Skills block not updated when reusing existing block

[cpfiffer]

Problem

When creating a new agent with --new, the skills block content is not updated if a skills block already exists for the project. This means changes to .skills/ directory are ignored unless you use --fresh-blocks.

Current Behavior

# Initial setup
mkdir .skills/my-skill
echo "skill content" > .skills/my-skill/SKILL.MD
letta --new  # Creates agent with skills block containing "skill content"

# Later: update skills
echo "updated skill content" > .skills/my-skill/SKILL.MD
letta --new  # ❌ Skills block still has OLD "skill content"

Root Cause

In src/agent/create.ts:

1. Lines 69-88: Discovers .skills/ and updates defaultMemoryBlocks with fresh content
2. Lines 122-131: Tries to reuse existing skills block by ID
3. Lines 140-143: If existing block found, reuses it (with OLD content)
4. Fresh content is only used when creating NEW block

// Lines 69-88: Fresh .skills/ content loaded
const skillsBlock = defaultMemoryBlocks.find((b) => b.label === "skills");
if (skillsBlock) {
  skillsBlock.value = formatSkillsForMemory(skills, resolvedSkillsDirectory);
}

// Lines 140-143: But if existing block found, reuses OLD content
if (existingBlock?.id) {
  blockIds.push(existingBlock.id);  // ⚠️ Ignores fresh skillsBlock.value above
}

Expected Behavior

Skills block should be updated on every agent creation to reflect current .skills/ directory:

// After loading existing blocks, update skills block with fresh content
const skillsBlockId = localSharedBlockIds.skills;
if (skillsBlockId && skillsBlock) {
  await client.blocks.update(skillsBlockId, {
    value: skillsBlock.value,  // Fresh .skills/ content
  });
}

Workaround

Use --fresh-blocks to force creation of new skills block with fresh content:

letta --fresh-blocks  # Nuclear option: all blocks fresh

Impact

• Users must use --fresh-blocks to pick up .skills/ changes
• --fresh-blocks also nukes global blocks (persona/human) which is too destructive
• Skills are advertised as "automatically discovered" but changes aren't reflected

Related

• This is separate from feat: Make --new safe by default, add --fresh-blocks for isolation #91 which fixes --new flag behavior
• Global blocks (persona/human) reusing old content is fine (rarely change)
• Skills block reusing old content is a bug (frequently changes)