---
id: PLN-0033
ticket: studio-editor-inline-type-hints-for-let-bindings
title: Inline hint specification and contract propagation
status: done
created: 2026-04-03
completed: 2026-04-03
tags: [studio, editor, specs, inline-hints, lsp, frontend-contract]
---

## Objective

Propagate DEC-0015 into the normative specification surfaces that define editor responsibilities, LSP semantic-read transport, and compiler/frontend contract authority for inline hints.

## Background

DEC-0015 locks inline hints as a host-generic editor capability with frontend-defined payloads, LSP-enforced transport, Studio rendering, decorative-only interaction, and partial-degradation preservation. No implementation plan may weaken those rules by inference.

The repository already has normative surfaces for editor behavior, semantic-read transport, and frontend-owned semantic contracts. Those surfaces must be updated before implementation splits across LSP, PBS, and Studio code.

## Scope

### Included
- Propagate DEC-0015 to Studio editor specs.
- Propagate DEC-0015 to integrated semantic-read specs.
- Extend compiler/frontend contract language where needed so frontend-owned hint metadata has a stable authority surface.
- Define the normative distinction between transitional approximation and final inline rendering.

### Excluded
- LSP DTO implementation.
- PBS hint payload production.
- Studio rendering code.

## Execution Steps

### Step 1 - Update the Code Editor workspace specification for inline hint rendering

**What:** Add normative editor requirements for decorative inline hints, host responsibilities, and inline-real final rendering.

**How:** Update the Studio Code Editor specification to state that:
- inline hints are host-generic editor capabilities;
- hint content remains frontend-owned;
- the editor renders but does not invent hints;
- hints are decorative only and do not alter text, selection, caret movement, or persistence;
- a transitional approximate stage may exist only as an explicit rollout step;
- the final completed capability is real inline rendering.

**File(s):**
- `docs/specs/studio/5. Code Editor Workspace Specification.md`

### Step 2 - Update the semantic-read phase specification for inline hint transport

**What:** Define inline hint transport as part of the semantic-read contract.

**How:** Update the semantic-read specification so it normatively states:
- inline/inlay hints are frontend-owned semantic payloads transported through `prometeu-lsp`;
- LSP owns the DTO and transport contract but not hint semantics;
- valid hint spans must survive partial degradation;
- the transport must preserve deterministic anchor information needed by Studio rendering.

**File(s):**
- `docs/specs/studio/7. Integrated LSP Semantic Read Phase Specification.md`

### Step 3 - Update compiler/frontend contract authority for frontend-owned hint metadata

**What:** Extend the compiler/frontend contract language so frontend-owned editor hint metadata has an explicit authority surface parallel to semantic presentation.

**How:** Update the compiler entrypoint/frontend contract specification to state that `FrontendSpec` or an equivalent accepted frontend-owned semantic contract surface remains the canonical source for static hint contract metadata when such metadata is required by downstream consumers.

The text must not imply Studio-owned or LSP-owned semantic hint policy.

**File(s):**
- `docs/specs/compiler/23. Compiler Pipeline Entry Points Specification.md`

## Test Requirements

### Unit Tests
- Not applicable for this spec-only plan.

### Integration Tests
- Not applicable for this spec-only plan.

### Manual Verification
- Review the updated specs against DEC-0015 and confirm all normative points are represented.
- Confirm the final-state requirement still says inline real rendering.
- Confirm the specs do not give Studio authority over hint existence or content.

## Acceptance Criteria

- [x] Studio editor specs define inline hints as decorative, host-generic, and final-state inline real.
- [x] Semantic-read specs define frontend-owned hint transport and partial-degradation preservation.
- [x] Compiler/frontend contract language preserves frontend ownership of hint semantics.
- [x] The specification set is sufficient for code plans without reopening DEC-0015.

## Dependencies

- Accepted decision `DEC-0015-studio-editor-inline-type-hints-contract-and-rendering-model.md`
- Existing Studio and compiler specifications.

## Risks

- Under-specifying the contract may force DTO churn later.
- Overloading existing semantic presentation wording may blur the distinction between static presentation metadata and dynamic hint payload transport.