Permission denied on write
AI tries to write
Chapter 3/scene-1.scene→ 400 INVALID_PATH. This article: diagnosis + fixes.

Read the error
The 400 INVALID_PATH message is explicit:
INVALID_PATH: Cannot write to /Chapter 3/scene-1.scene.
This is a structured file in a Script Studio book.
Writable paths: .script_studio/planning/**/*
Read-only paths: *.scene, *.character, *.storyline, *.note, *.location, season.json, episode.json, series.json
Why this path is read-only
Script Studio structured files are read-only over MCP — see Structured protections.
Two fixes
Path 1: write to planning, apply in Slima UI
Don't write .scene files — write proposals into .script_studio/planning/:
.script_studio/planning/scene-3-1-revision.md
Then in Slima Script Studio UI, open the scene and manually apply the AI's proposal.
Path 2: use the in-Slima AI Coach
The AI Coach inside the Slima editor (not MCP) can write structured files — because it goes through the app internally, not MCP.
Prevent: read the schema resource first
AI can read in advance:
slima://books/{book_token}/schema
Gets exact writable / readonly paths and avoids the dead-ends.
See: Schema resource
Hit it in a Writing Studio book?
Rare, but possible causes:
1 · Book in Trash
Soft-deleted books aren't writable. Fix: Restore from trash
2 · Shared to you read-only
(Sharing isn't in v1 — future feature)
Related
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