refactor: replace string replacers with config regexes

MermaidID and KeyFileSlug used multi-pair strings.NewReplacer
with inline character mappings. Replaced with centralized regexes:

- regex.MermaidUnsafe: matches [/.\-] for Mermaid node IDs
- regex.SlugUnsafe: matches [/.] for journal slug generation

One regex call replaces 3-4 token references and a NewReplacer
allocation. Reduces overtokenization for agents reading the code.

Signed-off-by: Jose Alekhinne <jose@ctx.ist>

Author: josealekhine

internal/cli/dep/core/format.go

@@ -13,6 +13,7 @@ import (
 	"strings"
 
 	"github.com/ActiveMemory/ctx/internal/config/dep"
+	"github.com/ActiveMemory/ctx/internal/config/regex"
 	"github.com/ActiveMemory/ctx/internal/config/token"
 	"github.com/ActiveMemory/ctx/internal/io"
 )
@@ -25,12 +26,9 @@ import (
 // Returns:
 //   - string: Safe Mermaid node identifier
 func MermaidID(pkg string) string {
-	r := strings.NewReplacer(
-		token.Slash, token.Underscore,
-		token.Dot, token.Underscore,
-		token.Dash, token.Underscore,
+	return regex.MermaidUnsafe.ReplaceAllString(
+		pkg, token.Underscore,
 	)
-	return r.Replace(pkg)
 }
 
 // RenderMermaid produces a Mermaid graph TD definition.

internal/cli/journal/core/format/fmt.go

@@ -14,6 +14,7 @@ import (
 	"github.com/ActiveMemory/ctx/internal/config/embed/text"
 	"github.com/ActiveMemory/ctx/internal/config/file"
 	cfgFmt "github.com/ActiveMemory/ctx/internal/config/format"
+	"github.com/ActiveMemory/ctx/internal/config/regex"
 	"github.com/ActiveMemory/ctx/internal/config/token"
 )
 
@@ -46,10 +47,12 @@ func Size(bytes int64) string {
 // Returns:
 //   - string: Safe slug (e.g., "internal_config_x_go")
 func KeyFileSlug(path string) string {
-	slug := strings.ReplaceAll(path, token.Slash, token.Underscore)
-	slug = strings.ReplaceAll(slug, token.Dot, token.Underscore)
-	slug = strings.ReplaceAll(slug, token.GlobStar, token.GlobReplace)
-	return slug
+	slug := regex.SlugUnsafe.ReplaceAllString(
+		path, token.Underscore,
+	)
+	return strings.ReplaceAll(
+		slug, token.GlobStar, token.GlobReplace,
+	)
 }
 
 // SessionLink formats a Markdown list item linking to a page with a

internal/config/regex/file.go

@@ -13,5 +13,15 @@ var FileNameChar = regexp.MustCompile(`[^a-zA-Z0-9-]+`)
 
 // UUID matches a UUID (v4) anywhere in a string.
 var UUID = regexp.MustCompile(
-	`[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}`,
+	`[0-9a-f]{8}-[0-9a-f]{4}-` +
+		`[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}`,
 )
+
+// MermaidUnsafe matches characters that are invalid in
+// Mermaid node identifiers (slash, dot, hyphen).
+var MermaidUnsafe = regexp.MustCompile(`[/.\-]`)
+
+// SlugUnsafe matches characters replaced during slug
+// generation (slash, dot). Glob star (*) is handled
+// separately as it maps to a different replacement.
+var SlugUnsafe = regexp.MustCompile(`[/.]`)