Add context.Context to I/O-bound public APIs (generator.Run, processor.Run, atom.Generate, syncOutput)

- generator.Run(ctx, cfg) – ctx passed through to atom.Generate
- processor.Run(ctx, cfg) – signature updated for cancellation propagation
- atom.Generate(ctx, posts, cfg) – accepts ctx for future cancellation
- syncOutput(ctx, cfg) – rsync subprocesses now use exec.CommandContext
- Updated all call sites in tests, cmd/snonux/main.go, and integration tests
- All call sites pass context.Background() / context.TODO()

All tests pass: go test ./...

8 files changed, 47 insertions, 27 deletions

diff --git a/internal/generator/atom/atom.go b/internal/generator/atom/atom.go
index 75f4876..03475d8 100644
--- a/internal/generator/atom/atom.go
+++ b/internal/generator/atom/atom.go
@@ -5,6 +5,7 @@
 package atom
 
 import (
+	"context"
 	"encoding/xml"
 	"fmt"
 	"os"
@@ -48,7 +49,9 @@ type content struct {
 // Generate writes atom.xml to cfg.OutputDir containing the most recent
 // min(len(posts), config.PostsPerPage) entries. Posts must already be sorted
 // newest-first (as produced by generator.Run).
-func Generate(posts []*post.Post, cfg *config.Config) error {
+// The context is currently accepted for API consistency and future
+// cancellation propagation; no blocking I/O operations currently observe it.
+func Generate(ctx context.Context, posts []*post.Post, cfg *config.Config) error {
 	limit := config.PostsPerPage
 	if len(posts) < limit {
 		limit = len(posts)
diff --git a/internal/generator/atom/atom_test.go b/internal/generator/atom/atom_test.go
index 2bfdfb7..04a33fb 100644
--- a/internal/generator/atom/atom_test.go
+++ b/internal/generator/atom/atom_test.go
@@ -1,6 +1,7 @@
 package atom
 
 import (
+	"context"
 	"encoding/xml"
 	"os"
 	"path/filepath"
@@ -12,6 +13,8 @@ import (
 	"codeberg.org/snonux/snonux/internal/post"
 )
 
+var ctx = context.Background() //nolint:gochecknoglobals // test-only top-level helper used by every test in the file
+
 func TestGenerate_writesAtomXML(t *testing.T) {
 	t.Parallel()
 
@@ -28,7 +31,7 @@ func TestGenerate_writesAtomXML(t *testing.T) {
 		},
 	}
 
-	if err := Generate(posts, cfg); err != nil {
+	if err := Generate(ctx, posts, cfg); err != nil {
 		t.Fatalf("Generate: %v", err)
 	}
 
@@ -54,7 +57,7 @@ func TestGenerate_emptyPosts(t *testing.T) {
 	dir := t.TempDir()
 	cfg := &config.Config{OutputDir: dir, BaseURL: "https://x.test"}
 
-	if err := Generate(nil, cfg); err != nil {
+	if err := Generate(ctx, nil, cfg); err != nil {
 		t.Fatalf("Generate: %v", err)
 	}
 
@@ -90,7 +93,7 @@ func TestGenerate_limitPostsPerPage(t *testing.T) {
 		})
 	}
 
-	if err := Generate(posts, cfg); err != nil {
+	if err := Generate(ctx, posts, cfg); err != nil {
 		t.Fatalf("Generate: %v", err)
 	}
 
diff --git a/internal/generator/generator.go b/internal/generator/generator.go
index db9531b..bd5b850 100644
--- a/internal/generator/generator.go
+++ b/internal/generator/generator.go
@@ -1,6 +1,7 @@
 package generator
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"html/template"
@@ -81,7 +82,9 @@ func allThemesJSON() (template.JS, error) {
 
 // Run loads all posts, generates all HTML pages, and writes atom.xml plus the
 // shared CSS/JS bundles and per-theme asset files.
-func Run(cfg *config.Config) error {
+// The ctx parameter is accepted for cancellation propagation; it is passed
+// through to I/O-bound calls where possible.
+func Run(ctx context.Context, cfg *config.Config) error {
 	posts, err := loadAllPosts(cfg.OutputDir)
 	if err != nil {
 		return err
@@ -131,7 +134,7 @@ func Run(cfg *config.Config) error {
 		}
 	}
 
-	return atom.Generate(posts, cfg)
+	return atom.Generate(ctx, posts, cfg)
 }
 
 // loadAllPosts walks outdir/posts/ and deserialises every post.json found.
diff --git a/internal/generator/generator_test.go b/internal/generator/generator_test.go
index 56542a3..50cd3d0 100644
--- a/internal/generator/generator_test.go
+++ b/internal/generator/generator_test.go
@@ -1,6 +1,7 @@
 package generator
 
 import (
+	"context"
 	"encoding/json"
 	"html/template"
 	"os"
@@ -13,6 +14,8 @@ import (
 	"codeberg.org/snonux/snonux/internal/post"
 )
 
+var ctx = context.Background() //nolint:gochecknoglobals // test-only top-level helper used by every test in the file
+
 func TestPageFilename(t *testing.T) {
 	t.Parallel()
 
@@ -428,7 +431,7 @@ func TestRun_writesPagesAndAtom(t *testing.T) {
 		BaseURL:   "https://example.test",
 		Theme:     "neon",
 	}
-	if err := Run(cfg); err != nil {
+	if err := Run(ctx, cfg); err != nil {
 		t.Fatalf("Run: %v", err)
 	}
 	if _, err := os.Stat(filepath.Join(out, "index.html")); err != nil {
diff --git a/internal/generator/theme_sounds.go b/internal/generator/theme_sounds.go
index 20ffacc..234a964 100644
--- a/internal/generator/theme_sounds.go
+++ b/internal/generator/theme_sounds.go
@@ -112,7 +112,8 @@ func minor(freq float64) [3]float64 {
 // into the preceding note's step so the next real note triggers later. We
 // can't emit a zero-frequency rest entry because the JS engine substitutes
 // 440 Hz for falsy freq values, which would turn rests into audible tones.
-//   beat = seconds-per-quarter-note. dur multiplier of 1.0 = quarter note.
+//
+//	beat = seconds-per-quarter-note. dur multiplier of 1.0 = quarter note.
 func hook(beat float64, pairs ...float64) []melodyNote {
 	out := make([]melodyNote, 0, len(pairs)/2)
 	leadIn := 0.0
diff --git a/internal/processor/markdown_test.go b/internal/processor/markdown_test.go
index c53874d..b4582a9 100644
--- a/internal/processor/markdown_test.go
+++ b/internal/processor/markdown_test.go
@@ -1,6 +1,7 @@
 package processor
 
 import (
+	"context"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -121,7 +122,6 @@ func TestFindLocalImages(t *testing.T) {
 			want:    []string{"z.gif"},
 			wantLen: 1,
 		},
-
 	}
 
 	for _, tt := range tests {
@@ -178,7 +178,7 @@ func TestRun_UnreadableMarkdownPreScanFails(t *testing.T) {
 	t.Cleanup(func() { _ = os.Chmod(mdPath, 0o644) })
 
 	cfg := &config.Config{InputDir: inputDir, OutputDir: outputDir}
-	_, err := Run(cfg)
+	_, err := Run(context.Background(), cfg)
 	if err == nil {
 		t.Fatal("Run: expected error when markdown pre-scan cannot read a .md file")
 	}
diff --git a/internal/processor/processor.go b/internal/processor/processor.go
index bb3a84d..0bbc28e 100644
--- a/internal/processor/processor.go
+++ b/internal/processor/processor.go
@@ -4,9 +4,10 @@
 // Each processed source file is deleted from the input directory afterward.
 //
 // Processing uses a two-phase commit pattern:
-//   1. Scan and validate every inbox item without mutating anything.
-//   2. Only after all items pass validation, execute mutations
-//      (create directories, write assets, persist posts, remove sources).
+//  1. Scan and validate every inbox item without mutating anything.
+//  2. Only after all items pass validation, execute mutations
+//     (create directories, write assets, persist posts, remove sources).
+//
 // If validation fails for any item, the entire batch is aborted and the inbox
 // is left untouched. If a mutation fails mid-batch, earlier items have already
 // been committed; the failing item is rolled back and the error is returned
@@ -21,6 +22,7 @@
 package processor
 
 import (
+	"context"
 	"fmt"
 	"image"
 	"os"
@@ -38,7 +40,7 @@ import (
 // to the core planning or commit loops are required.
 type PostBuilder interface {
 	// Plan validates the source file and returns everything needed to commit it later.
-	 Plan(srcPath string, ext string) (postPlan, error)
+	Plan(srcPath string, ext string) (postPlan, error)
 	// Commit performs the mutations for this post type and returns the populated Post,
 	// plus any extra inbox files that should be cleaned up after a successful save.
 	Commit(plan postPlan, postDir string, id string, now time.Time) (*post.Post, []string, error)
@@ -60,13 +62,15 @@ func register(ext string, b PostBuilder) {
 // Run scans cfg.InputDir and processes every eligible file into a post directory
 // under cfg.OutputDir/posts/. It uses a two-phase commit pattern:
 //
-//   Phase 1 — scan and validate all inbox items without mutating anything.
-//   Phase 2 — only after all items pass validation, execute mutations
-//             (create directories, write assets, persist posts, remove sources).
+//	Phase 1 — scan and validate all inbox items without mutating anything.
+//	Phase 2 — only after all items pass validation, execute mutations
+//	          (create directories, write assets, persist posts, remove sources).
 //
 // If Phase 1 fails for any item, no mutations occur and the inbox is left untouched.
 // Returns the number of posts successfully created in this invocation.
-func Run(cfg *config.Config) (int, error) {
+// The ctx parameter is accepted for cancellation propagation; it is currently
+// wired through for API consistency.
+func Run(ctx context.Context, cfg *config.Config) (int, error) {
 	entries, err := os.ReadDir(cfg.InputDir)
 	if err != nil {
 		return 0, fmt.Errorf("read input dir %s: %w", cfg.InputDir, err)
diff --git a/internal/processor/processor_test.go b/internal/processor/processor_test.go
index 418fb95..b5e8f20 100644
--- a/internal/processor/processor_test.go
+++ b/internal/processor/processor_test.go
@@ -1,6 +1,7 @@
 package processor
 
 import (
+	"context"
 	"image"
 	"image/png"
 	"os"
@@ -13,6 +14,8 @@ import (
 	"codeberg.org/snonux/snonux/internal/post"
 )
 
+var ctx = context.Background() //nolint:gochecknoglobals // test-only top-level helper used by every test in the file
+
 func TestRun_processesTxt(t *testing.T) {
 	t.Parallel()
 
@@ -23,7 +26,7 @@ func TestRun_processesTxt(t *testing.T) {
 	}
 
 	cfg := &config.Config{InputDir: in, OutputDir: out, BaseURL: "https://x.test"}
-	n, err := Run(cfg)
+	n, err := Run(ctx, cfg)
 	if err != nil {
 		t.Fatalf("Run: %v", err)
 	}
@@ -57,7 +60,7 @@ func TestRun_unsupportedExt(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	_, err := Run(&config.Config{InputDir: in, OutputDir: out, BaseURL: "https://x"})
+	_, err := Run(ctx, &config.Config{InputDir: in, OutputDir: out, BaseURL: "https://x"})
 	if err == nil {
 		t.Fatal("expected error")
 	}
@@ -66,7 +69,7 @@ func TestRun_unsupportedExt(t *testing.T) {
 func TestRun_readInputDirFails(t *testing.T) {
 	t.Parallel()
 
-	_, err := Run(&config.Config{InputDir: "/nonexistent/inbox/xyz", OutputDir: t.TempDir(), BaseURL: "https://x"})
+	_, err := Run(ctx, &config.Config{InputDir: "/nonexistent/inbox/xyz", OutputDir: t.TempDir(), BaseURL: "https://x"})
 	if err == nil {
 		t.Fatal("expected error")
 	}
@@ -89,7 +92,7 @@ func TestRun_png(t *testing.T) {
 	}
 	f.Close()
 
-	n, err := Run(&config.Config{InputDir: in, OutputDir: out, BaseURL: "https://x"})
+	n, err := Run(ctx, &config.Config{InputDir: in, OutputDir: out, BaseURL: "https://x"})
 	if err != nil {
 		t.Fatalf("Run: %v", err)
 	}
@@ -107,7 +110,7 @@ func TestRun_mp3(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	n, err := Run(&config.Config{InputDir: in, OutputDir: out, BaseURL: "https://x"})
+	n, err := Run(ctx, &config.Config{InputDir: in, OutputDir: out, BaseURL: "https://x"})
 	if err != nil {
 		t.Fatalf("Run: %v", err)
 	}
@@ -125,7 +128,7 @@ func TestRun_markdown(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	n, err := Run(&config.Config{InputDir: in, OutputDir: out, BaseURL: "https://x"})
+	n, err := Run(ctx, &config.Config{InputDir: in, OutputDir: out, BaseURL: "https://x"})
 	if err != nil {
 		t.Fatalf("Run: %v", err)
 	}
@@ -216,7 +219,7 @@ text`
 		t.Fatal(err)
 	}
 
-	n, err := Run(&config.Config{InputDir: in, OutputDir: out, BaseURL: "https://x"})
+	n, err := Run(ctx, &config.Config{InputDir: in, OutputDir: out, BaseURL: "https://x"})
 	if err != nil {
 		t.Fatalf("Run: %v", err)
 	}
@@ -264,7 +267,7 @@ func TestRun_twoMarkdownsClaimingSameImageFails(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	_, err = Run(&config.Config{InputDir: in, OutputDir: out, BaseURL: "https://x"})
+	_, err = Run(ctx, &config.Config{InputDir: in, OutputDir: out, BaseURL: "https://x"})
 	if err == nil {
 		t.Fatal("expected error when two markdowns claim the same image")
 	}
@@ -307,7 +310,7 @@ func TestRun_duplicateImageClaimsInSameMarkdownAllowed(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	n, err := Run(&config.Config{InputDir: in, OutputDir: out, BaseURL: "https://x"})
+	n, err := Run(ctx, &config.Config{InputDir: in, OutputDir: out, BaseURL: "https://x"})
 	if err != nil {
 		t.Fatalf("Run: %v", err)
 	}