can:// ids gain a <service> segment; collapse <app> (schema 2.1.0)

[rahlk]

Spec: codellm-devkit/.github → docs/design/specs/can-uri-service-segment.md
Coordination: codellm-devkit/.github#39

Problem

src/schema/v2/emit.ts:350 builds the application root with the language outermost:

const appId = `can://${LANGUAGE}/${appName}`;

so every durable id is can://typescript/<app>/<file>/<type>/<sig>, with no deployment
dimension. A polyglot microservice therefore has no single id root — its TypeScript and Python
halves land under unrelated authorities — and cocoa has had to build one outside the schema
(cocoa/system/facts.py:39 wraps our id as fn:<service>/can://…).

Per the spec, <service> becomes the outermost segment and <app> collapses into it:

before  can://typescript/<app>/<file>/<type>/<sig>
after   can://<service>/typescript/<file>/<type>/<sig>

Scope boundary

This repo only. Does not add cross-service edges (no RPC/HTTP call family — Epic E), does not
touch the keystone grammar docs, does not touch cocoa, and does not touch codeanalyzer-python
(its own issue). The can:// scheme name is settled and not in scope.

Does not attempt to reconcile the two known sibling divergences recorded in the
codeanalyzer-dotnet spec — UTF-16 vs UTF-8 span offsets, and unprefixed vs per-language Neo4j
labels. Both are real, both make this repo the outlier, and both are their own design session.

Goals

• src/schema/v2/emit.ts:350 — service becomes the outermost segment; <app> removed
• src/schema/v2/model.ts:39 — the id: string; // can://<lang>/<app> comment follows
• src/cli.ts:19 — --app-name <name> → --service <name>, same default (input dir name);
  src/options/options.ts:15 appName renamed with it
• src/build/neo4j/schema.ts — SCHEMA_VERSION → "2.1.0"; CanNode keys follow the ids
• homeExternals (emit.ts:301) — verify @external ids still compose from appId with no
  logic change: can://<service>/typescript/@external/<module>/<name>
• Anonymous-callback ordinal ids (<enclosing-can-id>@<line>:<col>) unchanged
• v2 tests + test/neo4j-schema.test.ts conformance updated

Caveats and known risks

• The version number understates the break. 2.1.0 is MINOR for a change that rewrites every
  durable id and the CanNode MERGE key — this repo's own rule in src/build/neo4j/schema.ts
  says MAJOR on a renamed key. Deliberate erratum, valid only because no consumer holds a
  can:// id today (typescript-sdk is pre-v2, zero references). Not precedent later.
• Persisted Neo4j graphs need a full re-ingest, not an incremental MERGE.
• Shared code is analyzed once per service by design: one run per service (spec D5).
• Renaming --app-name is a CLI break for existing callers. Whether to keep a deprecated
  alias is an open call the spec does not decide.
• Must land in lockstep with codeanalyzer-python's equivalent change; cocoa is gated on both.

Definition of done

• A no-flag run on a TS project emits can://<dir-name>/typescript/src/… — verified on a
  real run, not an asserted shape
• --service checkout emits can://checkout/typescript/src/cart.ts/CartService/checkout(userId)
• No emitted id contains an <app> segment distinct from the service
• External library targets resolve as can://<service>/typescript/@external/<module>/<name>
  and every callee backfilled at L2 points at a resolvable id
• Every edge endpoint resolves — call_graph, extends_ids/implements_ids,
  param_in/param_out — with zero dangling references
• Ordinal ids below the callable unchanged, including anonymous callbacks
• schema_version reads "2.1.0" in both the JSON envelope and the Neo4j contract
• test/neo4j-schema.test.ts passes — the emitter produces no undeclared label,
  relationship, or property