Batch Analyse requests and survive opaque provider schema budgets

Analyse now classifies up to ten same-kind transactions per provider
request: the registry and history travel once per batch, so a
thousand-row backfill costs about a hundred paced requests instead of a
thousand. The answer schema appears once — an array item carrying an
enum-bound ref — because providers meter strict schemas by token cost:
duplicating registry enums per row, or bounding arrays with
minItems/maxItems that Gemini expands per element, rejects real
registries with a bare HTTP 400. Row count, duplicate refs, duplicate
tags and taxonomy bounds are all enforced server-side instead, and a
request still rejected outright halves until accepted, remembering the
working size for the run. Batch requests scale the HTTP budget by row
count, chunk failures cannot abort a run whose later rows succeeded,
and rows resolved against one snapshot share one minted merchant.

Measured on a real 165-row month over a zero-data-retention route:
165 analysed, 152 proposals, 0 errors, 17 requests, under 8 minutes.

Fresh installs default to google/gemini-3.8-flash, the model that
demonstrably honors strict structured outputs over a ZDR route. Preview
changes now carry counterparty, amount and currency, and the review
list shows the amount with a counterparty fallback for banks that leave
descriptions empty.

internal/classification/client.go

@@ -28,6 +28,32 @@ type Client struct {
 	BaseURL      string
 
 	rate atomic.Pointer[ratelimit.Controller]
+	// batchRows is the learned per-request row cap; zero means MaxBatch.
+	// Providers reject overly complex schemas outright, so ClassifyBatch
+	// halves and remembers the size that a provider actually accepts.
+	batchRows atomic.Int32
+}
+
+func (c *Client) batchCap() int {
+	if v := c.batchRows.Load(); v > 0 {
+		return int(v)
+	}
+	return MaxBatch
+}
+
+func (c *Client) shrinkBatchCap(n int) {
+	if n < 1 {
+		n = 1
+	}
+	for {
+		current := c.batchRows.Load()
+		if current > 0 && int32(n) >= current {
+			return
+		}
+		if c.batchRows.CompareAndSwap(current, int32(n)) {
+			return
+		}
+	}
 }
 
 // WithModel snapshots the configuration while sharing the original client's
@@ -218,24 +244,37 @@ func (c *Client) Classify(ctx context.Context, facts domain.Facts, data domain.D
 	if err != nil {
 		return fail("AI classification did not match the required schema")
 	}
+	result, err := resolveAnswer(answer, facts, data, candidates, clean, model, map[string]*domain.Merchant{})
+	if err != nil {
+		return failError(err)
+	}
+	return result, nil
+}
+
+// resolveAnswer maps one schema-valid provider answer onto enrichment,
+// revalidating every id against the local registry. proposed collects newly
+// minted merchants by normalized name so several rows resolved against the
+// same snapshot — a batch request — share one proposal instead of minting
+// duplicates.
+func resolveAnswer(answer answer, facts domain.Facts, data domain.Dataset, candidates candidateSet, clean func(string) string, model string, proposed map[string]*domain.Merchant) (Proposal, error) {
 	categoryID, ok := candidates.categoryIDs[answer.CategoryID]
 	if !ok {
-		return fail("AI selected a category outside the supplied registry")
+		return Proposal{}, errors.New("AI selected a category outside the supplied registry")
 	}
 	e := domain.Fallback(facts)
 	e.CategoryID = categoryID
 	for _, id := range answer.TagIDs {
 		real, ok := candidates.tagIDs[id]
 		if !ok {
-			return fail("AI selected a tag outside the supplied registry")
+			return Proposal{}, errors.New("AI selected a tag outside the supplied registry")
 		}
 		e.TagIDs = append(e.TagIDs, real)
 	}
-	var proposed *domain.Merchant
+	var minted *domain.Merchant
 	if answer.MerchantID != nil {
 		id, ok := candidates.merchantIDs[*answer.MerchantID]
 		if !ok {
-			return fail("AI selected a merchant outside the supplied registry")
+			return Proposal{}, errors.New("AI selected a merchant outside the supplied registry")
 		}
 		e.MerchantID = id
 	}
@@ -249,24 +288,31 @@ func (c *Client) Classify(ctx context.Context, facts domain.Facts, data domain.D
 			// no merchant
 		} else if existing := duplicateMerchant(name, data.Merchants); existing != nil {
 			e.MerchantID = existing.ID
+		} else if prior, ok := proposed[normalize(name)]; ok {
+			minted = prior
+			e.MerchantID = prior.ID
 		} else {
 			aliases := []string{}
 			if alias := strings.Join(strings.Fields(facts.Counterparty), " "); alias != "" {
 				aliases = append(aliases, alias)
 			}
-			proposed = &domain.Merchant{ID: domain.NewID("mer"), Name: name, Aliases: aliases, DefaultTagIDs: []string{}, UseDefaults: false}
-			e.MerchantID = proposed.ID
+			minted = &domain.Merchant{ID: domain.NewID("mer"), Name: name, Aliases: aliases, DefaultTagIDs: []string{}, UseDefaults: false}
+			proposed[normalize(name)] = minted
+			e.MerchantID = minted.ID
 		}
 	}
 	e.Classification = domain.Provenance{Source: "openrouter", Model: model, Confidence: answer.Confidence, Timestamp: time.Now().UTC().Format(time.RFC3339)}
 	validationData := data
-	if proposed != nil {
-		validationData.Merchants = append(append([]domain.Merchant{}, data.Merchants...), *proposed)
+	if len(proposed) > 0 || minted != nil {
+		validationData.Merchants = append([]domain.Merchant{}, data.Merchants...)
+		for _, m := range proposed {
+			validationData.Merchants = append(validationData.Merchants, *m)
+		}
 	}
 	if err := domain.ValidateEnrichment(validationData, facts, e); err != nil {
-		return fail("AI classification violates domain constraints")
+		return Proposal{}, errors.New("AI classification violates domain constraints")
 	}
-	return Proposal{Enrichment: e, NewMerchant: proposed}, nil
+	return Proposal{Enrichment: e, NewMerchant: minted}, nil
 }
 
 // completion is one strict structured provider request. operation names the
@@ -279,6 +325,9 @@ type completion struct {
 	schema     map[string]any
 	system     string
 	user       string
+	// timeout raises the per-request budget above the 45-second single-row
+	// default; a batch answer does one row's work per ref.
+	timeout time.Duration
 }
 
 // complete performs one private structured provider request under an already
@@ -312,6 +361,9 @@ func (c *Client) complete(ctx context.Context, gate *ratelimit.Controller, r com
 		return "", err
 	}
 	client := c.httpClient()
+	if r.timeout > client.Timeout {
+		client.Timeout = r.timeout
+	}
 	resp, err := gate.Do(ctx, func(ctx context.Context) (*http.Response, error) {
 		// Each attempt uses identical serialized bytes, credentials and controls.
 		req, err := http.NewRequestWithContext(ctx, http.MethodPost, base+"/chat/completions", bytes.NewReader(body))