Upload-time duplicate detection, FTS5 query sanitization, release guard

- Reject duplicate uploads at the API boundary (HTTP 409) instead of
  silently skipping in the background worker. Checks both ingested
  documents and in-flight jobs via content_hash on the jobs table.
- Go client handles 409 with distinct messages for already-imported
  documents vs already-queued jobs.
- Sanitize FTS5 search queries by quoting each token to prevent syntax
  errors from special characters like ?, *, ", (), AND, OR, NOT.
- Add try/except safety net around FTS5 execute for edge cases.
- Add main branch guard to release.sh to prevent releasing from
  feature branches.
- Update specs and README to reflect new behaviour.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

client/cmd/add.go

@@ -1,7 +1,9 @@
 package cmd
 
 import (
+	"encoding/json"
 	"fmt"
+	"net/http"
 	"os"
 	"path/filepath"
 	"strings"
@@ -11,6 +13,21 @@ import (
 	"github.com/spf13/cobra"
 )
 
+type uploadResult struct {
+	Raw       interface{}
+	Duplicate bool
+	DocID     float64
+	JobID     float64
+	Title     string
+}
+
+func (r *uploadResult) duplicateMsg() string {
+	if r.DocID > 0 {
+		return fmt.Sprintf("Already imported: %s (doc ID: %.0f)", r.Title, r.DocID)
+	}
+	return fmt.Sprintf("Already queued: %s (job ID: %.0f)", r.Title, r.JobID)
+}
+
 var supportedExts = map[string]bool{
 	".pdf":  true,
 	".docx": true,
@@ -67,6 +84,26 @@ func runAdd(cmd *cobra.Command, args []string) error {
 			fmt.Fprintln(os.Stderr, err)
 			os.Exit(1)
 		}
+
+		if resp.StatusCode == http.StatusConflict {
+			var result interface{}
+			if err := api.DecodeJSON(resp, &result); err != nil {
+				return fmt.Errorf("failed to decode response: %w", err)
+			}
+			if output.IsJSON() {
+				output.PrintJSON(result)
+			} else {
+				if m, ok := result.(map[string]interface{}); ok {
+					if docID, ok := m["document_id"].(float64); ok {
+						fmt.Printf("Already imported: %s (doc ID: %.0f)\n", m["title"], docID)
+					} else if jobID, ok := m["job_id"].(float64); ok {
+						fmt.Printf("Already queued: %s (job ID: %.0f)\n", m["title"], jobID)
+					}
+				}
+			}
+			return nil
+		}
+
 		if err := api.CheckError(resp); err != nil {
 			fmt.Fprintln(os.Stderr, err)
 			os.Exit(1)
@@ -104,7 +141,9 @@ func runAdd(cmd *cobra.Command, args []string) error {
 		}
 
 		if output.IsJSON() {
-			output.PrintJSON([]interface{}{result})
+			output.PrintJSON([]interface{}{result.Raw})
+		} else if result.Duplicate {
+			fmt.Println(result.duplicateMsg())
 		} else {
 			fmt.Printf("Queued: %s\n", filepath.Base(path))
 		}
@@ -135,27 +174,39 @@ func runAdd(cmd *cobra.Command, args []string) error {
 	}
 
 	var results []interface{}
+	queued := 0
+	duplicates := 0
 	for _, f := range files {
 		result, err := uploadFile(client, f, tags, docType)
 		if err != nil {
 			fmt.Fprintf(os.Stderr, "Error uploading %s: %v\n", f, err)
 			continue
 		}
-		results = append(results, result)
-		if !output.IsJSON() {
-			fmt.Printf("Queued: %s\n", filepath.Base(f))
+		results = append(results, result.Raw)
+		if result.Duplicate {
+			duplicates++
+			if !output.IsJSON() {
+				fmt.Println(result.duplicateMsg())
+			}
+		} else {
+			queued++
+			if !output.IsJSON() {
+				fmt.Printf("Queued: %s\n", filepath.Base(f))
+			}
 		}
 	}
 
 	if output.IsJSON() {
 		output.PrintJSON(results)
+	} else if duplicates > 0 {
+		fmt.Printf("Queued: %d files, %d duplicates skipped\n", queued, duplicates)
 	} else {
-		fmt.Printf("Queued: %d files\n", len(results))
+		fmt.Printf("Queued: %d files\n", queued)
 	}
 	return nil
 }
 
-func uploadFile(client *api.Client, path, tags, docType string) (interface{}, error) {
+func uploadFile(client *api.Client, path, tags, docType string) (*uploadResult, error) {
 	f, err := os.Open(path)
 	if err != nil {
 		return nil, fmt.Errorf("cannot open %s: %w", path, err)
@@ -180,6 +231,29 @@ func uploadFile(client *api.Client, path, tags, docType string) (interface{}, er
 	if err != nil {
 		return nil, err
 	}
+
+	if resp.StatusCode == http.StatusConflict {
+		var raw json.RawMessage
+		if err := api.DecodeJSON(resp, &raw); err != nil {
+			return nil, fmt.Errorf("failed to decode response: %w", err)
+		}
+		var dupResp struct {
+			DocumentID float64 `json:"document_id"`
+			JobID      float64 `json:"job_id"`
+			Title      string  `json:"title"`
+		}
+		json.Unmarshal(raw, &dupResp)
+		var rawIface interface{}
+		json.Unmarshal(raw, &rawIface)
+		return &uploadResult{
+			Raw:       rawIface,
+			Duplicate: true,
+			DocID:     dupResp.DocumentID,
+			JobID:     dupResp.JobID,
+			Title:     dupResp.Title,
+		}, nil
+	}
+
 	if err := api.CheckError(resp); err != nil {
 		return nil, err
 	}
@@ -188,5 +262,5 @@ func uploadFile(client *api.Client, path, tags, docType string) (interface{}, er
 	if err := api.DecodeJSON(resp, &result); err != nil {
 		return nil, fmt.Errorf("failed to decode response: %w", err)
 	}
-	return result, nil
+	return &uploadResult{Raw: result}, nil
 }