Prompt Disclosure Layers

Every prompt file costs tokens on every injection. OCP therefore sorts its rules into disclosure layers by violation cost, not file size — a rule is paid for exactly when the agent that needs it runs, and never by the agents that don't.

The layers

Layer	Carrier	Paid when	Contents
L0	opencode.jsonc:instructions	every step of every agent	iron rules: rfc-keywords, output-protocol, verification-honesty, routing-index
L1	agent prompt field, assembled from {file:} markers	while that agent runs	role rules: coding pack, sql-migration, review criteria
L2	skills/*/SKILL.md metadata	resident every step, visibility gated by permission; body loads on demand via the slash-command launchers in commands/*.md	scenario rules: workflow protocols (sdd-workflow, dev, goal, handoff, …)
L3	your project's AGENTS.md (OpenCode native)	when files in that directory are read	your personal / project rules

L0 is the expensive layer (paid × steps × agents), so it stays under a hard token budget enforced by scripts/measure-prompts.ts in the release gate.

Single source of truth. Agent definitions (mode, model, permission, tools, prompt assembly) live only in the jsonc agent block. The prompts/*.md fragments are pure bodies without frontmatter, and must never live under agents/ in the installed config: opencode auto-discovers agents/*.md as agent definitions whose frontmatter/body silently override the jsonc block (verified v1.18.25). prompts/ is not auto-discovered.

The L1 routing matrix

Agents	Attached rule files
code, fast-coder, java-dev, python-dev, go-dev, rust-dev, node-dev, frontend-dev, devops, qa	coding pack: coding-principles + comment-strategy + edit-protocol + test-scope
dba	coding pack + sql-migration
code-review	coding-principles + comment-strategy + test-scope (no edit-protocol — editing is denied)
code-review-fast	shared review body + coding-principles (P0/P1 triage; no nit/full test-scope review)
codegraph-scout, gitnexus-scout	compact graph-evidence bodies only; no L1 instructions or native tools
architect, advisor, security	coding-principles only (review criteria)
build, plan, explore, researcher, tech-writer, vision	none — L0 only

Per-step visibility gating

Two resident layers are gated by per-agent permissions instead of disclosure (opencode v1.18.25 semantics):

• Skills block — { "skill": { "name": "deny" } } drops a skill from the resident skills block; { "*": "deny" } empties the block. Workflow skills stay visible only for the build, plan, code primaries; every subagent denies "*".
• MCP tool surface — "<server>_*": { "*": "deny" } hides both the tools and the mcp_instructions block. The code-intel servers (serena, codegraph) stay only with agents that actually query code.
• L0 stripping — the lite primary opts out of L0 entirely: its inline prompt carries the <!-- lite-mode --> sentinel and plugins/lite-mode.ts strips it plus every Instructions from: block from the system prompt.

In tiered review, each graph backend is exposed only to its selected Scout; bounded relationship evidence crosses to the deep reviewer instead of graph tool definitions. Scout selection is optional: no ready backend means direct deep review.

Quantify any change with scripts/measure-prompts.ts before releasing.

Plugin injection gating

Runtime protocol injections (guardrail notices, scoped protocols) are policy-gated by plugin-scope.json (repo root, shipped), consumed solely by plugins/shared/plugin-scope.ts. Every injector awaits scoped(input, output.system, "<plugin-id>", client) before touching the system prompt.

• Identification — text identifiers (the lite sentinel, the title-generator prefix) plus session ground truth: a non-empty parentID marks a subagent step (cached per session; consulted only when text detection misses).
• Policy — per-plugin deny/allow lists using the scope grammar x (identity or state) and x:* (any identity in state x); unspecified plugins inherit the "*" entry. Shipped default: deny lite, utility, subagent:* — injections stay out of stripped primaries and every subagent step. One shipped override: project-profiler denies only lite/utility — backend routing is a subagent's work discipline (explore.md defers backend choice to the session profile). Workflow protocols need no gate at all: they live at L2 and load only when their slash command runs.
• Fail-open — any policy error skips the injection rather than breaking the step.

Guard rails

• routing-index.md (L0) keeps pointers to every on-demand rule, so demoting a rule never loses the iron obligation behind it (e.g. SQL migrations must still route to @dba; SDD flows must still load the skill first).
• L1 files may cross-reference each other with shorthand (cp#N) only within the same disclosure unit — every agent that cites cp#N carries coding-principles.md.
• Upgrades always propagate: the installer takes the template's instructions array and factory agents as authoritative; only agents you added yourself are preserved verbatim.

Personal rules

Personal or project-specific rules belong in L3: an AGENTS.md at your project root (OpenCode loads it natively when the project is active). Do not edit the shipped instructions array — the installer overwrites it with the template on every upgrade by design.