From 028ac573989714a63ab727fb204234ddbb55881d Mon Sep 17 00:00:00 2001
From: mika kuns <mika.kuns@fb-tuning.de>
Date: Thu, 6 Aug 2026 21:17:11 +0200
Subject: [PATCH] fix(prompts): make template token substitution
 order-independent

RenderTemplate replaced tokens one key at a time over a StringBuilder, so a
token appearing inside an already-substituted value got substituted again on a
later pass. The prompt briefs only escaped this because their callers happen to
pass "tasks" last -- reordering the dictionary or adding a fourth token would
have started rewriting user-authored task descriptions, which after the enhance
phase carry file paths and config snippets.

Single-pass regex over the template instead; unknown tokens still pass through.
---
 src/ClaudeDo.Data/PromptFiles.cs              | 17 +++++----
 tests/ClaudeDo.Data.Tests/PromptFilesTests.cs | 36 +++++++++++++++++++
 2 files changed, 46 insertions(+), 7 deletions(-)

diff --git a/src/ClaudeDo.Data/PromptFiles.cs b/src/ClaudeDo.Data/PromptFiles.cs
index b5a613fe..402e8940 100644
--- a/src/ClaudeDo.Data/PromptFiles.cs
+++ b/src/ClaudeDo.Data/PromptFiles.cs
@@ -1,6 +1,7 @@
 using System.Security.Cryptography;
 using System.Text;
 using System.Text.Json;
+using System.Text.RegularExpressions;
 
 namespace ClaudeDo.Data;
 
@@ -193,14 +194,16 @@ public static class PromptFiles
     public static string Render(PromptKind kind, IReadOnlyDictionary<string, string> values)
         => RenderTemplate(ReadOrDefault(kind), values);
 
-    /// <summary>Replace only the given {name} tokens; any other braces pass through untouched.</summary>
+    private static readonly Regex TokenPattern = new(@"\{(\w+)\}", RegexOptions.Compiled);
+
+    /// <summary>Replace only the given {name} tokens; any other braces pass through untouched.
+    /// Single pass over the template, so a token appearing inside a substituted VALUE is never
+    /// re-substituted. That matters because the values are user-authored task titles and
+    /// descriptions: a sharpened description mentioning a literal {repo} must survive verbatim,
+    /// and it must not depend on the caller happening to order its dictionary correctly.</summary>
     public static string RenderTemplate(string template, IReadOnlyDictionary<string, string> values)
-    {
-        var sb = new StringBuilder(template);
-        foreach (var (key, val) in values)
-            sb.Replace("{" + key + "}", val);
-        return sb.ToString();
-    }
+        => TokenPattern.Replace(template, m =>
+            values.TryGetValue(m.Groups[1].Value, out var val) ? val : m.Value);
 
     public static string DefaultFor(PromptKind kind) => kind switch
     {
diff --git a/tests/ClaudeDo.Data.Tests/PromptFilesTests.cs b/tests/ClaudeDo.Data.Tests/PromptFilesTests.cs
index a35d43e4..43b8f26f 100644
--- a/tests/ClaudeDo.Data.Tests/PromptFilesTests.cs
+++ b/tests/ClaudeDo.Data.Tests/PromptFilesTests.cs
@@ -22,6 +22,42 @@ public class PromptFilesTests
         Assert.Equal("## {Wochentag}, {dd.MM.yyyy} — 01.06.2026", outp);
     }
 
+    [Fact]
+    public void RenderTemplate_does_not_substitute_tokens_that_appear_inside_a_value()
+    {
+        // A sharpened task description can legitimately contain "{repo}" (a config snippet, a
+        // path placeholder). Substitution must be a single pass over the TEMPLATE, so injected
+        // values are never rescanned.
+        var outp = PromptFiles.RenderTemplate(
+            "Repo: {repo}\n\n{tasks}",
+            new Dictionary<string, string>
+            {
+                ["repo"] = "C:\\real\\repo",
+                ["tasks"] = "- Fix the {repo} placeholder in the config template",
+            });
+
+        Assert.Equal("Repo: C:\\real\\repo\n\n- Fix the {repo} placeholder in the config template", outp);
+    }
+
+    [Fact]
+    public void RenderTemplate_result_is_independent_of_dictionary_order()
+    {
+        const string template = "Scope: {scope}\nRepo: {repo}\n\n{tasks}";
+        var task = "- Document {scope} and {repo} tokens";
+
+        var tasksLast = PromptFiles.RenderTemplate(template, new Dictionary<string, string>
+        {
+            ["scope"] = "List: Bugs", ["repo"] = "C:\\repo", ["tasks"] = task,
+        });
+        var tasksFirst = PromptFiles.RenderTemplate(template, new Dictionary<string, string>
+        {
+            ["tasks"] = task, ["repo"] = "C:\\repo", ["scope"] = "List: Bugs",
+        });
+
+        Assert.Equal(tasksLast, tasksFirst);
+        Assert.Contains("- Document {scope} and {repo} tokens", tasksLast);
+    }
+
     [Fact]
     public void DefaultFor_system_mentions_blocked_marker_and_scope()
     {