes.Buffer
+	if err := WriteTickJSONL(&jsonl, res); err != nil {
+		t.Fatalf("WriteTickJSONL: %v", err)
+	}
+
+	outStr := jsonl.String()
+	for _, expected := range []string{`"status":"succeeded"`, `"readiness":"ready"`, `"freshness":"fresh"`, `"schedule":"test-sched"`, `"symbol":"AAPL"`} {
+		if !strings.Contains(outStr, expected) {
+			t.Errorf("JSONL output missing expected pattern %q: %s", expected, outStr)
+		}
+	}
+
+	var text bytes.Buffer
+	if err := WriteTickText(&text, res); err != nil {
+		t.Fatalf("WriteTickText: %v", err)
+	}
+
+	textStr := text.String()
+	for _, expected := range []string{"status=succeeded", "readiness=ready", "freshness=fresh", "schedule=test-sched", "symbol=AAPL"} {
+		if !strings.Contains(textStr, expected) {
+			t.Errorf("Text output missing expected pattern %q: %s", expected, textStr)
+		}
+	}
+}
+