Corvus V4 Migration

What it does

When your agent uses it

• : migrating V4 consumer code to V5
• Understanding API differences between V4 and V5
• Using migration analyzers and code fixes
• : general V5 development (use other skills)

Example prompts

• “/corvus-v4-migration”

Workflow steps

4 steps, taken from the first numbered list in SKILL.md.

1. 1Install the migration analyzer package
2. 2Migrate file-by-file, building between each file
3. 3Follow the analyzer diagnostics (CVJ001-CVJ025) — each has a code fix
4. 4For AI-assisted migration, reference the transformation rules in

What it can do on your machine

Read from SKILL.md and the folder at commit 973097f. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are csharp and xml).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Corvus V4 Migration loads about 1.1k tokens when it runs. Until then it costs about 150 tokens; SKILL.md has 283 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~150

When it runs · the whole SKILL.md, loaded when a task matches

~1.1k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from corvus-dotnet/Corvus.JsonSchema at commit 973097f, republished under its Apache-2.0 licence (© corvus-dotnet). 283 words, ~1,147 tokens.

name

corvus-v4-migration

description

Migrate code from Corvus.Json V4 to Corvus.Text.Json V5. Covers namespace and type renames, parsing pattern changes, the mutation model shift from functional With*() to imperative Set*() with workspace/builder, validation API changes, composition type changes, migration analyzer diagnostics (CVJ001-CVJ025), and the Copilot-assisted migration workflow. USE FOR: migrating V4 consumer code to V5, understanding API differences between V4 and V5, using migration analyzers and code fixes. DO NOT USE FOR: general V5 development (use other skills), modifying the V4 engine itself.

// V4
using ParsedValue<MyType> parsed = ParsedValue<MyType>.Parse(json);
MyType value = parsed.Instance;

// V5
using ParsedJsonDocument<MyType> doc = ParsedJsonDocument<MyType>.Parse(json);
MyType value = doc.RootElement;

// V4
JsonString name = person.Name;
string nameStr = (string)name;

// V5
JsonElement name = person.Name;
string nameStr = (string)name;
// Or: person.Name.GetString() for the string value

// V4 (functional — returns new instance)
person = person.WithName("Alice");

// V5 (imperative — mutates in place)
using JsonWorkspace workspace = JsonWorkspace.Create();
using var builder = person.CreateBuilder(workspace);
builder.RootElement.Name = "Alice";

// V4
ValidationContext result = value.Validate(ValidationContext.ValidContext, ValidationLevel.Detailed);
bool isValid = result.IsValid;

// V5 — EvaluateSchema() returns bool directly
bool isValid = value.EvaluateSchema();

// V5 — with detailed results, pass a collector
var collector = new MyResultsCollector();
bool isValid = value.EvaluateSchema(collector);

© corvus-dotnet, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in .github/skills/corvus-v4-migration of corvus-dotnet/Corvus.JsonSchema.

Open the folder on GitHubat commit 973097f