feat(wallet): add BRC-98 ECPM semantic module

[connormurray2]

Revision

This PR now implements BRC-229 as the ecpm BRC-98 semantic module, replacing the earlier optional WalletInterface.multiplyPoint approach.

The existing branch and review history are preserved. Commit a1eaaa6c0 reverses the public SDK method, SDK test, and associated bundle-budget increases from the first three commits, then adds the module-based implementation.

The companion full-text BRC rewrite is posted as a review suggestion on BRCs #230.

Protocol

Applications continue to call the fixed BRC-100 getPublicKey method:

p ecpm <apply|remove> <pointHex> <logicalProtocolID>

keyID, counterparty, privileged, privilegedReason, and seekPermission remain in their existing GetPublicKeyArgs fields.

The module derives one scalar under the canonical namespace:

[securityLevel, "p ecpm <logicalProtocolID>"] + keyID + counterparty

The operation and point are deliberately excluded from the derivation identity:

• apply returns d·P;
• remove returns d⁻¹·P;
• both therefore select the same scalar and round-trip exactly.

The logical protocol ID is capped at 273 characters so the canonical p ecpm derivation namespace remains within BRC-43's 280-character limit.

Wallet Toolbox semantic module hook

PermissionsModule gains an optional, backwards-compatible handler:

handleRequest?: (
  request: PermissionsModuleRequest,
  next: PermissionsModuleNext
) => Promise<unknown>

A semantic module can return the conforming BRC-100 result directly or invoke the underlying operation once through guarded next. Existing onRequest/onResponse modules remain unchanged.

ECPM returns { publicKey } directly and does not call ordinary getPublicKey, because ordinary BRC-43 derivation returns a child public key over the fixed generator (or the named counterparty's child key), not d·P.

Installable reference package

This adds @bsv/ecpm-permission-module@0.1.0 alongside BTMS and the existing wallet module packages.

Wallet hosts register it as:

const ecpm = createEcpmModule({
  keyDeriver: setup.keyDeriver,
  authorize: request => showTrustedWalletPrompt(request),
  privilegedKeyDeriver: reason => acquirePrivilegedKeyDeriver(reason)
})

const wallet = new WalletPermissionsManager(setup.wallet, adminOriginator, {
  permissionModules: { ecpm }
})

The privileged provider is optional and is acquired only after authorization. Ordinary and privileged permission grants are isolated. Level 2 grants are counterparty-scoped, seekPermission: false fails without a cached grant, and concurrent equivalent prompts are deduplicated.

Security boundary

• Only getPublicKey is accepted under p ecpm; signing, HMAC, and encryption cannot reuse the scalar.
• Identity-key and forSelf: true requests are rejected.
• Points and public-key counterparties must be canonical lowercase compressed secp256k1 points.
• The x-coordinate is range-checked before parsing, preventing reducing parsers from accepting a different point.
• The application receives only { publicKey }; key derivers, roots, and private scalars remain in trusted wallet/module code.
• Privileged derivation fails closed when the host does not provide it.

Verification

• full workspace build: pass
• full workspace typecheck: pass
• full workspace tests: pass
• repo lint and formatting: pass
• ECPM unit/property tests: 41 pass
• ECPM coverage: 98.52% statements / 97.32% branches / 98.42% lines
• ECPM mutation score: 86.44% (255 killed, 40 survived, 0 no-coverage)
• exact-tarball browser contract: pass
  • Vite: 104,734 raw / 36,028 gzip / 30,031 brotli
  • esbuild: 108,443 raw / 41,505 gzip / 35,604 brotli
• exact packed ESM consumer and declaration checks: pass
• cross-package version governance: pass

The repository health run exposed four expired documentation reviews with real
source drift. They were reverified against the current route registries,
Dockerfiles, environment examples, package manifests, and intervening commits;
the corrected service versions, health routes, deployment guidance, and cloud
environment names are included in 4632f51f9. Documentation policy and the
complete rendered docs/link build now pass.

The final repository-health evaluator is still blocked by three pre-existing
governance exceptions whose owner review dates expired on 2026-08-23/24:
scorecard-release-token-permission,
image-size-unpublished-advisory-patch, and
legacy-sonar-analysis-suppressions. Renewing or resolving security and
quality exceptions requires an explicit maintainer governance review; this PR
does not extend them merely to make CI green.

[ty-everett]

Revised this existing PR/branch in place; no replacement PR was opened.

• a1eaaa6c0 replaces the optional SDK multiplyPoint method with the
  installable BRC-98 p ecpm semantic module and the backwards-compatible
  Wallet Toolbox handleRequest hook.
• 4632f51f9 substantively re-verifies the four service/reference pages that
  expired during this run; docs policy, render, and link validation now pass.
• The complete BRC-229 replacement is posted as an apply-ready review
  suggestion: BRC-229: Wallet-Native Elliptic Curve Point Multiplication BRCs#230 (comment)

Local verification is recorded in the updated PR description, including the
full workspace suite, 98.52% ECPM statement coverage, 86.44% mutation score,
browser budgets, and exact packed consumers.

The remaining repository-health failure is base governance state, not a feature
failure: three security/quality exceptions reached their owner-review dates on
2026-08-23/24. I have not renewed those exceptions without the required
maintainer governance review.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud