Add OMP (Oh-My-Pi) as a first-class importable provider

[jms830]

Closes #1176.

What

Adds OMP — Oh-My-Pi, a downstream fork of Pi — as a first-class provider alongside claude, codex, opencode, and pi. OMP ships its own binary (omp), home directory (~/.omp), and plugin ecosystem, but preserves Pi's --mode rpc wire protocol and JSONL session schema verbatim.

After this PR, OMP users can:

• See OMP in paseo provider ls, the in-app provider catalog, and the agent picker
• Import OMP sessions started in the terminal: paseo import <session-id> --provider omp --cwd <cwd>
• Define custom providers that extends: "omp" in ~/.paseo/config.json

Why

OMP is a real-world Pi fork with its own omp CLI and ~/.omp/agent/sessions/<sanitized-cwd>/<ts>_<uuid>.jsonl storage layout. Today OMP users have two unappealing options:

1. Run Paseo against vanilla Pi. Loses access to OMP plugins, OMP-installed extensions, and OMP's session history.
2. Hack the Pi provider via env + custom-provider extends. Set PI_CODING_AGENT_DIR=~/.omp/agent, define a custom provider with extends: "pi" and command: ["omp", "--mode", "rpc"]. The UI still calls it "Pi", session metadata gets stamped provider: "pi", and any future Pi/OMP divergence breaks silently.

OMP and Pi are binary-compatible (same JSONL header {type:"session",version:3,id,cwd,...}, same RPC shape, same pi-mcp-adapter extension), so first-class support is a near-zero-cost integration that mirrors the existing Pi adapter pattern.

How

The Pi adapter is parameterized over a new PiFamilyConfig:

// packages/server/src/server/agent/providers/pi/family-config.ts
export interface PiFamilyConfig {
  readonly providerId: string;          // "pi" / "omp"
  readonly binaryName: string;          // "pi" / "omp"
  readonly binaryEnvVars: readonly string[];
  readonly homeDirName: string;         // ".pi" / ".omp"
  readonly agentDirEnv: string;
  readonly sessionDirEnv: string;
  readonly displayLabel: string;
  readonly mcpAdapterMarker: string;    // "pi-mcp-adapter" — OMP reuses Pi's adapter
}

export const PI_FAMILY: PiFamilyConfig = { ... };
export const OMP_FAMILY: PiFamilyConfig = { ... };

PiRpcAgentClient / PiRpcAgentSession / PiCliRuntime accept the family via constructor and thread family.providerId through all AgentStreamEvent emissions, AgentPersistenceHandle metadata, diagnostic output, and MCP adapter detection. Pi-side defaults (PI_FAMILY) are unchanged — all existing Pi tests pass byte-for-byte.

OmpRpcAgentClient in providers/omp/agent.ts is a thin subclass of PiRpcAgentClient that injects OMP_FAMILY and overrides listPersistedAgents to use OMP-specific offline JSONL discovery (see next section).

Registered in:

• packages/server/src/server/agent/provider-manifest.ts — AGENT_PROVIDER_DEFINITIONS
• packages/server/src/server/agent/provider-registry.ts — PROVIDER_CLIENT_FACTORIES
• packages/server/src/shared/importable-providers.ts — IMPORTABLE_PROVIDERS
• packages/server/src/server/persisted-config.ts — BUILTIN_PROVIDER_IDS
• packages/server/src/server/daemon-e2e/agent-configs.ts — allProviders
• packages/cli/src/commands/agent/import.ts — IMPORT_PROVIDER_LIST

Session discovery: deliberately split from Pi

#1154 ("Rewind chat or files from any user message") removed providers/pi/session-descriptor.ts and replaced Pi's listPersistedAgents with return [], because Pi now uses the runtime paseo_capture_entries extension to track session identity for sessions started inside Paseo.

That works for Pi-launched-from-Paseo, but it doesn't help users who run omp (or pi) directly in their terminal and later want to import that session into Paseo.

For OMP this PR adds a new providers/omp/session-descriptor.ts that does offline JSONL discovery of ~/.omp/agent/sessions/**/*.jsonl. It mirrors the historical Pi descriptor pattern (resolution order: OMP_CODING_AGENT_SESSION_DIR → OMP_CODING_AGENT_DIR/settings.json:sessionDir → <cwd>/.omp/settings.json:sessionDir → ~/.omp/agent/sessions/) but parameterized over PiFamilyConfig so future Pi-family forks can reuse it.

Pi continues to use the runtime extension path as its canonical import strategy. The OMP descriptor is scoped to OMP paths and does not alter Pi behavior.

If reviewers want Pi import restored on the same offline-JSONL path (e.g. by passing PI_FAMILY to listOmpPersistedAgents and renaming the module to providers/pi-family/session-descriptor.ts), it's a one-line wiring change from this shape. I left Pi untouched on this PR to keep the review surface minimal and not contradict #1154's direction.

Testing

Layer	Result
Pi regression	34/34 pre-existing Pi tests pass unchanged
OMP unit	11 new tests: 7 in omp/session-descriptor.test.ts (default path, env override, settings override, project .omp/settings.json, symlinks, sort+filter, family isolation), 4 in omp/agent.test.ts (provider id, session provider id, end-to-end listPersistedAgents, isolation from PI_CODING_AGENT_DIR)
Full server test suite	1649 passed / 40 skipped (153 test files), zero new failures
Format / lint / typecheck	npm run format:check, npm run lint, npm run typecheck clean across all 8 workspaces
Live smoke (against a real OMP install)	OmpRpcAgentClient.listPersistedAgents() against this dev's real ~/.omp/agent/sessions/ returned 5 well-formed PersistedAgentDescriptor objects with provider:"omp", correct cwds, titles, and JSONL nativeHandles. paseo provider ls --json shows OMP as a first-class entry. paseo agent import <id> --provider omp --cwd <cwd> reaches OmpRpcAgentClient.resumeSession and spawns the real omp --mode rpc process.

What this does NOT change

• Pi adapter behavior. Pi tests, Pi env vars, Pi defaults — all unchanged.
• Pi's listPersistedAgents. Still return [] (the post-Rewind chat or files from any user message #1154 state).
• The runtime resume contract.

Files

• New: packages/server/src/server/agent/providers/pi/family-config.ts
• New: packages/server/src/server/agent/providers/omp/agent.ts
• New: packages/server/src/server/agent/providers/omp/session-descriptor.ts
• New: packages/server/src/server/agent/providers/omp/session-descriptor.test.ts
• New: packages/server/src/server/agent/providers/omp/agent.test.ts
• Modified: packages/server/src/server/agent/providers/pi/agent.ts (parameterize over family, PI_PROVIDER → this.providerId, helpers take family arg, runtimeSettings becomes protected)
• Modified: packages/server/src/server/agent/providers/pi/cli-runtime.ts (accept family, default to PI_FAMILY)
• Modified: packages/server/src/server/agent/provider-manifest.ts, provider-registry.ts, shared/importable-providers.ts, persisted-config.ts, daemon-e2e/agent-configs.ts, CLI agent/import.ts
• Modified: docs/providers.md, public-docs/supported-providers.md, CHANGELOG.md

16 files, +1140 / -67 lines.

Follow-ups (out of scope here)

• Lift omp/session-descriptor.ts to providers/pi-family/session-descriptor.ts if you want Pi imports restored on the same offline path.
• Add an omp icon to the in-app provider catalog (matches Pi for now via the generic terminal icon).
• Add a one-click install path for OMP in the in-app provider catalog (the same surface Pi has).
• Factor history-mapper.ts, tool-call-mapper.ts, rpc-types.ts into providers/pi-family/ if OMP plugins ever start emitting JSONL frames Pi can't parse.