diff --git a/BACKLOG.md b/BACKLOG.md
index 90ca888..95631cb 100644
--- a/BACKLOG.md
+++ b/BACKLOG.md
@@ -431,7 +431,14 @@ portal is not done — the page shows; the console and ctl change.
    weighted routing across two revisions/aliases (scheduler filter, alias
    resolution in `router/router.go:569`), a header/key pin, automatic
    rollback on error-rate or TTFT regression from per-replica metrics.
-8. **Batch API and Files (M–L).** `/v1/files`, `/v1/batches`, JSONL
+8. **Done (branch `features-c2`):** `/v1/files` and `/v1/batches`
+   (OpenAI's shape), worker under a store lease, lines kept as served,
+   lowest band, usage tagged `batch=<id>`, output and error files with
+   retention, `no_store` refused. Left: the Responses API (`/v1/responses`)
+   as a batch endpoint; the console and `ctl` do not list batches (an
+   operator sees them through usage tags); a file is one row in the store,
+   so a store backup carries batch files with it.
+   **Batch API and Files (M–L).** `/v1/files`, `/v1/batches`, JSONL
    storage, a worker feeding the bronze band, accounting. New
    `internal/router/batch`.
 9. **Request/response logging and replay (M).** Opt-in per project with
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7bda153..b8c411b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -71,6 +71,21 @@ APIs change between minors without a deprecation period.
   - **Other ways in:** `GET /api/v1/usage/export` (CSV, or `format=json`)
     and **E** on the console's Usage view.
 
+### Batches
+
+- **OpenAI's Batch and Files APIs.** `POST /v1/files` (purpose batch),
+  `POST /v1/batches`, and reading, listing, cancelling and deleting them, so
+  OpenAI's clients send batches here unchanged.
+  - **Serving:** each line goes as a request of the key that made the batch,
+    in the lowest admission band, a few at a time; rate limits are waited
+    out. Answers and failures are written to files kept 30 days.
+  - **Accounting:** each line is an ordinary usage record tagged
+    `batch=<id>`.
+  - **Restarts:** answered lines are kept as they are answered, and any
+    gateway on the store carries a batch on under a lease.
+  - **Limits:** `router.batch` bounds the file, the lines and the
+    concurrency. Refused to a project under a `no_store` policy.
+
 ### New weights tried on a share of the traffic first
 
 - **Canaries.** `llmgw ctl model canary MODEL --percent 10` fetches the newer
diff --git a/docs/data.md b/docs/data.md
index c103c23..6d3cf02 100644
--- a/docs/data.md
+++ b/docs/data.md
@@ -51,10 +51,17 @@ limits attached to it. Passwords are hashed.
 
 **Conversations and agent notes** — only for a project that asked. See below.
 
+**Batch files** — when a client uses the Batch API: the file of requests it
+uploaded (prompts) and the files the batch wrote (answers), in the store,
+until deleted (`DELETE /v1/files/{id}`) or, for what a batch wrote, until
+`router.batch.retain_days` (30) pass. Only keys of the project that made
+them can read them, and a project under a `no_store` policy cannot make
+them.
+
 ## What is not stored
 
 Prompts. Completions. Anything the model was shown or produced, unless the
-project turned on conversations or notes.
+project turned on conversations or notes, or sent a batch.
 
 The chat page in llmgw's own web interface keeps the conversation in a
 JavaScript variable in the browser. Refresh it and the conversation is gone,
diff --git a/docs/install.md b/docs/install.md
index fae8cd8..ae7b9f6 100644
--- a/docs/install.md
+++ b/docs/install.md
@@ -1130,6 +1130,42 @@ curl http://gateway:8080/v1/chat/completions \
   100 values of each apart and the rest as `other`: a tag is the client's
   to set, and every value is a series.
 
+## Batches
+
+Work that can wait — a night's classification, embeddings for a document
+store — goes as a batch: OpenAI's Batch API, so its clients work unchanged.
+
+```
+curl http://gateway:8080/v1/files -H "Authorization: Bearer $LLMGW_API_KEY" \
+  -F purpose=batch -F file=@requests.jsonl
+curl http://gateway:8080/v1/batches -H "Authorization: Bearer $LLMGW_API_KEY" \
+  -d '{"input_file_id": "file-…", "endpoint": "/v1/chat/completions", "completion_window": "24h"}'
+curl http://gateway:8080/v1/batches/batch_… -H "Authorization: Bearer $LLMGW_API_KEY"
+curl http://gateway:8080/v1/files/file-…/content -H "Authorization: Bearer $LLMGW_API_KEY"
+```
+
+Each line of the file is `{"custom_id": …, "method": "POST", "url":
+"/v1/chat/completions", "body": {…}}`, at most 50 000 of them
+(`router.batch.max_lines`) in at most 100 MB (`router.batch.max_file_bytes`).
+
+- **How it is served:** each line as a request of the key that made the
+  batch — its limits, its budget, its guardrails — in the lowest admission
+  band, behind every interactive request, `router.batch.concurrency` (4) at
+  a time. A rate limit or a model still loading is waited out; a spent
+  budget fails the lines left.
+- **What comes back:** answers in an output file, failures in an error
+  file, both OpenAI's form, kept `router.batch.retain_days` (30). Each
+  request is a usage record tagged `batch=<id>`, so `llmgw ctl request`
+  finds it.
+- **Who sees it:** files and batches belong to the key's project; every key
+  of the project sees them, no other does.
+- **Surviving a restart:** every answered line is kept as it is answered,
+  and whichever gateway holds the batch's lease carries on from there; a
+  control plane that stops hands its batches to another within two minutes.
+- **What it keeps:** a batch is prompts and answers stored until deleted
+  or past their retention — a project under a guardrails policy with
+  `no_store` is refused it.
+
 ## Conversations across models
 
 Off everywhere until a project asks. llmgw otherwise stores no message content
diff --git a/docs/reference.md b/docs/reference.md
index 575d192..0360627 100644
--- a/docs/reference.md
+++ b/docs/reference.md
@@ -43,6 +43,10 @@ rather than repeated.
 | `batch_size` | `int` | [Auth](#auth) |
 | `buffer_size` | `int` | [Auth](#auth) |
 | `usage_retention` | `time.Duration` | [Auth](#auth) |
+| `max_file_bytes` | `int64` | [Batch](#batch) |
+| `max_lines` | `int` | [Batch](#batch) |
+| `concurrency` | `int` | [Batch](#batch) |
+| `retain_days` | `int` | [Batch](#batch) |
 | `model` | `string` | [Canary](#canary) |
 | `percent` | `int` | [Canary](#canary) |
 | `min_requests` | `int` | [Canary](#canary) |
@@ -198,6 +202,7 @@ rather than repeated.
 | `tenant_label` | `string` | [Router](#router) |
 | `tag_labels` | `[]string` | [Router](#router) |
 | `max_body_bytes` | `int64` | [Router](#router) |
+| `batch` | `Batch` | [Router](#router) |
 | `trusted_proxies` | `[]string` | [Router](#router) |
 | `timeouts` | `Timeouts` | [Router](#router) |
 | `scoring` | `Scoring` | [Router](#router) |
@@ -517,6 +522,35 @@ five-minute sums kept beside the records, which are not pruned, so this
 bounds the table that grows by a row a request without changing any
 figure a page shows. At least a day when set.
 
+## Batch
+
+### `max_file_bytes`
+
+`int64`
+
+MaxFileBytes bounds one uploaded file; 100 MB unless set.
+
+### `max_lines`
+
+`int`
+
+MaxLines bounds the requests in one batch; 50 000 unless set.
+
+### `concurrency`
+
+`int`
+
+Concurrency is how many of one batch's requests are in flight at
+once; 4 unless set. They queue in the lowest admission band, behind
+every interactive request.
+
+### `retain_days`
+
+`int`
+
+RetainDays is how long a batch's answer and error files are kept;
+30 unless set. Uploaded files are kept until deleted.
+
 ## Canary
 
 ### `model`
@@ -1622,6 +1656,16 @@ a series. The first 100 values of each are counted apart, the rest as
 
 MaxBodyBytes bounds the request body the router will read.
 
+### `batch`
+
+`Batch`
+
+Batch is the Files and Batch APIs (/v1/files, /v1/batches): a file of
+requests served at the lowest priority, its answers written to
+another. Needs the store.
+
+Takes a [Batch](#batch) block.
+
 ### `trusted_proxies`
 
 `[]string`
diff --git a/internal/config/config.go b/internal/config/config.go
index d19a2e2..fcc3379 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -453,6 +453,11 @@ type Router struct {
 	// MaxBodyBytes bounds the request body the router will read.
 	MaxBodyBytes int64 `koanf:"max_body_bytes"`
 
+	// Batch is the Files and Batch APIs (/v1/files, /v1/batches): a file of
+	// requests served at the lowest priority, its answers written to
+	// another. Needs the store.
+	Batch Batch `koanf:"batch"`
+
 	// TrustedProxies are the reverse proxies in front of the client port,
 	// as addresses or CIDR prefixes. Their X-Forwarded-For, -Proto and -Host
 	// are believed; anyone else's are not, since they decide the address
@@ -553,6 +558,21 @@ type Endpoint struct {
 	Priority int     `koanf:"priority"`
 }
 
+// Batch is how the Files and Batch APIs are bounded.
+type Batch struct {
+	// MaxFileBytes bounds one uploaded file; 100 MB unless set.
+	MaxFileBytes int64 `koanf:"max_file_bytes"`
+	// MaxLines bounds the requests in one batch; 50 000 unless set.
+	MaxLines int `koanf:"max_lines"`
+	// Concurrency is how many of one batch's requests are in flight at
+	// once; 4 unless set. They queue in the lowest admission band, behind
+	// every interactive request.
+	Concurrency int `koanf:"concurrency"`
+	// RetainDays is how long a batch's answer and error files are kept;
+	// 30 unless set. Uploaded files are kept until deleted.
+	RetainDays int `koanf:"retain_days"`
+}
+
 // Default returns the configuration used when nothing is specified.
 func Default() Server {
 	return Server{
diff --git a/internal/docgen/reference_gen.go b/internal/docgen/reference_gen.go
index 9d01106..3cdf078 100644
--- a/internal/docgen/reference_gen.go
+++ b/internal/docgen/reference_gen.go
@@ -38,6 +38,12 @@ var Reference = []Block{
 		{Key: "buffer_size", Type: "int", Doc: "BufferSize bounds the queue. Beyond it records are dropped rather than\nblocking a request: losing accounting is bad, turning a stalled database\ninto an outage is worse.", Nested: ""},
 		{Key: "usage_retention", Type: "time.Duration", Doc: "UsageRetention is how long the record of each request is kept: who sent\nit, which replica answered, how long it queued — what `ctl request`\nreads. Zero keeps it for ever. Totals, charts and budgets are read from\nfive-minute sums kept beside the records, which are not pruned, so this\nbounds the table that grows by a row a request without changing any\nfigure a page shows. At least a day when set.", Nested: ""},
 	}},
+	{Package: "config", Name: "Batch", Title: "Batch", Doc: "", Fields: []Field{
+		{Key: "max_file_bytes", Type: "int64", Doc: "MaxFileBytes bounds one uploaded file; 100 MB unless set.", Nested: ""},
+		{Key: "max_lines", Type: "int", Doc: "MaxLines bounds the requests in one batch; 50 000 unless set.", Nested: ""},
+		{Key: "concurrency", Type: "int", Doc: "Concurrency is how many of one batch's requests are in flight at\nonce; 4 unless set. They queue in the lowest admission band, behind\nevery interactive request.", Nested: ""},
+		{Key: "retain_days", Type: "int", Doc: "RetainDays is how long a batch's answer and error files are kept;\n30 unless set. Uploaded files are kept until deleted.", Nested: ""},
+	}},
 	{Package: "catalog", Name: "Canary", Title: "Canary", Doc: "", Fields: []Field{
 		{Key: "model", Type: "string", Doc: "Model is the candidate: a catalog model, usually this one at newer\nweights, which clients cannot name themselves.", Nested: ""},
 		{Key: "percent", Type: "int", Doc: "Percent of requests go to it, 0 to 100.", Nested: ""},
@@ -240,6 +246,7 @@ var Reference = []Block{
 		{Key: "tenant_label", Type: "string", Doc: "TenantLabel is the level of the tree the per-tenant request series are\nlabelled by — llmgw_tenant_requests_total and its siblings: \"org\",\n\"team\" or \"project\", or \"none\" for no such series. A label per project\non a cluster of thousands is more series than Prometheus wants, and a\nteam is what an alert is usually about; \"team\" is the default.", Nested: ""},
 		{Key: "tag_labels", Type: "[]string", Doc: "TagLabels are the request tags (metadata, x-llmgw-tags) counted in\nllmgw_tagged_requests_total and llmgw_tagged_tokens_total, by value.\nOnly these: a tag is the client's to set, and every value of one is\na series. The first 100 values of each are counted apart, the rest as\n\"other\". Empty counts none; the usage records keep every tag anyway.", Nested: ""},
 		{Key: "max_body_bytes", Type: "int64", Doc: "MaxBodyBytes bounds the request body the router will read.", Nested: ""},
+		{Key: "batch", Type: "Batch", Doc: "Batch is the Files and Batch APIs (/v1/files, /v1/batches): a file of\nrequests served at the lowest priority, its answers written to\nanother. Needs the store.", Nested: "config.Batch"},
 		{Key: "trusted_proxies", Type: "[]string", Doc: "TrustedProxies are the reverse proxies in front of the client port,\nas addresses or CIDR prefixes. Their X-Forwarded-For, -Proto and -Host\nare believed; anyone else's are not, since they decide the address\nwritten into the setup scripts and whose attempts are counted where.", Nested: ""},
 		{Key: "timeouts", Type: "Timeouts", Doc: "", Nested: "config.Timeouts"},
 		{Key: "scoring", Type: "Scoring", Doc: "", Nested: "config.Scoring"},
diff --git a/internal/router/batches.go b/internal/router/batches.go
new file mode 100644
index 0000000..55373ec
--- /dev/null
+++ b/internal/router/batches.go
@@ -0,0 +1,255 @@
+package router
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"strconv"
+	"time"
+
+	"gitea.mynodes.xyz/ilker/llmgw/internal/store"
+)
+
+// The Batch API: a file of requests, served one by one at the lowest
+// priority, its answers written to another file. OpenAI's shape, so its
+// clients work unchanged.
+
+// batchEndpoints are what a batch may be of.
+var batchEndpoints = map[string]bool{
+	"/v1/chat/completions": true,
+	"/v1/completions":      true,
+	"/v1/embeddings":       true,
+}
+
+// batchWindow is the only completion window, as OpenAI has it.
+const batchWindow = "24h"
+
+func unixOrNil(t time.Time) any {
+	if t.IsZero() {
+		return nil
+	}
+	return t.Unix()
+}
+
+func strOrNil(s string) any {
+	if s == "" {
+		return nil
+	}
+	return s
+}
+
+func batchJSON(b store.Batch) map[string]any {
+	out := map[string]any{
+		"id": b.ID, "object": "batch", "endpoint": b.Endpoint, "input_file_id": b.InputFileID,
+		"completion_window": b.CompletionWindow, "status": b.Status,
+		"output_file_id": strOrNil(b.OutputFileID), "error_file_id": strOrNil(b.ErrorFileID),
+		"created_at": b.CreatedAt.Unix(), "in_progress_at": unixOrNil(b.InProgressAt),
+		"expires_at": unixOrNil(b.ExpiresAt), "finalizing_at": unixOrNil(b.FinalizingAt),
+		"completed_at": unixOrNil(b.CompletedAt), "failed_at": unixOrNil(b.FailedAt),
+		"expired_at": unixOrNil(b.ExpiredAt), "cancelling_at": unixOrNil(b.CancellingAt),
+		"cancelled_at":   unixOrNil(b.CancelledAt),
+		"request_counts": map[string]int{"total": b.Total, "completed": b.Completed, "failed": b.Failed},
+		"errors":         nil, "metadata": nil,
+	}
+	if b.Errors != "" {
+		out["errors"] = json.RawMessage(b.Errors)
+	}
+	if b.Metadata != "" {
+		out["metadata"] = json.RawMessage(b.Metadata)
+	}
+	return out
+}
+
+func (r *Router) handleCreateBatch(w http.ResponseWriter, req *http.Request) {
+	p, ok := r.batchPrincipal(w, req)
+	if !ok {
+		return
+	}
+	var in struct {
+		InputFileID      string          `json:"input_file_id"`
+		Endpoint         string          `json:"endpoint"`
+		CompletionWindow string          `json:"completion_window"`
+		Metadata         json.RawMessage `json:"metadata"`
+	}
+	if err := json.NewDecoder(io.LimitReader(req.Body, 1<<16)).Decode(&in); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid_request_error", "the request is not valid JSON: "+err.Error())
+		return
+	}
+	if !batchEndpoints[in.Endpoint] {
+		writeError(w, http.StatusBadRequest, "invalid_request_error",
+			fmt.Sprintf("endpoint %q: a batch is of /v1/chat/completions, /v1/completions or /v1/embeddings", in.Endpoint))
+		return
+	}
+	if in.CompletionWindow != batchWindow {
+		writeError(w, http.StatusBadRequest, "invalid_request_error", "completion_window is 24h")
+		return
+	}
+	meta := ""
+	if len(in.Metadata) > 0 && string(in.Metadata) != "null" {
+		if _, err := requestTags(in.Metadata, ""); err != nil {
+			writeError(w, http.StatusBadRequest, "invalid_request_error", err.Error())
+			return
+		}
+		meta = string(in.Metadata)
+	}
+	f, err := r.store.FileByID(req.Context(), in.InputFileID)
+	if errors.Is(err, store.ErrNotFound) || err == nil && (f.Owner != ownerOf(p) || f.Purpose != purposeBatch) {
+		writeErrorCode(w, http.StatusBadRequest, "invalid_request_error", "file_not_found",
+			fmt.Sprintf("no batch file %q", in.InputFileID))
+		return
+	}
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "server_error", err.Error())
+		return
+	}
+	now := time.Now()
+	b := store.Batch{ID: newID("batch_"), Owner: ownerOf(p), KeyID: p.KeyID, Endpoint: in.Endpoint,
+		InputFileID: f.ID, CompletionWindow: batchWindow, Status: store.BatchValidating,
+		CreatedAt: now, ExpiresAt: now.Add(24 * time.Hour), Metadata: meta}
+	if err := r.store.PutBatch(req.Context(), b); err != nil {
+		writeError(w, http.StatusInternalServerError, "server_error", err.Error())
+		return
+	}
+	r.wakeBatches()
+	writeJSON(w, http.StatusOK, batchJSON(b))
+}
+
+// ownedBatch is a batch the caller owns, or a 404 said.
+func (r *Router) ownedBatch(w http.ResponseWriter, req *http.Request, owner string) (store.Batch, bool) {
+	b, err := r.store.BatchByID(req.Context(), req.PathValue("id"))
+	if errors.Is(err, store.ErrNotFound) || err == nil && b.Owner != owner {
+		writeErrorCode(w, http.StatusNotFound, "invalid_request_error", "batch_not_found",
+			fmt.Sprintf("no batch %q", req.PathValue("id")))
+		return store.Batch{}, false
+	}
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "server_error", err.Error())
+		return store.Batch{}, false
+	}
+	return b, true
+}
+
+func (r *Router) handleGetBatch(w http.ResponseWriter, req *http.Request) {
+	p, ok := r.batchPrincipal(w, req)
+	if !ok {
+		return
+	}
+	if b, ok := r.ownedBatch(w, req, ownerOf(p)); ok {
+		writeJSON(w, http.StatusOK, batchJSON(b))
+	}
+}
+
+func (r *Router) handleCancelBatch(w http.ResponseWriter, req *http.Request) {
+	p, ok := r.batchPrincipal(w, req)
+	if !ok {
+		return
+	}
+	b, ok := r.ownedBatch(w, req, ownerOf(p))
+	if !ok {
+		return
+	}
+	b, err := r.store.CancelBatch(req.Context(), b.ID, time.Now())
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "server_error", err.Error())
+		return
+	}
+	r.wakeBatches()
+	writeJSON(w, http.StatusOK, batchJSON(b))
+}
+
+func (r *Router) handleListBatches(w http.ResponseWriter, req *http.Request) {
+	p, ok := r.batchPrincipal(w, req)
+	if !ok {
+		return
+	}
+	limit, _ := strconv.Atoi(req.URL.Query().Get("limit"))
+	if limit <= 0 || limit > 100 {
+		limit = 20
+	}
+	bs, err := r.store.Batches(req.Context(), ownerOf(p), req.URL.Query().Get("after"), limit+1)
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "server_error", err.Error())
+		return
+	}
+	more := len(bs) > limit
+	if more {
+		bs = bs[:limit]
+	}
+	data := make([]map[string]any, 0, len(bs))
+	for _, b := range bs {
+		data = append(data, batchJSON(b))
+	}
+	out := map[string]any{"object": "list", "data": data, "has_more": more, "first_id": nil, "last_id": nil}
+	if len(bs) > 0 {
+		out["first_id"], out["last_id"] = bs[0].ID, bs[len(bs)-1].ID
+	}
+	writeJSON(w, http.StatusOK, out)
+}
+
+// batchLine is one line of a batch's input file.
+type batchLine struct {
+	CustomID string          `json:"custom_id"`
+	Method   string          `json:"method"`
+	URL      string          `json:"url"`
+	Body     json.RawMessage `json:"body"`
+}
+
+// lineError is one reason a batch's input was refused, as OpenAI lists them.
+type lineError struct {
+	Code    string `json:"code"`
+	Message string `json:"message"`
+	Line    int    `json:"line,omitempty"`
+}
+
+// parseBatchInput reads a batch's input file, or says every line that is
+// wrong with it.
+func parseBatchInput(content []byte, endpoint string, maxLines int) ([]batchLine, []lineError) {
+	var lines []batchLine
+	var errs []lineError
+	seen := map[string]bool{}
+	n := 0
+	for raw := range bytes.SplitSeq(content, []byte("\n")) {
+		n++
+		raw = bytes.TrimSpace(raw)
+		if len(raw) == 0 {
+			continue
+		}
+		bad := func(code, msg string) {
+			if len(errs) < 100 {
+				errs = append(errs, lineError{Code: code, Message: msg, Line: n})
+			}
+		}
+		var l batchLine
+		if err := json.Unmarshal(raw, &l); err != nil {
+			bad("invalid_json_line", "not a JSON object: "+err.Error())
+			continue
+		}
+		var body map[string]any
+		switch {
+		case l.CustomID == "":
+			bad("missing_custom_id", "custom_id is required")
+		case seen[l.CustomID]:
+			bad("duplicate_custom_id", fmt.Sprintf("custom_id %q is used twice", l.CustomID))
+		case l.Method != http.MethodPost:
+			bad("invalid_method", "method is POST")
+		case l.URL != endpoint:
+			bad("mismatched_endpoint", fmt.Sprintf("url %q is not the batch's endpoint, %s", l.URL, endpoint))
+		case json.Unmarshal(l.Body, &body) != nil || body["model"] == nil:
+			bad("invalid_body", "body is an object naming a model")
+		default:
+			seen[l.CustomID] = true
+			lines = append(lines, l)
+		}
+	}
+	if len(lines)+len(errs) == 0 {
+		errs = append(errs, lineError{Code: "empty_file", Message: "the file has no requests"})
+	}
+	if len(lines) > maxLines {
+		errs = append(errs, lineError{Code: "too_many_requests",
+			Message: fmt.Sprintf("%d requests; a batch holds at most %d", len(lines), maxLines)})
+	}
+	return lines, errs
+}
diff --git a/internal/router/batches_test.go b/internal/router/batches_test.go
new file mode 100644
index 0000000..7048a4f
--- /dev/null
+++ b/internal/router/batches_test.go
@@ -0,0 +1,241 @@
+package router
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"encoding/json"
+	"fmt"
+	"mime/multipart"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"time"
+
+	"gitea.mynodes.xyz/ilker/llmgw/internal/store"
+)
+
+func upload(t *testing.T, h http.Handler, secret, content string) (int, map[string]any) {
+	t.Helper()
+	var buf bytes.Buffer
+	mw := multipart.NewWriter(&buf)
+	_ = mw.WriteField("purpose", "batch")
+	fw, _ := mw.CreateFormFile("file", "in.jsonl")
+	_, _ = fw.Write([]byte(content))
+	_ = mw.Close()
+	req := httptest.NewRequest(http.MethodPost, "/v1/files", &buf)
+	req.Header.Set("Content-Type", mw.FormDataContentType())
+	req.Header.Set("Authorization", "Bearer "+secret)
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+	var out map[string]any
+	_ = json.Unmarshal(rec.Body.Bytes(), &out)
+	return rec.Code, out
+}
+
+func call(t *testing.T, h http.Handler, secret, method, path string, body any) (int, map[string]any, string) {
+	t.Helper()
+	var rd *bytes.Reader
+	if body != nil {
+		b, _ := json.Marshal(body)
+		rd = bytes.NewReader(b)
+	} else {
+		rd = bytes.NewReader(nil)
+	}
+	req := httptest.NewRequest(method, path, rd)
+	req.Header.Set("Authorization", "Bearer "+secret)
+	req.Header.Set("Content-Type", "application/json")
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+	var out map[string]any
+	_ = json.Unmarshal(rec.Body.Bytes(), &out)
+	return rec.Code, out, rec.Body.String()
+}
+
+func waitBatch(t *testing.T, h http.Handler, secret, id string) map[string]any {
+	t.Helper()
+	deadline := time.Now().Add(10 * time.Second)
+	for {
+		_, b, _ := call(t, h, secret, http.MethodGet, "/v1/batches/"+id, nil)
+		if store.BatchDone(fmt.Sprint(b["status"])) {
+			return b
+		}
+		if time.Now().After(deadline) {
+			t.Fatalf("the batch did not end: %v", b)
+		}
+		time.Sleep(50 * time.Millisecond)
+	}
+}
+
+func TestABatchIsServedAndItsAnswersWritten(t *testing.T) {
+	e := newFakeEngine(t, "qwen2.5-14b-instruct")
+	rt, secret := pricedRouter(t, e.srv.URL)
+	h := rt.Handler()
+
+	var in strings.Builder
+	for i := range 5 {
+		fmt.Fprintf(&in, `{"custom_id":"r%d","method":"POST","url":"/v1/chat/completions","body":{"model":"q14","messages":[{"role":"user","content":"hi"}]}}`+"\n", i)
+	}
+	// One the engine cannot serve: a model that is not there.
+	in.WriteString(`{"custom_id":"bad","method":"POST","url":"/v1/chat/completions","body":{"model":"nope","messages":[]}}` + "\n")
+	code, f := upload(t, h, secret, in.String())
+	if code != 200 || f["purpose"] != "batch" {
+		t.Fatalf("upload: %d %v", code, f)
+	}
+	code, b, raw := call(t, h, secret, http.MethodPost, "/v1/batches", map[string]any{
+		"input_file_id": f["id"], "endpoint": "/v1/chat/completions", "completion_window": "24h",
+		"metadata": map[string]string{"job": "nightly"}})
+	if code != 200 || b["status"] != "validating" {
+		t.Fatalf("create: %d %s", code, raw)
+	}
+	b = waitBatch(t, h, secret, b["id"].(string))
+	counts := b["request_counts"].(map[string]any)
+	if b["status"] != "completed" || counts["total"] != 6.0 || counts["completed"] != 5.0 || counts["failed"] != 1.0 {
+		t.Fatalf("ended %v", b)
+	}
+	if e.calls.Load() != 5 {
+		t.Errorf("the engine served %d", e.calls.Load())
+	}
+	_, _, out := call(t, h, secret, http.MethodGet, "/v1/files/"+b["output_file_id"].(string)+"/content", nil)
+	lines := strings.Split(strings.TrimSpace(out), "\n")
+	if len(lines) != 5 || !strings.Contains(lines[0], `"custom_id":"r`) || !strings.Contains(lines[0], `"status_code":200`) {
+		t.Errorf("output:\n%s", out)
+	}
+	_, _, errs := call(t, h, secret, http.MethodGet, "/v1/files/"+b["error_file_id"].(string)+"/content", nil)
+	if !strings.Contains(errs, `"custom_id":"bad"`) {
+		t.Errorf("errors:\n%s", errs)
+	}
+	// Charged like any request, and findable by the batch.
+	var rid string
+	for _, l := range lines {
+		var o struct {
+			Response struct {
+				RequestID string `json:"request_id"`
+			} `json:"response"`
+		}
+		_ = json.Unmarshal([]byte(l), &o)
+		rid = o.Response.RequestID
+	}
+	deadline := time.Now().Add(5 * time.Second)
+	for {
+		u, ok, _ := rt.store.UsageByRequest(t.Context(), rid)
+		if ok {
+			if u.Tags["batch"] != b["id"] || u.CostMicros == 0 {
+				t.Errorf("usage %+v", u)
+			}
+			break
+		}
+		if time.Now().After(deadline) {
+			t.Fatal("a batch request left no usage")
+		}
+		time.Sleep(20 * time.Millisecond)
+	}
+	_, list, _ := call(t, h, secret, http.MethodGet, "/v1/batches", nil)
+	if d := list["data"].([]any); len(d) != 1 {
+		t.Errorf("listed %v", list)
+	}
+}
+
+func TestABatchWithBadLinesFailsAndSaysWhich(t *testing.T) {
+	e := newFakeEngine(t, "qwen2.5-14b-instruct")
+	rt, secret := pricedRouter(t, e.srv.URL)
+	h := rt.Handler()
+	_, f := upload(t, h, secret, `{"custom_id":"a","method":"POST","url":"/v1/embeddings","body":{"model":"q14"}}
+not json
+{"custom_id":"a","method":"POST","url":"/v1/chat/completions","body":{"model":"q14"}}
+`)
+	_, b, _ := call(t, h, secret, http.MethodPost, "/v1/batches", map[string]any{
+		"input_file_id": f["id"], "endpoint": "/v1/chat/completions", "completion_window": "24h"})
+	b = waitBatch(t, h, secret, b["id"].(string))
+	j, _ := json.Marshal(b["errors"])
+	if b["status"] != "failed" || !strings.Contains(string(j), "mismatched_endpoint") || !strings.Contains(string(j), "invalid_json_line") {
+		t.Errorf("%v %s", b["status"], j)
+	}
+	if e.calls.Load() != 0 {
+		t.Error("a batch that failed validation was served")
+	}
+}
+
+func TestBatchesAndFilesAreTheirOwners(t *testing.T) {
+	e := newFakeEngine(t, "qwen2.5-14b-instruct")
+	rt, secret := pricedRouter(t, e.srv.URL)
+	h := rt.Handler()
+	_, f := upload(t, h, secret, `{"custom_id":"a","method":"POST","url":"/v1/chat/completions","body":{"model":"q14"}}`)
+
+	// Another project's key sees none of it.
+	org, _ := rt.store.CreateOrg(t.Context(), "other")
+	team, _ := rt.store.CreateTeam(t.Context(), org, "t")
+	project, _ := rt.store.CreateProject(t.Context(), team, "p")
+	other := store.KeyPrefix + strings.Repeat("b", 43)
+	sum := sha256.Sum256([]byte(other))
+	if err := rt.store.CreateKey(t.Context(), store.Key{ID: "key-2", Hash: sum[:], Prefix: "bbbb", Name: "other",
+		ProjectID: project, CreatedAt: time.Now()}); err != nil {
+		t.Fatal(err)
+	}
+	if code, _, _ := call(t, h, other, http.MethodGet, "/v1/files/"+f["id"].(string), nil); code != 404 {
+		t.Errorf("another project read a file: %d", code)
+	}
+	if code, _, _ := call(t, h, other, http.MethodPost, "/v1/batches", map[string]any{
+		"input_file_id": f["id"], "endpoint": "/v1/chat/completions", "completion_window": "24h"}); code != 400 {
+		t.Errorf("another project batched a file: %d", code)
+	}
+	if code, _, _ := call(t, h, secret, http.MethodDelete, "/v1/files/"+f["id"].(string), nil); code != 200 {
+		t.Errorf("delete: %d", code)
+	}
+}
+
+func TestABatchPicksUpWhereItStoppedAndCanBeCancelled(t *testing.T) {
+	e := newFakeEngine(t, "qwen2.5-14b-instruct")
+	rt, secret := pricedRouter(t, e.srv.URL)
+	h := rt.Handler()
+	var in strings.Builder
+	for i := range 4 {
+		fmt.Fprintf(&in, `{"custom_id":"r%d","method":"POST","url":"/v1/chat/completions","body":{"model":"q14","messages":[]}}`+"\n", i)
+	}
+	_, f := upload(t, h, secret, in.String())
+
+	// As a gateway that died after serving the first line left it.
+	now := time.Now()
+	b := store.Batch{ID: "batch_resumed", Owner: "project:" + mustProjectOf(t, rt, "key-1"), KeyID: "key-1",
+		Endpoint: "/v1/chat/completions", InputFileID: f["id"].(string), CompletionWindow: "24h",
+		Status: store.BatchInProgress, CreatedAt: now, ExpiresAt: now.Add(24 * time.Hour)}
+	if err := rt.store.PutBatch(t.Context(), b); err != nil {
+		t.Fatal(err)
+	}
+	b.Total, b.Completed, b.InProgressAt = 4, 1, now
+	_ = rt.store.UpdateBatch(t.Context(), b)
+	_ = rt.store.PutBatchResult(t.Context(), b.ID, store.BatchResult{Line: 0, OK: true,
+		Data: `{"id":"batch_req_x","custom_id":"r0","response":{"status_code":200},"error":null}`})
+	rt.wakeBatches()
+	got := waitBatch(t, h, secret, b.ID)
+	if c := got["request_counts"].(map[string]any); got["status"] != "completed" || c["completed"] != 4.0 {
+		t.Fatalf("%v", got)
+	}
+	if e.calls.Load() != 3 {
+		t.Errorf("served %d; the line kept already was served again", e.calls.Load())
+	}
+
+	// Cancelled before it is served: nothing is sent.
+	b2 := b
+	b2.ID, b2.Status = "batch_cancelled", store.BatchValidating
+	if err := rt.store.PutBatch(t.Context(), b2); err != nil {
+		t.Fatal(err)
+	}
+	_, _ = rt.store.CancelBatch(t.Context(), b2.ID, time.Now())
+	rt.wakeBatches()
+	if got := waitBatch(t, h, secret, b2.ID); got["status"] != "cancelled" {
+		t.Errorf("%v", got)
+	}
+	if e.calls.Load() != 3 {
+		t.Errorf("a cancelled batch was served: %d", e.calls.Load())
+	}
+}
+
+func mustProjectOf(t *testing.T, rt *Router, keyID string) string {
+	t.Helper()
+	k, err := rt.store.KeyByID(t.Context(), keyID)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return k.ProjectID
+}
diff --git a/internal/router/batchworker.go b/internal/router/batchworker.go
new file mode 100644
index 0000000..1ba0771
--- /dev/null
+++ b/internal/router/batchworker.go
@@ -0,0 +1,373 @@
+package router
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"os"
+	"strconv"
+	"sync"
+	"time"
+
+	"gitea.mynodes.xyz/ilker/llmgw/internal/auth"
+	"gitea.mynodes.xyz/ilker/llmgw/internal/store"
+)
+
+// The worker that serves batches. Any gateway on the store may run one: a
+// batch is worked on by whichever holds its lease, and each finished line
+// is kept as it is served, so another picks up where one stopped.
+
+const (
+	batchLease = 2 * time.Minute
+	batchPoll  = 5 * time.Second
+)
+
+// wakeBatches has the worker look for work now rather than at its next poll.
+func (r *Router) wakeBatches() {
+	select {
+	case r.batchWake <- struct{}{}:
+	default:
+	}
+}
+
+func (r *Router) runBatches(ctx context.Context) {
+	host, _ := os.Hostname()
+	owner := fmt.Sprintf("%s:%d:%s", host, os.Getpid(), newID(""))
+	t := time.NewTicker(batchPoll)
+	defer t.Stop()
+	for {
+		for {
+			now := time.Now()
+			b, ok, err := r.store.ClaimBatch(ctx, owner, now, now.Add(batchLease))
+			if err != nil {
+				if ctx.Err() == nil {
+					r.log.Warn("could not look for batches to serve", "err", err)
+				}
+				break
+			}
+			if !ok {
+				break
+			}
+			r.workBatch(ctx, owner, b)
+		}
+		if _, _, _, days := r.batchCfg(); days > 0 {
+			if n, err := r.store.DeleteExpiredFiles(ctx, time.Now()); err == nil && n > 0 {
+				r.log.Info("batch files past their retention deleted", "files", n)
+			}
+		}
+		select {
+		case <-ctx.Done():
+			return
+		case <-t.C:
+		case <-r.batchWake:
+		}
+	}
+}
+
+// workBatch takes one batch as far as it goes: validated, served, written.
+func (r *Router) workBatch(ctx context.Context, owner string, b store.Batch) {
+	bctx, stop := context.WithCancel(ctx)
+	defer stop()
+	defer func() { _ = r.store.ReleaseBatch(context.WithoutCancel(ctx), b.ID, owner) }()
+	// The lease kept while working; lost, the work stops.
+	go func() {
+		t := time.NewTicker(batchLease / 4)
+		defer t.Stop()
+		for {
+			select {
+			case <-bctx.Done():
+				return
+			case <-t.C:
+				if held, err := r.store.RenewBatchLease(bctx, b.ID, owner, time.Now().Add(batchLease)); err == nil && !held {
+					stop()
+					return
+				}
+			}
+		}
+	}()
+	log := r.log.With("batch", b.ID)
+	if err := r.serveBatch(bctx, &b); err != nil && bctx.Err() == nil {
+		log.Warn("a batch stopped with an error; it is picked up again", "err", err)
+	}
+}
+
+func (r *Router) serveBatch(ctx context.Context, b *store.Batch) error {
+	content, err := r.store.FileContent(ctx, b.InputFileID)
+	if err != nil && !errors.Is(err, store.ErrNotFound) {
+		return err
+	}
+	_, maxLines, concurrency, _ := r.batchCfg()
+	lines, errs := parseBatchInput(content, b.Endpoint, maxLines)
+	if errors.Is(err, store.ErrNotFound) {
+		errs = []lineError{{Code: "file_not_found", Message: "the input file was deleted"}}
+	}
+
+	if b.Status == store.BatchValidating {
+		if len(errs) > 0 {
+			ej, _ := json.Marshal(map[string]any{"object": "list", "data": errs})
+			b.Status, b.FailedAt, b.Errors = store.BatchFailed, time.Now(), string(ej)
+			return r.store.UpdateBatch(ctx, *b)
+		}
+		b.Status, b.Total, b.InProgressAt = store.BatchInProgress, len(lines), time.Now()
+		if err := r.store.UpdateBatch(ctx, *b); err != nil {
+			return err
+		}
+	}
+
+	if b.Status == store.BatchInProgress {
+		end, err := r.serveLines(ctx, b, lines, concurrency)
+		if err != nil {
+			return err
+		}
+		switch end {
+		case store.BatchCancelling, store.BatchExpired:
+			b.Status = end
+		default:
+			b.Status, b.FinalizingAt = store.BatchFinalizing, time.Now()
+			if err := r.store.UpdateBatch(ctx, *b); err != nil {
+				return err
+			}
+		}
+	}
+
+	// Finalizing, cancelling or expired: what was served is written out.
+	return r.finishBatch(ctx, b, lines)
+}
+
+// serveLines serves the lines not yet served, a few at a time, and says why
+// it stopped: "" when every line is served.
+func (r *Router) serveLines(ctx context.Context, b *store.Batch, lines []batchLine, concurrency int) (string, error) {
+	done, err := r.store.BatchResults(ctx, b.ID)
+	if err != nil {
+		return "", err
+	}
+	served := map[int]bool{}
+	for _, d := range done {
+		served[d.Line] = true
+	}
+	p, perr := r.batchPrincipalOf(ctx, b.KeyID)
+
+	var mu sync.Mutex
+	stopWith := ""
+	lastCheck := time.Now()
+	sem := make(chan struct{}, concurrency)
+	var wg sync.WaitGroup
+	for i, l := range lines {
+		if served[i] {
+			continue
+		}
+		mu.Lock()
+		stopped := stopWith != ""
+		mu.Unlock()
+		if stopped || ctx.Err() != nil {
+			break
+		}
+		// Asked to stop, or out of time: looked at now and then, not per line.
+		if time.Since(lastCheck) > 2*time.Second {
+			lastCheck = time.Now()
+			if cur, err := r.store.BatchByID(ctx, b.ID); err == nil && cur.Status == store.BatchCancelling {
+				mu.Lock()
+				stopWith = store.BatchCancelling
+				mu.Unlock()
+				break
+			}
+			if time.Now().After(b.ExpiresAt) {
+				mu.Lock()
+				stopWith = store.BatchExpired
+				mu.Unlock()
+				break
+			}
+		}
+		sem <- struct{}{}
+		wg.Add(1)
+		go func(i int, l batchLine) {
+			defer wg.Done()
+			defer func() { <-sem }()
+			res := r.serveLine(ctx, b, p, perr, l)
+			if ctx.Err() != nil {
+				return
+			}
+			if err := r.store.PutBatchResult(ctx, b.ID, res.withLine(i)); err != nil {
+				r.log.Warn("a batch's answer could not be kept", "batch", b.ID, "err", err)
+				return
+			}
+			mu.Lock()
+			if res.OK {
+				b.Completed++
+			} else {
+				b.Failed++
+			}
+			_ = r.store.UpdateBatch(ctx, *b)
+			mu.Unlock()
+		}(i, l)
+	}
+	wg.Wait()
+	if ctx.Err() != nil {
+		return "", ctx.Err()
+	}
+	if stopWith == "" {
+		// Counted from what is kept, which is the truth after a restart.
+		rs, err := r.store.BatchResults(ctx, b.ID)
+		if err != nil {
+			return "", err
+		}
+		if len(rs) < len(lines) {
+			return "", fmt.Errorf("%d of %d lines served", len(rs), len(lines))
+		}
+	}
+	return stopWith, nil
+}
+
+// batchPrincipalOf is the key a batch was made with, as it stands now: a key
+// revoked since serves no more of it.
+func (r *Router) batchPrincipalOf(ctx context.Context, keyID string) (auth.Principal, error) {
+	k, err := r.store.KeyByID(ctx, keyID)
+	if err != nil {
+		return auth.Principal{}, err
+	}
+	switch {
+	case !k.RevokedAt.IsZero():
+		return auth.Principal{}, auth.ErrRevoked
+	case !k.ExpiresAt.IsZero() && time.Now().After(k.ExpiresAt):
+		return auth.Principal{}, auth.ErrExpired
+	}
+	eff, err := r.store.Resolve(ctx, k.ID)
+	if err != nil {
+		return auth.Principal{}, err
+	}
+	return auth.Principal{
+		KeyID: k.ID, KeyPrefix: k.Prefix, UserID: eff.UserID, ProjectID: eff.ProjectID,
+		TeamID: eff.TeamID, OrgID: eff.OrgID,
+		Band: r.batchBand(), RoutingProfile: eff.RoutingProfile, Limits: eff,
+	}, nil
+}
+
+// batchBand is the lowest admission band: a batch waits behind everyone.
+func (r *Router) batchBand() string {
+	band, prio := "", 0
+	for _, b := range r.cfg.Admission.Bands {
+		if band == "" || b.Priority < prio {
+			band, prio = b.Name, b.Priority
+		}
+	}
+	return band
+}
+
+// lineResult is a served line as it is kept.
+type lineResult struct {
+	OK   bool
+	Data string
+}
+
+func (l lineResult) withLine(i int) store.BatchResult {
+	return store.BatchResult{Line: i, OK: l.OK, Data: l.Data}
+}
+
+// serveLine sends one request the way a client's is sent — limits,
+// accounting, guardrails, admission in the lowest band — and keeps its
+// answer in OpenAI's batch output form. A limit that lifts with time is
+// waited out; one that does not fails the line.
+func (r *Router) serveLine(ctx context.Context, b *store.Batch, p auth.Principal, perr error, l batchLine) lineResult {
+	id := newID("batch_req_")
+	out := map[string]any{"id": id, "custom_id": l.CustomID, "response": nil, "error": nil}
+	fail := func(code, msg string) lineResult {
+		out["error"] = map[string]string{"code": code, "message": msg}
+		j, _ := json.Marshal(out)
+		return lineResult{Data: string(j)}
+	}
+	if perr != nil {
+		return fail("key_unusable", "the key this batch was made with can no longer be used: "+perr.Error())
+	}
+	body := withoutField(l.Body, "stream")
+	handler := r.handleInference(b.Endpoint)
+	for attempt := 1; ; attempt++ {
+		hreq, err := http.NewRequestWithContext(auth.WithPrincipal(ctx, p), http.MethodPost, b.Endpoint, bytes.NewReader(body))
+		if err != nil {
+			return fail("invalid_request", err.Error())
+		}
+		hreq.Header.Set("Content-Type", "application/json")
+		hreq.Header.Set("X-Request-Id", id)
+		hreq.Header.Set(tagsHeader, "batch="+b.ID)
+		w := &bufferWriter{header: http.Header{}}
+		handler(w, hreq)
+		status := w.status
+		if status == 0 {
+			status = http.StatusOK
+		}
+		// Waited out: a rate limit, a model loading, a queue full. Not a
+		// spent budget, which says no Retry-After because waiting does not
+		// help, and not past the batch's time.
+		if wait := w.header.Get("Retry-After"); wait != "" && (status == http.StatusTooManyRequests || status >= 500) &&
+			time.Now().Before(b.ExpiresAt) && attempt < 1000 {
+			secs, _ := strconv.Atoi(wait)
+			select {
+			case <-ctx.Done():
+				return fail("cancelled", "the gateway stopped")
+			case <-time.After(time.Duration(max(secs, 1)) * time.Second):
+			}
+			continue
+		}
+		var parsed any = json.RawMessage(bytes.TrimSpace(w.buf.Bytes()))
+		if !json.Valid(w.buf.Bytes()) {
+			parsed = w.buf.String()
+		}
+		out["response"] = map[string]any{"status_code": status, "request_id": id, "body": parsed}
+		j, _ := json.Marshal(out)
+		return lineResult{OK: status < 300, Data: string(j)}
+	}
+}
+
+// finishBatch writes what was served — answers to one file, failures to
+// another — and ends the batch: completed, cancelled or expired.
+func (r *Router) finishBatch(ctx context.Context, b *store.Batch, lines []batchLine) error {
+	rs, err := r.store.BatchResults(ctx, b.ID)
+	if err != nil {
+		return err
+	}
+	var okBuf, errBuf bytes.Buffer
+	b.Completed, b.Failed = 0, 0
+	for _, res := range rs {
+		if res.OK {
+			okBuf.WriteString(res.Data + "\n")
+			b.Completed++
+		} else {
+			errBuf.WriteString(res.Data + "\n")
+			b.Failed++
+		}
+	}
+	_, _, _, days := r.batchCfg()
+	now := time.Now()
+	keep := func(buf *bytes.Buffer, name string) (string, error) {
+		if buf.Len() == 0 {
+			return "", nil
+		}
+		f := store.File{ID: newID("file-"), Owner: b.Owner, Purpose: purposeBatchOutput,
+			Filename: b.ID + "_" + name + ".jsonl", CreatedAt: now, ExpiresAt: now.AddDate(0, 0, days)}
+		return f.ID, r.store.PutFile(ctx, f, buf.Bytes())
+	}
+	if b.OutputFileID == "" {
+		if b.OutputFileID, err = keep(&okBuf, "output"); err != nil {
+			return err
+		}
+	}
+	if b.ErrorFileID == "" {
+		if b.ErrorFileID, err = keep(&errBuf, "error"); err != nil {
+			return err
+		}
+	}
+	switch b.Status {
+	case store.BatchCancelling:
+		b.Status, b.CancelledAt = store.BatchCancelled, now
+	case store.BatchExpired:
+		b.ExpiredAt = now
+	default:
+		b.Status, b.CompletedAt = store.BatchCompleted, now
+	}
+	if err := r.store.UpdateBatch(ctx, *b); err != nil {
+		return err
+	}
+	return r.store.DeleteBatchResults(ctx, b.ID)
+}
diff --git a/internal/router/files.go b/internal/router/files.go
new file mode 100644
index 0000000..f429229
--- /dev/null
+++ b/internal/router/files.go
@@ -0,0 +1,207 @@
+package router
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+
+	"gitea.mynodes.xyz/ilker/llmgw/internal/auth"
+	"gitea.mynodes.xyz/ilker/llmgw/internal/guard"
+	"gitea.mynodes.xyz/ilker/llmgw/internal/store"
+)
+
+// The Files API, as far as batches need it: a client uploads a file of
+// requests, and reads back the files a batch writes.
+
+const (
+	purposeBatch       = "batch"
+	purposeBatchOutput = "batch_output"
+)
+
+func newID(prefix string) string {
+	var b [12]byte
+	_, _ = rand.Read(b[:])
+	return prefix + hex.EncodeToString(b[:])
+}
+
+// ownerOf is who a file or a batch belongs to: the key's project, so every
+// key of it sees them, or the person for a personal key.
+func ownerOf(p auth.Principal) string {
+	switch {
+	case p.ProjectID != "":
+		return "project:" + p.ProjectID
+	case p.UserID != "":
+		return "user:" + p.UserID
+	}
+	return "key:" + p.KeyID
+}
+
+// batchPrincipal is the caller, or a refusal when there is no store to keep
+// files and batches in.
+func (r *Router) batchPrincipal(w http.ResponseWriter, req *http.Request) (auth.Principal, bool) {
+	p, ok := auth.FromContext(req.Context())
+	if !ok || r.store == nil {
+		writeError(w, http.StatusNotImplemented, "invalid_request_error",
+			"files and batches need authentication and the store, which this gateway runs without")
+		return auth.Principal{}, false
+	}
+	// A batch's files are prompts and answers kept: not under a policy
+	// that keeps nothing.
+	if r.noStore(guard.Subject{KeyID: p.KeyID, UserID: p.UserID, ProjectID: p.ProjectID,
+		TeamID: p.TeamID, OrgID: p.OrgID, Path: req.URL.Path}) {
+		writeError(w, http.StatusForbidden, "invalid_request_error",
+			"the gateway's policy for this caller keeps nothing, and a batch is prompts and answers kept")
+		return auth.Principal{}, false
+	}
+	return p, true
+}
+
+func (r *Router) batchCfg() (maxBytes int64, maxLines, concurrency, retainDays int) {
+	b := r.cfg.Batch
+	maxBytes, maxLines, concurrency, retainDays = b.MaxFileBytes, b.MaxLines, b.Concurrency, b.RetainDays
+	if maxBytes <= 0 {
+		maxBytes = 100 << 20
+	}
+	if maxLines <= 0 {
+		maxLines = 50000
+	}
+	if concurrency <= 0 {
+		concurrency = 4
+	}
+	if retainDays <= 0 {
+		retainDays = 30
+	}
+	return
+}
+
+func fileJSON(f store.File) map[string]any {
+	out := map[string]any{"id": f.ID, "object": "file", "bytes": f.Bytes, "created_at": f.CreatedAt.Unix(),
+		"filename": f.Filename, "purpose": f.Purpose, "status": "processed"}
+	if !f.ExpiresAt.IsZero() {
+		out["expires_at"] = f.ExpiresAt.Unix()
+	}
+	return out
+}
+
+func (r *Router) handleUploadFile(w http.ResponseWriter, req *http.Request) {
+	p, ok := r.batchPrincipal(w, req)
+	if !ok {
+		return
+	}
+	maxBytes, _, _, _ := r.batchCfg()
+	req.Body = http.MaxBytesReader(w, req.Body, maxBytes+1<<20)
+	if err := req.ParseMultipartForm(32 << 20); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid_request_error",
+			fmt.Sprintf("a multipart form with purpose and file, at most %d MB: %v", maxBytes>>20, err))
+		return
+	}
+	if purpose := req.FormValue("purpose"); purpose != purposeBatch {
+		writeError(w, http.StatusBadRequest, "invalid_request_error",
+			fmt.Sprintf("purpose %q: this gateway keeps files for batches only (purpose batch)", purpose))
+		return
+	}
+	file, header, err := req.FormFile("file")
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid_request_error", "no file in the form: "+err.Error())
+		return
+	}
+	defer file.Close()
+	content, err := io.ReadAll(io.LimitReader(file, maxBytes+1))
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid_request_error", err.Error())
+		return
+	}
+	if int64(len(content)) > maxBytes {
+		writeError(w, http.StatusRequestEntityTooLarge, "invalid_request_error",
+			fmt.Sprintf("the file is larger than %d MB", maxBytes>>20))
+		return
+	}
+	f := store.File{ID: newID("file-"), Owner: ownerOf(p), Purpose: purposeBatch,
+		Filename: header.Filename, Bytes: int64(len(content)), CreatedAt: time.Now()}
+	if err := r.store.PutFile(req.Context(), f, content); err != nil {
+		writeError(w, http.StatusInternalServerError, "server_error", err.Error())
+		return
+	}
+	writeJSON(w, http.StatusOK, fileJSON(f))
+}
+
+// ownedFile is a file the caller owns, or a 404 said.
+func (r *Router) ownedFile(w http.ResponseWriter, req *http.Request, p auth.Principal) (store.File, bool) {
+	f, err := r.store.FileByID(req.Context(), req.PathValue("id"))
+	if errors.Is(err, store.ErrNotFound) || err == nil && f.Owner != ownerOf(p) {
+		writeErrorCode(w, http.StatusNotFound, "invalid_request_error", "file_not_found",
+			fmt.Sprintf("no file %q", req.PathValue("id")))
+		return store.File{}, false
+	}
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "server_error", err.Error())
+		return store.File{}, false
+	}
+	return f, true
+}
+
+func (r *Router) handleListFiles(w http.ResponseWriter, req *http.Request) {
+	p, ok := r.batchPrincipal(w, req)
+	if !ok {
+		return
+	}
+	fs, err := r.store.Files(req.Context(), ownerOf(p), req.URL.Query().Get("purpose"), 0)
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "server_error", err.Error())
+		return
+	}
+	data := make([]map[string]any, 0, len(fs))
+	for _, f := range fs {
+		data = append(data, fileJSON(f))
+	}
+	writeJSON(w, http.StatusOK, map[string]any{"object": "list", "data": data})
+}
+
+func (r *Router) handleGetFile(w http.ResponseWriter, req *http.Request) {
+	p, ok := r.batchPrincipal(w, req)
+	if !ok {
+		return
+	}
+	if f, ok := r.ownedFile(w, req, p); ok {
+		writeJSON(w, http.StatusOK, fileJSON(f))
+	}
+}
+
+func (r *Router) handleFileContent(w http.ResponseWriter, req *http.Request) {
+	p, ok := r.batchPrincipal(w, req)
+	if !ok {
+		return
+	}
+	f, ok := r.ownedFile(w, req, p)
+	if !ok {
+		return
+	}
+	b, err := r.store.FileContent(req.Context(), f.ID)
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "server_error", err.Error())
+		return
+	}
+	w.Header().Set("Content-Type", "application/octet-stream")
+	w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=%q", f.Filename))
+	_, _ = w.Write(b)
+}
+
+func (r *Router) handleDeleteFile(w http.ResponseWriter, req *http.Request) {
+	p, ok := r.batchPrincipal(w, req)
+	if !ok {
+		return
+	}
+	f, ok := r.ownedFile(w, req, p)
+	if !ok {
+		return
+	}
+	if _, err := r.store.DeleteFile(req.Context(), f.ID); err != nil {
+		writeError(w, http.StatusInternalServerError, "server_error", err.Error())
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]any{"id": f.ID, "object": "file", "deleted": true})
+}
diff --git a/internal/router/handlers.go b/internal/router/handlers.go
index 7cc1a4c..790a2bd 100644
--- a/internal/router/handlers.go
+++ b/internal/router/handlers.go
@@ -100,6 +100,16 @@ func (r *Router) Handler() http.Handler {
 	// chat completions on the way in and back on the way out.
 	mux.HandleFunc("POST /v1/responses", r.handleResponses)
 	mux.HandleFunc("GET /v1/models", r.handleModels)
+	// Files and batches: a file of requests served at the lowest priority.
+	mux.HandleFunc("POST /v1/files", r.handleUploadFile)
+	mux.HandleFunc("GET /v1/files", r.handleListFiles)
+	mux.HandleFunc("GET /v1/files/{id}", r.handleGetFile)
+	mux.HandleFunc("GET /v1/files/{id}/content", r.handleFileContent)
+	mux.HandleFunc("DELETE /v1/files/{id}", r.handleDeleteFile)
+	mux.HandleFunc("POST /v1/batches", r.handleCreateBatch)
+	mux.HandleFunc("GET /v1/batches", r.handleListBatches)
+	mux.HandleFunc("GET /v1/batches/{id}", r.handleGetBatch)
+	mux.HandleFunc("POST /v1/batches/{id}/cancel", r.handleCancelBatch)
 	// Liveness: this process is up. It says nothing about whether it can
 	// serve, which is why it is not the thing to put a load balancer on.
 	mux.HandleFunc("GET /health", func(w http.ResponseWriter, _ *http.Request) {
diff --git a/internal/router/router.go b/internal/router/router.go
index 77fa7ac..f673985 100644
--- a/internal/router/router.go
+++ b/internal/router/router.go
@@ -68,6 +68,8 @@ type Router struct {
 	// canaries counts how the two sides served.
 	canaryTargets atomic.Pointer[map[string]string]
 	canaries      canaryStats
+	// batchWake has the batch worker look for work at once.
+	batchWake chan struct{}
 
 	// extraMetrics are collectors other components publish on /metrics.
 	extraMetrics []prometheus.Collector
@@ -240,13 +242,14 @@ func New(cfg config.Server, log *slog.Logger) (*Router, error) {
 	}
 
 	r := &Router{
-		cfg:      cfg.Router,
-		landing:  cfg.Landing,
-		log:      log,
-		reg:      reg,
-		profiles: profiles,
-		prefix:   prefixScorer,
-		m:        metrics,
+		batchWake: make(chan struct{}, 1),
+		cfg:       cfg.Router,
+		landing:   cfg.Landing,
+		log:       log,
+		reg:       reg,
+		profiles:  profiles,
+		prefix:    prefixScorer,
+		m:         metrics,
 		px: proxy.New(proxy.Config{
 			DialTimeout:           cfg.Router.Timeouts.Dial,
 			ResponseHeaderTimeout: cfg.Router.Timeouts.ResponseHeader,
@@ -444,6 +447,7 @@ func (r *Router) Start(ctx context.Context) {
 		go r.pruneUsage(ctx, r.usageRetention)
 	}
 	if r.store != nil {
+		go r.runBatches(ctx)
 		go r.refreshTenants(ctx)
 		go r.purgeSessions(ctx)
 	}
diff --git a/internal/store/batches.go b/internal/store/batches.go
new file mode 100644
index 0000000..cbe37d8
--- /dev/null
+++ b/internal/store/batches.go
@@ -0,0 +1,345 @@
+package store
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"time"
+)
+
+// File is an uploaded or written file of the Files API, without its bytes.
+type File struct {
+	ID        string
+	Owner     string
+	Purpose   string
+	Filename  string
+	Bytes     int64
+	CreatedAt time.Time
+	// ExpiresAt is when it is deleted by itself; zero is never.
+	ExpiresAt time.Time
+}
+
+// PutFile keeps a file and its bytes.
+func (s *DB) PutFile(ctx context.Context, f File, content []byte) error {
+	_, err := s.db.ExecContext(ctx, `INSERT INTO files (id, owner, purpose, filename, bytes, content, created_at, expires_at)
+		VALUES (?, ?, ?, ?, ?, ?, ?, ?)`, f.ID, f.Owner, f.Purpose, f.Filename, int64(len(content)), content,
+		millis(f.CreatedAt), optMillis(f.ExpiresAt))
+	return err
+}
+
+const fileCols = `id, owner, purpose, filename, bytes, created_at, expires_at`
+
+func scanFile(sc interface{ Scan(...any) error }) (File, error) {
+	var f File
+	var created, expires int64
+	if err := sc.Scan(&f.ID, &f.Owner, &f.Purpose, &f.Filename, &f.Bytes, &created, &expires); err != nil {
+		return File{}, err
+	}
+	f.CreatedAt = time.UnixMilli(created)
+	if expires > 0 {
+		f.ExpiresAt = time.UnixMilli(expires)
+	}
+	return f, nil
+}
+
+// FileByID finds a file, ErrNotFound when there is none.
+func (s *DB) FileByID(ctx context.Context, id string) (File, error) {
+	f, err := scanFile(s.db.QueryRowContext(ctx, `SELECT `+fileCols+` FROM files WHERE id = ?`, id))
+	if errors.Is(err, sql.ErrNoRows) {
+		return File{}, ErrNotFound
+	}
+	return f, err
+}
+
+// FileContent is a file's bytes.
+func (s *DB) FileContent(ctx context.Context, id string) ([]byte, error) {
+	var b []byte
+	err := s.db.QueryRowContext(ctx, `SELECT content FROM files WHERE id = ?`, id).Scan(&b)
+	if errors.Is(err, sql.ErrNoRows) {
+		return nil, ErrNotFound
+	}
+	return b, err
+}
+
+// Files lists an owner's files, the newest first; purpose narrows it.
+func (s *DB) Files(ctx context.Context, owner, purpose string, limit int) ([]File, error) {
+	q := `SELECT ` + fileCols + ` FROM files WHERE owner = ?`
+	args := []any{owner}
+	if purpose != "" {
+		q += ` AND purpose = ?`
+		args = append(args, purpose)
+	}
+	if limit <= 0 || limit > 10000 {
+		limit = 10000
+	}
+	q += ` ORDER BY created_at DESC LIMIT ?`
+	args = append(args, limit)
+	rows, err := s.db.QueryContext(ctx, q, args...)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var out []File
+	for rows.Next() {
+		f, err := scanFile(rows)
+		if err != nil {
+			return nil, err
+		}
+		out = append(out, f)
+	}
+	return out, rows.Err()
+}
+
+// DeleteFile removes a file; false when there was none.
+func (s *DB) DeleteFile(ctx context.Context, id string) (bool, error) {
+	res, err := s.db.ExecContext(ctx, `DELETE FROM files WHERE id = ?`, id)
+	if err != nil {
+		return false, err
+	}
+	n, _ := res.RowsAffected()
+	return n > 0, nil
+}
+
+// DeleteExpiredFiles removes the files past their expiry.
+func (s *DB) DeleteExpiredFiles(ctx context.Context, now time.Time) (int64, error) {
+	res, err := s.db.ExecContext(ctx, `DELETE FROM files WHERE expires_at > 0 AND expires_at < ?`, millis(now))
+	if err != nil {
+		return 0, err
+	}
+	return res.RowsAffected()
+}
+
+// Batch is one batch of the Batch API.
+type Batch struct {
+	ID               string
+	Owner            string
+	KeyID            string
+	Endpoint         string
+	InputFileID      string
+	CompletionWindow string
+	Status           string
+	OutputFileID     string
+	ErrorFileID      string
+	Total            int
+	Completed        int
+	Failed           int
+	CreatedAt        time.Time
+	InProgressAt     time.Time
+	FinalizingAt     time.Time
+	CompletedAt      time.Time
+	FailedAt         time.Time
+	ExpiredAt        time.Time
+	CancellingAt     time.Time
+	CancelledAt      time.Time
+	ExpiresAt        time.Time
+	// Metadata is the client's, as JSON; Errors why validation failed, as
+	// JSON.
+	Metadata string
+	Errors   string
+}
+
+// Batch states, as OpenAI names them.
+const (
+	BatchValidating = "validating"
+	BatchFailed     = "failed"
+	BatchInProgress = "in_progress"
+	BatchFinalizing = "finalizing"
+	BatchCompleted  = "completed"
+	BatchExpired    = "expired"
+	BatchCancelling = "cancelling"
+	BatchCancelled  = "cancelled"
+)
+
+// BatchDone is whether a state is an end.
+func BatchDone(status string) bool {
+	switch status {
+	case BatchFailed, BatchCompleted, BatchExpired, BatchCancelled:
+		return true
+	}
+	return false
+}
+
+const batchCols = `id, owner, key_id, endpoint, input_file_id, completion_window, status, output_file_id,
+	error_file_id, total, completed, failed, created_at, in_progress_at, finalizing_at, completed_at,
+	failed_at, expired_at, cancelling_at, cancelled_at, expires_at, metadata, errors`
+
+func scanBatch(sc interface{ Scan(...any) error }) (Batch, error) {
+	var b Batch
+	var t [10]int64
+	err := sc.Scan(&b.ID, &b.Owner, &b.KeyID, &b.Endpoint, &b.InputFileID, &b.CompletionWindow, &b.Status,
+		&b.OutputFileID, &b.ErrorFileID, &b.Total, &b.Completed, &b.Failed,
+		&t[0], &t[1], &t[2], &t[3], &t[4], &t[5], &t[6], &t[7], &t[8], &b.Metadata, &b.Errors)
+	if err != nil {
+		return Batch{}, err
+	}
+	at := func(v int64) time.Time {
+		if v == 0 {
+			return time.Time{}
+		}
+		return time.UnixMilli(v)
+	}
+	b.CreatedAt, b.InProgressAt, b.FinalizingAt, b.CompletedAt = at(t[0]), at(t[1]), at(t[2]), at(t[3])
+	b.FailedAt, b.ExpiredAt, b.CancellingAt, b.CancelledAt, b.ExpiresAt = at(t[4]), at(t[5]), at(t[6]), at(t[7]), at(t[8])
+	return b, nil
+}
+
+// PutBatch records a new batch.
+func (s *DB) PutBatch(ctx context.Context, b Batch) error {
+	_, err := s.db.ExecContext(ctx, `INSERT INTO batches (id, owner, key_id, endpoint, input_file_id,
+		completion_window, status, created_at, expires_at, metadata) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
+		b.ID, b.Owner, b.KeyID, b.Endpoint, b.InputFileID, b.CompletionWindow, b.Status,
+		millis(b.CreatedAt), millis(b.ExpiresAt), b.Metadata)
+	return err
+}
+
+// UpdateBatch writes a batch's progress: its state, counts, files, times
+// and errors.
+func (s *DB) UpdateBatch(ctx context.Context, b Batch) error {
+	_, err := s.db.ExecContext(ctx, `UPDATE batches SET status = ?, output_file_id = ?, error_file_id = ?,
+		total = ?, completed = ?, failed = ?, in_progress_at = ?, finalizing_at = ?, completed_at = ?,
+		failed_at = ?, expired_at = ?, cancelling_at = ?, cancelled_at = ?, errors = ? WHERE id = ?`,
+		b.Status, b.OutputFileID, b.ErrorFileID, b.Total, b.Completed, b.Failed,
+		optMillis(b.InProgressAt), optMillis(b.FinalizingAt), optMillis(b.CompletedAt), optMillis(b.FailedAt),
+		optMillis(b.ExpiredAt), optMillis(b.CancellingAt), optMillis(b.CancelledAt), b.Errors, b.ID)
+	return err
+}
+
+// CancelBatch asks for a batch to stop: cancelling, unless it has ended
+// already. It says the batch as it stands.
+func (s *DB) CancelBatch(ctx context.Context, id string, now time.Time) (Batch, error) {
+	if _, err := s.db.ExecContext(ctx, `UPDATE batches SET status = ?, cancelling_at = ?
+		WHERE id = ? AND status IN (?, ?, ?)`, BatchCancelling, millis(now), id,
+		BatchValidating, BatchInProgress, BatchFinalizing); err != nil {
+		return Batch{}, err
+	}
+	return s.BatchByID(ctx, id)
+}
+
+// BatchByID finds a batch, ErrNotFound when there is none.
+func (s *DB) BatchByID(ctx context.Context, id string) (Batch, error) {
+	b, err := scanBatch(s.db.QueryRowContext(ctx, `SELECT `+batchCols+` FROM batches WHERE id = ?`, id))
+	if errors.Is(err, sql.ErrNoRows) {
+		return Batch{}, ErrNotFound
+	}
+	return b, err
+}
+
+// Batches lists an owner's batches, the newest first, those made before
+// the batch after when it is given.
+func (s *DB) Batches(ctx context.Context, owner, after string, limit int) ([]Batch, error) {
+	q := `SELECT ` + batchCols + ` FROM batches WHERE owner = ?`
+	args := []any{owner}
+	if after != "" {
+		q += ` AND created_at < (SELECT created_at FROM batches WHERE id = ?)`
+		args = append(args, after)
+	}
+	if limit <= 0 || limit > 100 {
+		limit = 20
+	}
+	q += ` ORDER BY created_at DESC LIMIT ?`
+	args = append(args, limit)
+	rows, err := s.db.QueryContext(ctx, q, args...)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var out []Batch
+	for rows.Next() {
+		b, err := scanBatch(rows)
+		if err != nil {
+			return nil, err
+		}
+		out = append(out, b)
+	}
+	return out, rows.Err()
+}
+
+// ClaimBatch takes the lease on one batch that has work left and that no
+// gateway holds, for owner until the time given. ok is false when there is
+// none.
+func (s *DB) ClaimBatch(ctx context.Context, owner string, now, until time.Time) (Batch, bool, error) {
+	var id string
+	err := s.db.QueryRowContext(ctx, `UPDATE batches SET lease_owner = ?, lease_until = ?
+		WHERE id = (SELECT id FROM batches WHERE status IN (?, ?, ?, ?) AND lease_until < ?
+		            ORDER BY created_at LIMIT 1)
+		  AND lease_until < ?
+		RETURNING id`, owner, millis(until), BatchValidating, BatchInProgress, BatchFinalizing, BatchCancelling,
+		millis(now), millis(now)).Scan(&id)
+	if errors.Is(err, sql.ErrNoRows) {
+		return Batch{}, false, nil
+	}
+	if err != nil {
+		return Batch{}, false, err
+	}
+	b, err := s.BatchByID(ctx, id)
+	return b, err == nil, err
+}
+
+// RenewBatchLease keeps a lease held; false when it is held no longer.
+func (s *DB) RenewBatchLease(ctx context.Context, id, owner string, until time.Time) (bool, error) {
+	res, err := s.db.ExecContext(ctx, `UPDATE batches SET lease_until = ? WHERE id = ? AND lease_owner = ?`,
+		millis(until), id, owner)
+	if err != nil {
+		return false, err
+	}
+	n, _ := res.RowsAffected()
+	return n > 0, nil
+}
+
+// ReleaseBatch gives a lease up.
+func (s *DB) ReleaseBatch(ctx context.Context, id, owner string) error {
+	_, err := s.db.ExecContext(ctx, `UPDATE batches SET lease_until = 0, lease_owner = '' WHERE id = ? AND lease_owner = ?`, id, owner)
+	return err
+}
+
+// BatchResult is one line of a batch, served.
+type BatchResult struct {
+	Line int
+	OK   bool
+	Data string
+}
+
+// PutBatchResult keeps one served line; a line kept already is left as it
+// was.
+func (s *DB) PutBatchResult(ctx context.Context, batchID string, r BatchResult) error {
+	ok := 0
+	if r.OK {
+		ok = 1
+	}
+	_, err := s.db.ExecContext(ctx, `INSERT INTO batch_results (batch_id, line, ok, data) VALUES (?, ?, ?, ?)
+		ON CONFLICT (batch_id, line) DO NOTHING`, batchID, r.Line, ok, r.Data)
+	return err
+}
+
+// BatchResults are a batch's served lines, in order.
+func (s *DB) BatchResults(ctx context.Context, batchID string) ([]BatchResult, error) {
+	rows, err := s.db.QueryContext(ctx, `SELECT line, ok, data FROM batch_results WHERE batch_id = ? ORDER BY line`, batchID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var out []BatchResult
+	for rows.Next() {
+		var r BatchResult
+		var ok int
+		if err := rows.Scan(&r.Line, &ok, &r.Data); err != nil {
+			return nil, err
+		}
+		r.OK = ok == 1
+		out = append(out, r)
+	}
+	return out, rows.Err()
+}
+
+// DeleteBatchResults forgets a batch's lines, once its files are written.
+func (s *DB) DeleteBatchResults(ctx context.Context, batchID string) error {
+	_, err := s.db.ExecContext(ctx, `DELETE FROM batch_results WHERE batch_id = ?`, batchID)
+	return err
+}
+
+func optMillis(t time.Time) int64 {
+	if t.IsZero() {
+		return 0
+	}
+	return t.UnixMilli()
+}
diff --git a/internal/store/batches_test.go b/internal/store/batches_test.go
new file mode 100644
index 0000000..45dd72d
--- /dev/null
+++ b/internal/store/batches_test.go
@@ -0,0 +1,80 @@
+package store
+
+import (
+	"errors"
+	"testing"
+	"time"
+)
+
+func TestFilesAndBatches(t *testing.T) {
+	checkFilesAndBatches(t, capacityStore(t))
+}
+
+func TestPostgresFilesAndBatches(t *testing.T) {
+	checkFilesAndBatches(t, openPG(t))
+}
+
+func checkFilesAndBatches(t *testing.T, db *DB) {
+	ctx := t.Context()
+	now := time.Now()
+	if err := db.PutFile(ctx, File{ID: "file-1", Owner: "p1", Purpose: "batch", Filename: "in.jsonl", CreatedAt: now},
+		[]byte("{\"a\":1}\n")); err != nil {
+		t.Fatal(err)
+	}
+	if err := db.PutFile(ctx, File{ID: "file-old", Owner: "p1", Purpose: "batch_output", Filename: "out.jsonl",
+		CreatedAt: now, ExpiresAt: now.Add(-time.Minute)}, []byte("x")); err != nil {
+		t.Fatal(err)
+	}
+	f, err := db.FileByID(ctx, "file-1")
+	if err != nil || f.Bytes != 8 || f.Owner != "p1" {
+		t.Fatalf("%+v %v", f, err)
+	}
+	if b, _ := db.FileContent(ctx, "file-1"); string(b) != "{\"a\":1}\n" {
+		t.Errorf("content %q", b)
+	}
+	if fs, _ := db.Files(ctx, "p1", "batch", 0); len(fs) != 1 {
+		t.Errorf("listed %v", fs)
+	}
+	if n, _ := db.DeleteExpiredFiles(ctx, now); n != 1 {
+		t.Errorf("expired %d", n)
+	}
+
+	b := Batch{ID: "batch-1", Owner: "p1", KeyID: "k", Endpoint: "/v1/chat/completions", InputFileID: "file-1",
+		CompletionWindow: "24h", Status: BatchValidating, CreatedAt: now, ExpiresAt: now.Add(24 * time.Hour)}
+	if err := db.PutBatch(ctx, b); err != nil {
+		t.Fatal(err)
+	}
+	got, ok, err := db.ClaimBatch(ctx, "gw-a", now, now.Add(time.Minute))
+	if err != nil || !ok || got.ID != "batch-1" {
+		t.Fatalf("claim: %+v %v %v", got, ok, err)
+	}
+	if _, ok, _ := db.ClaimBatch(ctx, "gw-b", now, now.Add(time.Minute)); ok {
+		t.Error("a leased batch was claimed twice")
+	}
+	if held, _ := db.RenewBatchLease(ctx, "batch-1", "gw-b", now.Add(time.Hour)); held {
+		t.Error("another gateway renewed the lease")
+	}
+	got.Status, got.Total, got.InProgressAt = BatchInProgress, 2, now
+	if err := db.UpdateBatch(ctx, got); err != nil {
+		t.Fatal(err)
+	}
+	for _, r := range []BatchResult{{Line: 1, OK: false, Data: "e"}, {Line: 0, OK: true, Data: "a"}, {Line: 0, OK: false, Data: "dup"}} {
+		if err := db.PutBatchResult(ctx, "batch-1", r); err != nil {
+			t.Fatal(err)
+		}
+	}
+	rs, _ := db.BatchResults(ctx, "batch-1")
+	if len(rs) != 2 || rs[0].Data != "a" || !rs[0].OK || rs[1].OK {
+		t.Errorf("results %+v", rs)
+	}
+	c, err := db.CancelBatch(ctx, "batch-1", now)
+	if err != nil || c.Status != BatchCancelling || c.Total != 2 || c.CancellingAt.IsZero() {
+		t.Errorf("cancel %+v %v", c, err)
+	}
+	if bs, _ := db.Batches(ctx, "p1", "", 0); len(bs) != 1 {
+		t.Errorf("listed %d", len(bs))
+	}
+	if _, err := db.BatchByID(ctx, "nope"); !errors.Is(err, ErrNotFound) {
+		t.Errorf("missing: %v", err)
+	}
+}
diff --git a/internal/store/copy.go b/internal/store/copy.go
index 8dbea3d..a7a630c 100644
--- a/internal/store/copy.go
+++ b/internal/store/copy.go
@@ -58,6 +58,9 @@ var copyOrder = []string{
 	// Who changed what is not lost by moving the store.
 	"audit_events",
 	"key_ttl",
+	"files",
+	"batches",
+	"batch_results",
 }
 
 // notCopied are tables deliberately left behind.
diff --git a/internal/store/migrations/postgres/0024_batches.sql b/internal/store/migrations/postgres/0024_batches.sql
new file mode 100644
index 0000000..60e7d24
--- /dev/null
+++ b/internal/store/migrations/postgres/0024_batches.sql
@@ -0,0 +1,56 @@
+-- Ported from the SQLite migration of the same number.
+-- The Files and Batch APIs. A file is what a client uploaded (a batch's
+-- requests) or what a batch wrote (its answers, its errors), owned by the
+-- project of the key that made it. A batch is a file of requests served one
+-- by one at the lowest priority; each finished line is kept as it is
+-- served, so a batch survives the control plane restarting under it, and
+-- the lease says which gateway is working on it.
+CREATE TABLE files (
+  id         TEXT PRIMARY KEY,
+  owner      TEXT NOT NULL,
+  purpose    TEXT NOT NULL,
+  filename   TEXT NOT NULL,
+  bytes      BIGINT NOT NULL,
+  content    BYTEA NOT NULL,
+  created_at BIGINT NOT NULL,
+  expires_at BIGINT NOT NULL DEFAULT 0
+);
+CREATE INDEX files_owner ON files (owner, created_at);
+
+CREATE TABLE batches (
+  id                TEXT PRIMARY KEY,
+  owner             TEXT NOT NULL,
+  key_id            TEXT NOT NULL,
+  endpoint          TEXT NOT NULL,
+  input_file_id     TEXT NOT NULL,
+  completion_window TEXT NOT NULL,
+  status            TEXT NOT NULL,
+  output_file_id    TEXT NOT NULL DEFAULT '',
+  error_file_id     TEXT NOT NULL DEFAULT '',
+  total             BIGINT NOT NULL DEFAULT 0,
+  completed         BIGINT NOT NULL DEFAULT 0,
+  failed            BIGINT NOT NULL DEFAULT 0,
+  created_at        BIGINT NOT NULL,
+  in_progress_at    BIGINT NOT NULL DEFAULT 0,
+  finalizing_at     BIGINT NOT NULL DEFAULT 0,
+  completed_at      BIGINT NOT NULL DEFAULT 0,
+  failed_at         BIGINT NOT NULL DEFAULT 0,
+  expired_at        BIGINT NOT NULL DEFAULT 0,
+  cancelling_at     BIGINT NOT NULL DEFAULT 0,
+  cancelled_at      BIGINT NOT NULL DEFAULT 0,
+  expires_at        BIGINT NOT NULL,
+  metadata          TEXT NOT NULL DEFAULT '',
+  errors            TEXT NOT NULL DEFAULT '',
+  lease_owner       TEXT NOT NULL DEFAULT '',
+  lease_until       BIGINT NOT NULL DEFAULT 0
+);
+CREATE INDEX batches_owner ON batches (owner, created_at);
+CREATE INDEX batches_status ON batches (status, lease_until);
+
+CREATE TABLE batch_results (
+  batch_id TEXT NOT NULL,
+  line     BIGINT NOT NULL,
+  ok       BIGINT NOT NULL,
+  data     TEXT NOT NULL,
+  PRIMARY KEY (batch_id, line)
+);
diff --git a/internal/store/migrations/sqlite/0024_batches.sql b/internal/store/migrations/sqlite/0024_batches.sql
new file mode 100644
index 0000000..1293121
--- /dev/null
+++ b/internal/store/migrations/sqlite/0024_batches.sql
@@ -0,0 +1,55 @@
+-- The Files and Batch APIs. A file is what a client uploaded (a batch's
+-- requests) or what a batch wrote (its answers, its errors), owned by the
+-- project of the key that made it. A batch is a file of requests served one
+-- by one at the lowest priority; each finished line is kept as it is
+-- served, so a batch survives the control plane restarting under it, and
+-- the lease says which gateway is working on it.
+CREATE TABLE files (
+  id         TEXT PRIMARY KEY,
+  owner      TEXT NOT NULL,
+  purpose    TEXT NOT NULL,
+  filename   TEXT NOT NULL,
+  bytes      INTEGER NOT NULL,
+  content    BLOB NOT NULL,
+  created_at INTEGER NOT NULL,
+  expires_at INTEGER NOT NULL DEFAULT 0
+);
+CREATE INDEX files_owner ON files (owner, created_at);
+
+CREATE TABLE batches (
+  id                TEXT PRIMARY KEY,
+  owner             TEXT NOT NULL,
+  key_id            TEXT NOT NULL,
+  endpoint          TEXT NOT NULL,
+  input_file_id     TEXT NOT NULL,
+  completion_window TEXT NOT NULL,
+  status            TEXT NOT NULL,
+  output_file_id    TEXT NOT NULL DEFAULT '',
+  error_file_id     TEXT NOT NULL DEFAULT '',
+  total             INTEGER NOT NULL DEFAULT 0,
+  completed         INTEGER NOT NULL DEFAULT 0,
+  failed            INTEGER NOT NULL DEFAULT 0,
+  created_at        INTEGER NOT NULL,
+  in_progress_at    INTEGER NOT NULL DEFAULT 0,
+  finalizing_at     INTEGER NOT NULL DEFAULT 0,
+  completed_at      INTEGER NOT NULL DEFAULT 0,
+  failed_at         INTEGER NOT NULL DEFAULT 0,
+  expired_at        INTEGER NOT NULL DEFAULT 0,
+  cancelling_at     INTEGER NOT NULL DEFAULT 0,
+  cancelled_at      INTEGER NOT NULL DEFAULT 0,
+  expires_at        INTEGER NOT NULL,
+  metadata          TEXT NOT NULL DEFAULT '',
+  errors            TEXT NOT NULL DEFAULT '',
+  lease_owner       TEXT NOT NULL DEFAULT '',
+  lease_until       INTEGER NOT NULL DEFAULT 0
+);
+CREATE INDEX batches_owner ON batches (owner, created_at);
+CREATE INDEX batches_status ON batches (status, lease_until);
+
+CREATE TABLE batch_results (
+  batch_id TEXT NOT NULL,
+  line     INTEGER NOT NULL,
+  ok       INTEGER NOT NULL,
+  data     TEXT NOT NULL,
+  PRIMARY KEY (batch_id, line)
+);
diff --git a/internal/store/postgres_test.go b/internal/store/postgres_test.go
index 47bf661..13e733c 100644
--- a/internal/store/postgres_test.go
+++ b/internal/store/postgres_test.go
@@ -43,7 +43,7 @@ func openPG(t *testing.T) *DB {
 		// every subtest gets a fresh file, and failed only here.
 		`TRUNCATE thread_messages, threads, memory_notes, usage, usage_5m, usage_1h, usage_1d, api_keys, memberships,
 		         key_claims, limits, models, sessions, users, projects, teams,
-		         organizations, leadership, control_planes RESTART IDENTITY CASCADE`)
+		         organizations, leadership, control_planes, files, batches, batch_results RESTART IDENTITY CASCADE`)
 	if err != nil {
 		t.Fatalf("clearing the test database: %v", err)
 	}