feat(cli): enable shared agent board via experimental env flag

[marius-kilocode]

What Problem This Solves

Kilo Swarm (the experimental shared agent board) could only be turned on through the experimental.shared_agent_board config key. Users who opt into experiments globally with KILO_EXPERIMENTAL=true, or who want to toggle the board through one environment variable, had no way to enable it without editing config.

Why This Change Was Made

• Add experimentalSharedAgentBoard to the central runtime flags with enabledByExperimental("KILO_EXPERIMENTAL_SHARED_AGENT_BOARD"), so the specific variable and the KILO_EXPERIMENTAL umbrella both work.
• Add a BoardEnabled.resolve helper under packages/opencode/src/kilocode/board/ and route every existing gate (board tools, board notifier, agent permissions, tool registry, session tool notify wiring) through it, instead of scattering new || flag checks.
• Resolution rule: the board is enabled when config is true or the flag is true. An explicit config false does not disable the board when the flag is set, because the environment variable is an additional enable path. The config key remains the source of truth for an explicit true.
• Shared upstream files only change where the RuntimeFlags service must be threaded through, and those lines sit inside existing kilocode_change regions.

User Impact

Setting KILO_EXPERIMENTAL_SHARED_AGENT_BOARD=true, or the umbrella KILO_EXPERIMENTAL=true, enables board_read and board_post without changing config. Existing config based enablement and the default disabled state are unchanged. Tool names, stored IDs, migrations, history, and permissions are untouched.

Evidence

• bun run typecheck from packages/opencode/: exit 0.
• bun test ./test/kilocode/board-enabled.test.ts ./test/kilocode/board-tools.test.ts ./test/kilocode/board-context.test.ts: 26 pass, 0 fail.
• bun test ./test/kilocode/tool-registry-indexing.test.ts ./test/kilocode/chart-tool-gating.test.ts ./test/kilocode/notebook-tools.test.ts ./test/kilocode/tool/memory-save.test.ts ./test/kilocode/tool/send-file.test.ts ./test/kilocode/system-prompt.test.ts: 71 pass, 0 fail.
• bun test ./test/kilocode/board-live.test.ts ./test/kilocode/server/board.test.ts ./test/kilocode/board/store.test.ts: 34 pass, 0 fail.
• bun test ./test/effect/runtime-flags.test.ts ./test/tool/registry.test.ts: 58 pass, 0 fail.
• bun run script/check-opencode-annotations.ts --worktree: all shared upstream changes are annotated with kilocode_change markers.

Adds a patch changeset.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (20 files)

• .changeset/board-env-flag.md
• packages/opencode/src/agent/agent.ts
• packages/opencode/src/effect/runtime-flags.ts
• packages/opencode/src/kilocode/agent/index.ts
• packages/opencode/src/kilocode/board/context.ts
• packages/opencode/src/kilocode/board/enabled.ts
• packages/opencode/src/kilocode/tool/board.ts
• packages/opencode/src/kilocode/tool/registry.ts
• packages/opencode/src/session/prompt.ts
• packages/opencode/src/session/tools.ts
• packages/opencode/src/tool/registry.ts
• packages/opencode/test/kilocode/board-context.test.ts
• packages/opencode/test/kilocode/board-enabled.test.ts
• packages/opencode/test/kilocode/board-tools.test.ts
• packages/opencode/test/kilocode/chart-tool-gating.test.ts
• packages/opencode/test/kilocode/notebook-tools.test.ts
• packages/opencode/test/kilocode/system-prompt.test.ts
• packages/opencode/test/kilocode/tool-registry-indexing.test.ts
• packages/opencode/test/kilocode/tool/memory-save.test.ts
• packages/opencode/test/kilocode/tool/send-file.test.ts

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_{Review guidance: REVIEW.md from base branch main}