fix(mobile): stabilize Local Studio agent scan

[0xSero]

Summary

• stabilize Local Studio agent discovery across the controller's cold-registration window
• keep generic KittyLitter scans immediate
• reuse one shared Rust inventory path for scanner and connection, removing the duplicate connection retry loop
• project the mode choice through thin iOS and Android calls

Root cause

The Local Studio controller can answer an inventory request before Pi, Codex, and other enabled agent bridges have registered. Litter scanned once and disabled Connect when that first inventory was empty, while the later connection path contained retries the user could never reach.

Verification

• focused Rust recovery and Local Studio connection-expansion tests passed
• full codex-mobile-client library suite: 774 passed, 0 failed, 5 ignored live-only tests
• generated Swift and Kotlin bindings successfully
• Android unit tests, debug AndroidTest compilation, and debug APK assembly passed
• iOS fast simulator build passed
• live iPhone 17 Pro simulator flow passed against the Pop!_OS controller: paste Local Studio connection JSON, discover Pi and Codex, select agents, connect, and observe the pairing sheet close
• live controller inventory found Codex, Pi, OpenCode, Claude, Droid, Hermes, and Shell; multiplexed connection attached every available agent
• Pop!_OS mobile website exercised progressive streaming, rendered reasoning, and completed a shell tool call
• installed Local Studio desktop app completed a fresh shell tool call and rendered the completion; an existing task confirmed desktop reasoning rendering
• the identical pre-rebase patch passed GitHub Mobile CI shared-prep, android, and ios; final head 517f2d69 passed release planning and the Windows npm test, while its Mobile CI rerun is queued for shared runner capacity

Review notes

• Local Studio waits through the same bounded 500/1000/1500 ms registration window previously hidden in the connection path
• refreshes merge by agent name, update later metadata, and retain earlier inventory if a later refresh fails
• KittyLitter behavior remains immediate
• no generated bindings or temporary live-test credentials are committed
• physical-device and Android-emulator runtime validation were not performed in this pass

[0xSero]

Self-review on 517f2d69 (after rebasing onto current origin/main):

• No correctness, parity, or cleanup findings remain.
• The patch is limited to six files (58 insertions / 34 deletions); 30 of the added lines are test coverage.
• The connection path's duplicate registration retry loop was removed. Scanner and connection now use the same shared Rust inventory stabilization path.
• Local Studio alone opts into the bounded registration wait; generic KittyLitter scans remain immediate.
• Inventory merges by stable agent name, replaces stale metadata, avoids duplicates, and retains the best known inventory if a later refresh errors.
• Swift and Kotlin only select the mode; registration policy remains shared in Rust.
• The rebased commit has the same stable patch ID as the fully validated pre-rebase commit.

Validation and the remaining physical-device / Android-runtime limits are recorded in the PR body. Updated CI is running on the rebased head.

[0xSero]

Cleanup audit: the shared-Rust refactor is aligned with the architecture (one inventory retry/merge path, thin platform mode selection), the diff is conflict-free, and Mobile CI is fully green. Keep this draft until the actual changed surface is proven: Local Studio pairing scan on an installed iOS build and Android build must recover from an initially empty inventory, show all later-registered agents without restarting, and keep generic KittyLitter scans immediate. The existing controller/browser/desktop proofs validate the host, not those two mobile scanner surfaces.

[0xSero]

Closing as superseded by release PR #219. I compared commit 9b44327d in #219 with this PR: the six-file Local Studio scan patch is content-identical, while #219 is based on the latest main and carries the same fix into the 1.7.0 release matrix. The detailed live-controller/iOS/desktop evidence from this PR remains the acceptance record; #219 still needs its documented Android and release gates.