frame-spine-lookup

name	frame-spine-lookup
description	Frame spine lookup methodology for mid-turn slice retrieval by spine-aware specialists. Use when a dispatched specialist needs to fetch an addressable plan slice from the durable plan-issue comment. DO NOT USE FOR: authoring plan spines, emitting frame credits, frame-port adapter declarations, or custom transport implementation.

Frame Spine Lookup

Methodology for retrieving addressable frame-spine slices during a specialist turn without loading the full implementation plan.

When to Use

• When Code-Conductor dispatches a specialist with a frame spine, an active slice, and the durable plan comment id.
• When a specialist needs a depth-1 dependency slice or another explicitly addressable slice during the same turn.
• When the specialist must verify that the dispatched spine is still current before relying on a slice fetched from GitHub.

Purpose

Keep specialist prompts focused while preserving plan traceability. The durable plan-issue comment remains the source of truth; this skill defines how a specialist fetches that comment, asks the production parser helpers for the needed step, and handles stale-spine detection.

Dispatch Inputs

Code-Conductor must provide the specialist with:

• Repository owner and name.
• The GitHub issue comment id for the <!-- plan-issue-{ID} --> comment.
• The GitHub issue comment id for the <!-- frame-slices-{ID} --> sibling comment, required when the dispatched spine's slice_comment_id field is present. Code-Conductor already has the <!-- frame-spine ... --> block in its own dispatch context (see agents/Code-Conductor.agent.md) and reads slice_comment_id from it directly to populate this input — the specialist never reads slice_comment_id itself. Absent when the spine has no slice_comment_id (legacy/unsplit plan); see Operational Contract step 1 for the resulting single-fetch behavior.
• The target spine step id, such as s4.
• The spine generated_at value captured at dispatch time.

The specialist must carry the dispatched generated_at into lookup. The lookup uses generated_at to compare the dispatch-time spine against the current plan-issue comment body.

Operational Contract

1. Fetch the durable plan payload with the GitHub issue comments API. See platforms/claude.md and platforms/copilot.md for tool-specific invocations.

   Read the response body field as the plan-issue comment body. Do not parse issue timelines or search results when the comment id is already known.

   When a sibling comment id was dispatched (the spine's slice_comment_id was present at dispatch time), also fetch the <!-- frame-slices-{ID} --> sibling comment body, keyed on the dispatched sibling id, with the same GitHub issue comments API. Before concatenating, verify the fetched sibling body carries a <!-- frame-slices-{ID} --> marker whose {ID} matches the dispatched issue number. If the marker is absent or names a different issue, stop before invoking -Op Lookup and report sibling-identity-mismatch to Conductor rather than proceeding with a body that may belong to the wrong issue — a copy-pasted or stale sibling id is a zero-adversary path to executing a foreign requirement contract. This check runs at the shim, before frame-spine-core.ps1 is invoked: the core script has no issue-number parameter to perform it, and adding one would widen the signature the shim concatenation approach was chosen to avoid.

   When the identity check passes, concatenate the plan-issue comment body and the sibling body with a single blank line (\n\n) between them — plan body first, sibling body second — and pass the concatenated text to -Op Lookup as a single comment body. When no sibling id was dispatched (legacy plan, no slice_comment_id on the spine), fetch only the plan comment and pass it unchanged; this is the current single-fetch behavior and its shape does not change.

2. Invoke the production frame-spine parser helpers through the lookup operation. The command shape must match this contract:

   pwsh -File .github/scripts/lib/frame-spine-core.ps1 -Op Lookup -CommentBodyPath {path} -GeneratedAt {generated_at} -StepId {id} -Format Json
   

   The implementation may pass the fetched body by a supported path or stream (-CommentBodyPath for file-based, -CommentBodyStdin for piped stdin), but the operation remains -Op Lookup against frame-spine-core.ps1, with the dispatched generated_at value and requested -StepId {id} present in the lookup invocation. When a sibling was fetched, the body passed here is the step-1 concatenation of the plan comment and the sibling comment — the command shape and / invocation are unchanged either way; only the content behind / differs. Always pass so the response is machine- parseable JSON regardless of platform; parse the returned field to determine the lookup outcome (do not rely on exit code alone — see Exit Codes below).

Exit Codes and Status Values

Always parse the JSON status field to determine the lookup outcome. Do not branch on exit code alone — stale-spine exits 0, not 1.

Status	Exit code	Meaning
ok	0	Slice retrieved successfully; slice field contains content.
stale-spine	0	Dispatched spine is no longer current, or the fetched sibling's frame-slices-generated-at stamp diverges from the spine's generated_at; return to Conductor.
missing-spine	1	Comment body contains no <!-- frame-spine --> block.
invalid-spine	1	Spine block is present but malformed (parse error).
sibling-unstamped	1	Spine carries slice_comment_id but the concatenated body has no frame-slices-generated-at marker — a writer defect, not legacy history (863-D3/AC5).
missing-slice	1	Spine is valid but the requested step id was not found.
duplicate-slice-id	1	The concatenated corpus carries two or more <!-- frame-slice --> blocks for the requested step id.
error	1	Unexpected error; message field contains the reason.

Wrapper-level error codes (when the outer process fails before the script can run) are surfaced by the platform shim — see platforms/copilot.md and platforms/claude.md for gh-not-installed, gh-auth-expired, pwsh-not-found, and sibling-identity-mismatch error handling. The last is a shim-level check (see Operational Contract step 1) — it never reaches frame-spine-core.ps1, so it is not one of the core status values above.

Stale-Spine Handling

generated_at can change when the plan is amended or re-emitted. Lookup must not treat timestamp-only churn as a semantic change until the F2.2 hash-elision filter has ignored transport-only generated_at differences. If the filtered comparison still shows that the dispatched spine is no longer the current plan spine, lookup returns stale-spine.

Specialist response on stale-spine is intentionally narrow:

• Do not continue implementation, tests, refactoring, or documentation from the stale slice.
• Report that the lookup returned stale-spine.
• Return control to Conductor so Conductor can re-dispatch the specialist with current spine context.

Tool-Grant Verification

The specialist shells that can perform lookup already have the required tool grants.

Claude Code specialists (Read and Bash):

• agents/code-smith.md
• agents/test-writer.md
• agents/doc-keeper.md
• agents/refactor-specialist.md

Copilot specialists (execute/runInTerminal or execute wildcard):

• agents/Code-Smith.agent.md
• agents/Test-Writer.agent.md
• agents/Doc-Keeper.agent.md
• agents/Refactor-Specialist.agent.md
• agents/Specification.agent.md
• agents/UI-Iterator.agent.md
• agents/Experience-Owner.agent.md

agents/Research-Agent.agent.md is excluded: it has only read, edit, search, and web grants — no execute/*. Copilot spine lookup for Research-Agent is deferred to #544.

Do not edit specialist shells for this contract unless a future test proves the grants drifted.

Non-Goals and Deferred Work

• Copilot parity shims for spine lookup shipped in #514. Research-Agent Copilot spine lookup is deferred to #544.
• A custom MCP server lookup path is deferred and is a non-goal for this skill.
• This skill is supporting methodology only. It declares no provides: field and does not fill a frame port.
• Goal-contract plans (issue #872) are out of scope for this skill's slice dispatch. A plan-variant: goal-contract plan (see skills/plan-authoring/SKILL.md § Goal-contract plan variant) carries no <!-- frame-spine ... --> block and no <!-- frame-slices-{ID} --> sibling comment — the <!-- goal-contract --> block replaces both (872-D8). Such plans are never slice-dispatched through this skill's Operational Contract. Invoke-FSCSpineLookupCli returning missing-spine (§ Exit Codes and Status Values above) for a goal-contract-only plan body is the intended fail-loud backstop, not a bug (872-D7 item 2): no code change closes this path, because a goal-contract plan is meant to be executed by the future goal-run harness (#874), not walked by Spine-Runner or looked up mid-turn by a specialist.
• The credit-ledger degradation note below covers the brief too. Get-FCLLatestParsedFrameSpine returning $null for a brief is the same expected behavior it is for a goal-contract plan, and for the same reason: no spine exists to parse, so zero spine-sourced credit rows is the correct answer rather than a defect. Recorded here because #942 deletes the only shape that note currently names.
• Brief plans (issue #941) are out of scope for the same reason. A plan-variant: brief plan (see skills/plan-authoring/SKILL.md § Brief plan variant) carries no <!-- frame-spine ... --> block and no <!-- frame-slices-{ID} --> sibling, because it has no numbered implementation steps to route. missing-spine is the intended fail-loud backstop here too; a brief is read whole by its executor rather than slice-dispatched.
• Spine-reader enumeration (872-D7 / AC2). The production readers of the frame-spine mechanism, in full, are: frame-validate-core.ps1 (the structural-coverage validator, .github/scripts/lib/frame-validate-core.ps1), orchestra-spine.ps1 (.github/scripts/orchestra-spine.ps1, the human-readable spine renderer), (, the terminal-credit harvester), and — the lookup shim implemented in that this skill's Operational Contract dispatches to. This is the shipped home for that enumeration; AC2's "spine-reader enumeration documented" requirement is satisfied here rather than living only inside the #872 plan comment.

Platform-specific invocation

See platforms/claude.md for Claude Code tool bindings (Bash and Read) and platforms/copilot.md for Copilot VS Code tool bindings (execute/runInTerminal). Platform shims are the only location where tool names appear; the Operational Contract above is tool-agnostic.

Gotchas

Trigger	Gotcha	Fix
Specialist sees a stale slice	Continuing from old context can apply the wrong requirement contract	Return control to Conductor for re-dispatch
Comment id is available	Searching issue comments can select an older plan marker	Fetch gh api repos/{owner}/{repo}/issues/comments/{id} directly