diff --git a/headroom/cli/learn.py b/headroom/cli/learn.py
index b0c6f4bf2..f94bdb3bf 100644
--- a/headroom/cli/learn.py
+++ b/headroom/cli/learn.py
@@ -226,7 +226,13 @@ def learn(
             total_recommendations += len(recommendations)
             click.echo(f"  Recommendations: {len(recommendations)}")
 
-            result = writer.write(recommendations, proj, dry_run=not apply)
+            try:
+                result = writer.write(recommendations, proj, dry_run=not apply)
+            except OSError as e:
+                click.echo(
+                    f"  Warning: failed to write recommendations for {proj.project_path}: {e}"
+                )
+                continue
 
             for file_path, content in result.content_by_file.items():
                 click.echo(f"\n  {'[WOULD WRITE]' if result.dry_run else '[WROTE]'} {file_path}")
diff --git a/headroom/learn/plugins/claude.py b/headroom/learn/plugins/claude.py
index 1275a850f..6d5a20025 100644
--- a/headroom/learn/plugins/claude.py
+++ b/headroom/learn/plugins/claude.py
@@ -8,7 +8,7 @@ from __future__ import annotations
 import json
 import logging
 import re
-from pathlib import Path
+from pathlib import Path, PureWindowsPath
 
 from .._shared import classify_error, is_error_content
 from ..base import ConversationScanner, LearnPlugin
@@ -77,7 +77,7 @@ class ClaudeCodePlugin(LearnPlugin, ConversationScanner):
                 else:
                     project_path = Path("/" + entry.name[1:].replace("-", "/"))
 
-            name = project_path.name if project_path != Path("/") else entry.name
+            name = _project_display_name(project_path, entry.name)
 
             context_file = None
             if project_path.exists():
@@ -323,6 +323,8 @@ def _decode_project_path(escaped_name: str) -> Path | None:
             result = _greedy_path_decode(win_base, parts[2:])
             if result:
                 return result
+        if len(parts) > 1 and parts[1].lower() == "users":
+            return win_path
 
     simple = Path("/" + escaped_name[1:].replace("-", "/"))
     if simple.exists():
@@ -344,6 +346,16 @@ def _decode_project_path(escaped_name: str) -> Path | None:
     return None
 
 
+def _project_display_name(project_path: Path, fallback: str) -> str:
+    """Return a human project name for POSIX and Windows-style decoded paths."""
+    rendered = str(project_path)
+    if re.match(r"^[A-Za-z]:[\\/]", rendered):
+        return PureWindowsPath(rendered).name or fallback
+    if project_path == Path("/"):
+        return fallback
+    return project_path.name or fallback
+
+
 def _greedy_path_decode(base: Path, parts: list[str]) -> Path | None:
     """Greedily decode remaining path parts using real child directories."""
     if not parts:
diff --git a/headroom/learn/writer.py b/headroom/learn/writer.py
index 8d2168ab2..ddad3e529 100644
--- a/headroom/learn/writer.py
+++ b/headroom/learn/writer.py
@@ -153,7 +153,7 @@ def _merge_recommendations(
     """
     if not file_path.exists():
         return new_recommendations
-    prior = _parse_prior_recommendations(file_path.read_text())
+    prior = _parse_prior_recommendations(file_path.read_text(encoding="utf-8"))
     if not prior:
         return new_recommendations
     new_sections = {r.section for r in new_recommendations}
@@ -166,9 +166,9 @@ def _merge_into_file(file_path: Path, new_recommendations: list[Recommendation])
     merged = _merge_recommendations(file_path, new_recommendations)
     section = _build_section(merged)
     if file_path.exists():
-        existing = file_path.read_text()
+        existing = file_path.read_text(encoding="utf-8")
         if _MARKER_START in existing:
-            return _MARKER_PATTERN.sub(section, existing)
+            return _MARKER_PATTERN.sub(lambda _match: section, existing)
         return existing.rstrip() + "\n\n" + section + "\n"
     return section + "\n"
 
@@ -199,7 +199,7 @@ class ClaudeCodeWriter(ContextWriter):
             result.add(claude_md_path, full_content)
             if not dry_run:
                 claude_md_path.parent.mkdir(parents=True, exist_ok=True)
-                claude_md_path.write_text(full_content)
+                claude_md_path.write_text(full_content, encoding="utf-8")
 
         if memory_recs:
             memory_path = self._resolve_memory_path(project)
@@ -207,7 +207,7 @@ class ClaudeCodeWriter(ContextWriter):
             result.add(memory_path, full_content)
             if not dry_run:
                 memory_path.parent.mkdir(parents=True, exist_ok=True)
-                memory_path.write_text(full_content)
+                memory_path.write_text(full_content, encoding="utf-8")
 
         return result
 
@@ -252,7 +252,7 @@ class CodexWriter(ContextWriter):
             result.add(agents_md, full_content)
             if not dry_run:
                 agents_md.parent.mkdir(parents=True, exist_ok=True)
-                agents_md.write_text(full_content)
+                agents_md.write_text(full_content, encoding="utf-8")
 
         if memory_recs:
             instructions_md = project.memory_file or (project.data_path.parent / "instructions.md")
@@ -260,7 +260,7 @@ class CodexWriter(ContextWriter):
             result.add(instructions_md, full_content)
             if not dry_run:
                 instructions_md.parent.mkdir(parents=True, exist_ok=True)
-                instructions_md.write_text(full_content)
+                instructions_md.write_text(full_content, encoding="utf-8")
 
         return result
 
@@ -290,6 +290,6 @@ class GeminiWriter(ContextWriter):
         result.add(gemini_md, full_content)
         if not dry_run:
             gemini_md.parent.mkdir(parents=True, exist_ok=True)
-            gemini_md.write_text(full_content)
+            gemini_md.write_text(full_content, encoding="utf-8")
 
         return result
diff --git a/headroom/memory/sync_adapters/claude_code.py b/headroom/memory/sync_adapters/claude_code.py
index 6fe2f374d..2a773e0f4 100644
--- a/headroom/memory/sync_adapters/claude_code.py
+++ b/headroom/memory/sync_adapters/claude_code.py
@@ -35,6 +35,21 @@ def _sanitize_for_filename(text: str) -> str:
     return slug or "memory"
 
 
+def encode_claude_project_path(project_path: Path | str) -> str:
+    """Encode a project path the way Claude Code names project directories.
+
+    POSIX absolute paths naturally become ``-Users-me-repo``. Windows drive
+    paths should become ``-C-Users-me-repo`` rather than ``C:-Users-me-repo``.
+    """
+    rendered = str(project_path)
+    drive_match = re.match(r"^([A-Za-z]):[\\/](.*)$", rendered)
+    if drive_match:
+        drive, rest = drive_match.groups()
+        rest = rest.replace("\\", "-").replace("/", "-")
+        return f"-{drive.upper()}-{rest}" if rest else f"-{drive.upper()}"
+    return rendered.replace("/", "-").replace("\\", "-")
+
+
 def _parse_frontmatter(content: str) -> tuple[dict[str, str], str]:
     """Parse YAML frontmatter from a markdown file.
 
@@ -232,6 +247,5 @@ def get_claude_memory_dir(project_path: Path | None = None) -> Path:
         ~/.claude/projects/-<sanitized-path>/memory/
     """
     project = project_path or Path.cwd()
-    # Replace both Unix and Windows path separators (Claude Code does the same)
-    sanitized = str(project).replace("/", "-").replace("\\", "-")
+    sanitized = encode_claude_project_path(project)
     return Path.home() / ".claude" / "projects" / sanitized / "memory"
diff --git a/headroom/memory/sync_adapters/codex_agent.py b/headroom/memory/sync_adapters/codex_agent.py
index b346590ba..993ebf5a1 100644
--- a/headroom/memory/sync_adapters/codex_agent.py
+++ b/headroom/memory/sync_adapters/codex_agent.py
@@ -85,7 +85,7 @@ class CodexAdapter(AgentMemoryAdapter):
         if self._path.exists():
             content = self._path.read_text(encoding="utf-8")
             if _MARKER_START in content:
-                content = _MARKER_PATTERN.sub(section, content)
+                content = _MARKER_PATTERN.sub(lambda _match: section, content)
             else:
                 content = content.rstrip() + "\n\n" + section + "\n"
         else:
diff --git a/headroom/memory/traffic_learner.py b/headroom/memory/traffic_learner.py
index 25507de38..9f462e160 100644
--- a/headroom/memory/traffic_learner.py
+++ b/headroom/memory/traffic_learner.py
@@ -1256,7 +1256,7 @@ def _project_for_pattern(pattern: ExtractedPattern, roots: list[ProjectInfo]) ->
 
     for cand in candidates:
         for root in roots_sorted:
-            root_str = str(root.project_path).rstrip("/")
+            root_str = str(root.project_path).rstrip("/\\")
             if not root_str:
                 continue
             if (
diff --git a/headroom/memory/writers/base.py b/headroom/memory/writers/base.py
index 252cef194..367a82787 100644
--- a/headroom/memory/writers/base.py
+++ b/headroom/memory/writers/base.py
@@ -160,7 +160,7 @@ class AgentWriter(ABC):
 
         if not dry_run:
             target.parent.mkdir(parents=True, exist_ok=True)
-            target.write_text(full_content)
+            target.write_text(full_content, encoding="utf-8")
 
         return result
 
@@ -185,8 +185,8 @@ class AgentWriter(ABC):
 def _merge_section(file_path: Path, section: str) -> str:
     """Merge a marker-delimited section into an existing file."""
     if file_path.exists():
-        existing = file_path.read_text()
+        existing = file_path.read_text(encoding="utf-8")
         if MARKER_START in existing:
-            return MARKER_PATTERN.sub(section, existing)
+            return MARKER_PATTERN.sub(lambda _match: section, existing)
         return existing.rstrip() + "\n\n" + section + "\n"
     return section + "\n"
diff --git a/headroom/memory/writers/claude_writer.py b/headroom/memory/writers/claude_writer.py
index 923b296fc..44d971363 100644
--- a/headroom/memory/writers/claude_writer.py
+++ b/headroom/memory/writers/claude_writer.py
@@ -12,6 +12,7 @@ from __future__ import annotations
 from collections import defaultdict
 from pathlib import Path
 
+from headroom.memory.sync_adapters.claude_code import encode_claude_project_path
 from headroom.memory.writers.base import AgentWriter, MemoryEntry
 
 
@@ -64,8 +65,7 @@ class ClaudeCodeMemoryWriter(AgentWriter):
         project_path = self._project_path
         # Claude Code stores per-project memory at:
         # ~/.claude/projects/-<sanitized-path>/memory/MEMORY.md
-        # Replace both Unix and Windows path separators
-        sanitized = str(project_path).replace("/", "-").replace("\\", "-")
+        sanitized = encode_claude_project_path(project_path)
         claude_memory_dir = Path.home() / ".claude" / "projects" / sanitized / "memory"
         return claude_memory_dir / "MEMORY.md"
 
@@ -116,6 +116,6 @@ class ClaudeCodeMemoryWriter(AgentWriter):
 
             if not dry_run:
                 memory_dir.mkdir(parents=True, exist_ok=True)
-                (memory_dir / filename).write_text(content)
+                (memory_dir / filename).write_text(content, encoding="utf-8")
 
         return topic_files
diff --git a/headroom/memory/writers/cursor_writer.py b/headroom/memory/writers/cursor_writer.py
index 0cc0a37c3..ea77b537e 100644
--- a/headroom/memory/writers/cursor_writer.py
+++ b/headroom/memory/writers/cursor_writer.py
@@ -100,10 +100,10 @@ class CursorMemoryWriter(AgentWriter):
 
         # If file exists and has our markers, only replace marker section
         if target.exists():
-            existing = target.read_text()
+            existing = target.read_text(encoding="utf-8")
             if MARKER_START in existing:
                 section = f"{MARKER_START}\n{body}\n{MARKER_END}"
-                full_content = MARKER_PATTERN.sub(section, existing)
+                full_content = MARKER_PATTERN.sub(lambda _match: section, existing)
             else:
                 # Append our section
                 section = f"{MARKER_START}\n{body}\n{MARKER_END}"
@@ -127,6 +127,6 @@ class CursorMemoryWriter(AgentWriter):
 
         if not dry_run:
             target.parent.mkdir(parents=True, exist_ok=True)
-            target.write_text(full_content)
+            target.write_text(full_content, encoding="utf-8")
 
         return result
diff --git a/tests/test_cli_learn.py b/tests/test_cli_learn.py
index 33a64d82d..87125fab4 100644
--- a/tests/test_cli_learn.py
+++ b/tests/test_cli_learn.py
@@ -20,9 +20,12 @@ def runner() -> CliRunner:
 class FakeWriter:
     def __init__(self) -> None:
         self.calls: list[tuple[list[object], object, bool]] = []
+        self.fail_for: object | None = None
 
     def write(self, recommendations, project, dry_run: bool):  # noqa: ANN001, ANN201
         self.calls.append((recommendations, project, dry_run))
+        if project is self.fail_for:
+            raise PermissionError(f"cannot write {project.project_path}")
         return SimpleNamespace(
             dry_run=dry_run,
             content_by_file={
@@ -218,6 +221,33 @@ def test_learn_analyze_all_uses_default_workers_and_prints_summary(
     assert plugin_b.scan_calls == [(projects_b[0], 8)]
 
 
+def test_learn_analyze_all_continues_when_one_project_write_fails(
+    monkeypatch: pytest.MonkeyPatch, runner: CliRunner, tmp_path: Path
+) -> None:
+    blocked = SimpleNamespace(name="blocked", project_path=tmp_path / "blocked")
+    ok = SimpleNamespace(name="ok", project_path=tmp_path / "ok")
+    plugin = FakePlugin("claude", "Claude Code", [blocked, ok])
+    plugin.writer.fail_for = blocked
+    analyzer = FakeAnalyzer()
+
+    monkeypatch.setattr("headroom.learn.analyzer._detect_default_model", lambda: "gpt-4o")
+    monkeypatch.setattr("headroom.learn.registry.get_plugin", lambda name: plugin)
+    monkeypatch.setattr("headroom.learn.analyzer.SessionAnalyzer", lambda model=None: analyzer)
+
+    result = runner.invoke(
+        main,
+        ["learn", "--agent", "claude", "--all", "--apply"],
+        catch_exceptions=False,
+    )
+
+    assert result.exit_code == 0, result.output
+    assert "Warning: failed to write recommendations" in result.output
+    assert str(blocked.project_path) in result.output
+    assert "[WROTE]" in result.output
+    assert str(ok.project_path / "AGENTS.md") in result.output
+    assert plugin.scan_calls == [(blocked, 8), (ok, 8)]
+
+
 def test_learn_handles_empty_sessions_and_no_pattern_outputs(
     monkeypatch: pytest.MonkeyPatch, runner: CliRunner, tmp_path: Path
 ) -> None:
diff --git a/tests/test_learn/test_scanner.py b/tests/test_learn/test_scanner.py
index 48aaa003d..e35cd79ed 100644
--- a/tests/test_learn/test_scanner.py
+++ b/tests/test_learn/test_scanner.py
@@ -8,12 +8,13 @@ making it impossible to reconstruct names formed from three or more tokens.
 
 from __future__ import annotations
 
+from collections.abc import Generator
 from pathlib import Path
 from uuid import uuid4
 
 import pytest
 
-from headroom.learn.scanner import _decode_project_path, _greedy_path_decode
+from headroom.learn.scanner import ClaudeCodeScanner, _decode_project_path, _greedy_path_decode
 
 # ---------------------------------------------------------------------------
 # Helpers
@@ -191,7 +192,7 @@ class TestDecodeProjectPath:
     # ------------------------------------------------------------------
 
     @pytest.fixture()
-    def users_tmp(self, tmp_path: Path) -> Path:
+    def users_tmp(self, tmp_path: Path) -> Generator[Path, None, None]:
         """Return a temporary directory whose path starts with /Users/…
 
         On macOS the system temp dir is under /private/var, so we create a
@@ -315,10 +316,31 @@ class TestDecodeProjectPath:
 
     def test_windows_users_path(self) -> None:
         """Encoded name -C-Users-foo-project detects drive letter."""
-        import sys
-
         result = _decode_project_path("-C-Users-foo-project")
-        if sys.platform == "win32":
-            assert result is None or "Users" in str(result)
-        else:
-            assert result is None
+        assert result is not None
+        assert str(result).startswith("C:")
+        assert "Users" in str(result)
+
+    def test_windows_username_with_dot_stays_single_component(self) -> None:
+        """Windows profile names like john.doe must not decode as john/doe."""
+        result = _decode_project_path("-C-Users-john.doe-work")
+
+        assert result is not None
+        rendered = str(result)
+        assert rendered.startswith("C:")
+        assert "john.doe" in rendered
+        assert "john\\doe" not in rendered
+        assert "john/doe" not in rendered
+
+    def test_discover_windows_project_uses_leaf_name(self, tmp_path: Path) -> None:
+        """A syntactic Windows path decoded on Unix should still display the project leaf."""
+        claude_dir = tmp_path / ".claude"
+        project_dir = claude_dir / "projects" / "-C-Users-john.doe-work"
+        project_dir.mkdir(parents=True)
+        (project_dir / "session.jsonl").write_text("{}\n")
+
+        projects = ClaudeCodeScanner(claude_dir=claude_dir).discover_projects()
+
+        assert len(projects) == 1
+        assert projects[0].name == "work"
+        assert str(projects[0].project_path).startswith("C:")
diff --git a/tests/test_learn/test_writer.py b/tests/test_learn/test_writer.py
index 4b2d6d212..80b98ad40 100644
--- a/tests/test_learn/test_writer.py
+++ b/tests/test_learn/test_writer.py
@@ -7,6 +7,7 @@ from headroom.learn.writer import (
     _MARKER_END,
     _MARKER_START,
     ClaudeCodeWriter,
+    _merge_into_file,
     _parse_prior_recommendations,
     extract_marker_block,
 )
@@ -146,6 +147,33 @@ class TestClaudeCodeWriter:
         # Only one Environment section in the final block
         assert content.count("### Environment") == 1
 
+    def test_replacing_existing_block_handles_literal_backslash_escapes(self, tmp_path):
+        """LLM text with backslash escapes must not be interpreted as a regex replacement."""
+        proj = _project(tmp_path)
+        claude_md = proj.project_path / "CLAUDE.md"
+        claude_md.write_text(
+            f"# Existing\n\n{_MARKER_START}\n"
+            "## Headroom Learned Patterns\n\n"
+            "### Windows Paths\n"
+            "- stale\n\n"
+            f"{_MARKER_END}\n"
+        )
+
+        full_content = _merge_into_file(
+            claude_md,
+            [
+                _rec(
+                    RecommendationTarget.CONTEXT_FILE,
+                    "Windows Paths",
+                    r"- Keep the literal \u sequence and C:\Users\john.doe\repo path",
+                )
+            ],
+        )
+
+        assert r"\u sequence" in full_content
+        assert r"C:\Users\john.doe\repo" in full_content
+        assert "stale" not in full_content
+
     def test_memory_md_carry_forward(self, tmp_path):
         """Carry-forward also works for MEMORY.md."""
         proj = _project(tmp_path)
diff --git a/tests/test_memory/test_traffic_learner.py b/tests/test_memory/test_traffic_learner.py
index 1335d45ca..05e929268 100644
--- a/tests/test_memory/test_traffic_learner.py
+++ b/tests/test_memory/test_traffic_learner.py
@@ -521,6 +521,16 @@ class TestProjectForPattern:
         )
         assert _project_for_pattern(pattern, [proj]) is proj
 
+    def test_windows_root_with_trailing_backslash_matches_child_path(self):
+        proj = self._project(r"C:\Users\john.doe\repo\\")
+        pattern = ExtractedPattern(
+            category=PatternCategory.ERROR_RECOVERY,
+            content=r"File `C:\Users\john.doe\repo\src\main.py` does not exist.",
+            importance=0.5,
+        )
+
+        assert _project_for_pattern(pattern, [proj]) is proj
+
     def test_no_false_match_on_prefix_boundary(self):
         # /x/ab should not match a project rooted at /x/a
         proj_a = self._project("/x/a")
diff --git a/tests/test_memory/test_writers.py b/tests/test_memory/test_writers.py
index 455065cd4..9ecc58be8 100644
--- a/tests/test_memory/test_writers.py
+++ b/tests/test_memory/test_writers.py
@@ -99,6 +99,17 @@ class TestMergeSection:
         assert "# Header" in result
         assert "# Footer" in result
 
+    def test_replace_existing_markers_handles_literal_backslashes(self, tmp_path: Path):
+        existing = tmp_path / "marked.md"
+        existing.write_text(f"# Header\n\n{MARKER_START}\nold content\n{MARKER_END}\n")
+        section = f"{MARKER_START}\n- Keep C:\\Users\\john.doe\\repo and literal \\u\n{MARKER_END}"
+
+        result = _merge_section(existing, section)
+
+        assert r"C:\Users\john.doe\repo" in result
+        assert r"literal \u" in result
+        assert "old content" not in result
+
 
 # =============================================================================
 # Claude Code Writer Tests
@@ -183,6 +194,14 @@ class TestClaudeCodeWriter:
             assert filename.startswith("headroom_")
             assert "---" in content  # YAML frontmatter
 
+    def test_default_path_encodes_windows_user_with_dot(self):
+        writer = ClaudeCodeMemoryWriter(project_path=Path(r"C:\Users\john.doe\work"))
+
+        rendered = str(writer.default_path())
+        assert "-C-Users-john.doe-work" in rendered
+        assert "john-doe" not in rendered
+        assert rendered.endswith("MEMORY.md")
+
 
 # =============================================================================
 # Cursor Writer Tests
diff --git a/tests/test_memory_sync.py b/tests/test_memory_sync.py
index d801f047c..903c63915 100644
--- a/tests/test_memory_sync.py
+++ b/tests/test_memory_sync.py
@@ -30,6 +30,8 @@ from headroom.memory.sync import (
 from headroom.memory.sync_adapters.claude_code import (
     ClaudeCodeAdapter,
     _parse_frontmatter,
+    encode_claude_project_path,
+    get_claude_memory_dir,
 )
 from headroom.memory.sync_adapters.codex_agent import CodexAdapter
 
@@ -408,6 +410,17 @@ class TestClaudeCodeAdapter:
         assert fm == {}
         assert body == "Just plain content."
 
+    def test_encode_claude_project_path_windows_user_with_dot(self):
+        assert encode_claude_project_path(r"C:\Users\john.doe\work") == "-C-Users-john.doe-work"
+
+    def test_get_claude_memory_dir_uses_windows_safe_project_encoding(self):
+        memory_dir = get_claude_memory_dir(Path(r"C:\Users\john.doe\work"))
+
+        rendered = str(memory_dir)
+        assert "-C-Users-john.doe-work" in rendered
+        assert "john-doe" not in rendered
+        assert rendered.endswith("memory")
+
     @pytest.mark.asyncio
     async def test_read_memories_skips_memory_md(self, memory_dir):
         (memory_dir / "MEMORY.md").write_text("# Index\n- entry")
@@ -537,6 +550,23 @@ class TestCodexAdapter:
         assert "new fact" in content
         assert "old fact" not in content
 
+    @pytest.mark.asyncio
+    async def test_write_replaces_existing_section_with_literal_backslashes(self, agents_md):
+        agents_md.write_text(
+            "# Instructions\n\n"
+            "<!-- headroom:memory:start -->\n"
+            "## Old\n- old fact\n"
+            "<!-- headroom:memory:end -->\n"
+        )
+
+        adapter = CodexAdapter(agents_md)
+        await adapter.write_memories([{"content": r"Use C:\Users\john.doe\repo and literal \u"}])
+
+        content = agents_md.read_text()
+        assert r"C:\Users\john.doe\repo" in content
+        assert r"literal \u" in content
+        assert "old fact" not in content
+
     @pytest.mark.asyncio
     async def test_read_empty_agents_md(self, agents_md):
         agents_md.write_text("# No memory section\n")