perf(mcp): drop duplicated structured arrays from get_instructions (−51% payload)

[simple-agent-manager]

Summary

get_instructions — the tool every SAM agent session must call before doing anything — was sending every knowledge observation and every policy twice: once rendered as markdown in knowledgeDirectives/policyDirectives, and again as structured JSON in knowledgeContext/policyContext, labelled "Also include structured data for programmatic use." Nothing has ever consumed the structured arrays.

Verified byte-for-byte on the real SAM payload with jq: 81/81 policy titles and bodies and 50/50 knowledge observations appear verbatim inside the rendered directives.

This PR stops emitting the two arrays. They remain as local variables feeding the formatters and the hasKnowledge/hasPolicies instruction switches.

Real SAM project: 166,814 → ~81,025 chars (−51%, ~21.4k tokens saved on every session bootstrap).

Critical implementation note: policy IDs

policyDirectives rendered - **{title}**: {content} with no id (0 of 81 policy ids appeared anywhere in it), while instructions[14] tells the agent to call update_policy/remove_policy — both of which require policyId. The id existed only in the array being removed.

formatPolicyDirectives now renders it inline: - **{title}** (id: {uuid}): {content}.

The id is rendered in FULL, not elided. The task brief suggested (id: 7d24e435…), but policies.ts:118,136 resolve with WHERE id = ? (exact match), so an abbreviated id would silently fail to address the row. Cost: +3,483 chars against 52,157 saved.

Deliberately not fixed here: observationId is required by update_knowledge/remove_knowledge/confirm_knowledge but has never been in the response — knowledgeContext mapped only entityName/entityType/observation/confidence, though the underlying SELECT o.* returns the id. So this PR loses nothing those tools could have used. Filed as tasks/backlog/2026-08-23-get-instructions-missing-observation-ids.md; fixing it means reshaping the ' | '-joined per-entity grouping, which would collide with in-flight sibling R3.

Rule 44 — consumer enumeration

Location	Kind	Action
instruction-tools.ts	only producer	arrays become locals, no longer emitted
apps/web/, packages/vm-agent/, tests, specs/, .claude/, apps/www/	—	no runtime consumer exists
tasks/archive/2026-04-26-policy-propagation-phase4.md	historical record	left alone
tasks/backlog/2026-04-13-knowledge-graph-test-coverage.md	unstarted criteria naming the removed field	updated to knowledgeDirectives

Independently re-verified by architecture-reviewer including packages/vm-agent/**/*.go and apps/web/src/**: the Go/web get_instructions hits all concern the injected system-reminder prompt text, not response parsing.

Coordination with in-flight siblings

origin/main was unchanged at push time, so this lands first as planned. architecture-reviewer confirmed via git merge-tree a guaranteed (mechanical, not design-level) conflict with R2 sam/add-lifecycle-controls-sam-jrnt7n on three spans. The merged template line should read:

`- **${item.title}** (id: ${item.id})${item.lifecycle}: ${item.content}`

Whoever rebases R2 should re-run this PR's renders ids in FULL... test, which asserts the exact (id: ${id}) string shape. R3 does not conflict — this diff never touches the knowledge block.

Validation

• pnpm lint — 0 errors (3 pre-existing apps/web warnings, untouched)
• pnpm typecheck — 19/19 tasks clean
• pnpm test — apps/api: 595 files, 8,037 tests, 0 failed, 0 collection errors (8,025 baseline + 12; now 14 after review fixes)
• Additional: pnpm build 9/9; pnpm check:fast 13/13 with 0 blocking type-boundary findings
• N/A — no sweep/cron/alarm candidate-selection change

Discriminating-test proof (rules 02/62): re-adding the two structured arrays turns exactly 5 of 14 tests red — the three "exactly once" body/title/observation tests, the "omits structured arrays" test, and the same-entity multi-observation test. Restored → 14/14 green. Verified twice (before and after the review fixes), and independently reproduced by test-engineer.

Note on reporting: a failed import shows up in vitest as 0 passed / 0 failed / success:false. Totals here were read per-file from the JSON reporter with an explicit assertionResults.length check, so a collection error cannot masquerade as a pass.

Staging Verification (REQUIRED for all code changes — merge-blocking)

• Staging deployment green — run 32648180754, conclusion success
• Live app verified via Playwright — app.sammy.party, token-login 200
• Existing workflows confirmed working — dashboard, /projects (16 listed), /settings all render at 375x667 and 1280x800; GET /health 200; 0 console errors at both viewports
• New feature/fix verified on staging — see evidence below
• N/A: no infra changes — does not touch packages/cloud-init/, packages/vm-agent/, scripts/deploy/, DNS, or TLS
• Mobile and desktop verification notes added (no UI change, but both viewports exercised)

Staging Verification Evidence

Measured through the real deployed Worker via POST https://api.sammy.party/mcp with a live MCP token read from staging KV — the exact code path an agent bootstraps through. Project 01KTKXZ4ZZAT6MJFXRW1ZTQ7RB seeded with 3 marked policies (one per category) + 1 observation; identical data measured either side of the deploy.

	BEFORE (pre-fix main)	AFTER (this branch)
total payload	6,025 chars	5,230 chars
knowledgeContext	177 chars, 1 item	ABSENT
policyContext	652 chars, 3 items	ABSENT
policyDirectives	481 chars	610 chars (+129 = the 3 inline ids)
occurrences of each body	2	1
full policy ids rendered	0 of 3	3 of 3

The absolute delta is small only because the fixture is small — fixed context/task/project/instructions overhead (~4,010 chars) dominates at that size. What was eliminated is the duplication, which scales with knowledge + policy volume: on the real SAM project (81 policies, 50 observations) that is 166,814 → ~81,025.

Management round-trip proven end-to-end — the decisive check, and exactly what an elided id would have broken:

1. Scraped c546f67b-… out of - **...** (id: ...) in the rendered markdown
2. update_policy with only that id → {"updated":true,...}
3. Fresh get_instructions → new text present, stale text gone
4. remove_policy × 3 → {"removed":true,...} each

Incidentally confirmed the filed observationId gap: removing the seeded observation required search_knowledge to obtain the id, because get_instructions still does not expose it.

Cleanup: all seeded data removed; payload returned to exactly the 4,010-char empty-path shape with zero R1VERIFY residue. No VMs or nodes were created (the MCP endpoint was exercised directly), so the zero-VMs-at-rest rule is respected.

UI Compliance Checklist

N/A: no UI changes — diff touches only apps/api/src/routes/mcp/instruction-tools.ts, one test file, and task markdown.

End-to-End Verification

• Data flow traced with code path citations
• Capability test exercises the complete happy path across system boundaries
• Assumptions verified against code, not assumed
• Gaps documented below

Data Flow Trace

1. Agent calls get_instructions (MCP tools/call)
   -> apps/api/src/index.ts:801  app.route('/mcp', mcpRoutes)
   -> apps/api/src/routes/mcp/index.ts:278  case 'get_instructions'

2. Handler retrieves knowledge + policies
   -> instruction-tools.ts:148  projectDataService.getAllHighConfidenceKnowledge()
   -> instruction-tools.ts:187  projectDataService.getActivePolicies()
       (both unchanged; both still wrapped in try/catch -> [])

3. Rendered to markdown — the SINGLE representation
   -> instruction-tools.ts:169  formatKnowledgeDirectives()
   -> instruction-tools.ts:202  formatPolicyDirectives()   <-- now interpolates item.id

4. Result object omits the structured arrays        <-- THE CHANGE
   -> instruction-tools.ts:289-297

5. Agent reads the id and acts on it
   -> update_policy / remove_policy
   -> durable-objects/project-data/policies.ts:118,136  WHERE id = ?  (exact match)

Step 5 is why the id must be full-length; it was verified live on staging, not just reasoned about.

Untested Gaps

No same-process integration test round-trips the rendered id through the real handleUpdatePolicy. formatPolicyDirectives does a literal ${item.id} interpolation with no transformation, so the id is unmodified by construction — and the round-trip was exercised end-to-end against the deployed staging Worker (evidence above), which is stronger than a mocked test. Raised by task-completion-validator as MEDIUM and resolved that way.

Post-Mortem

N/A: not a bug fix — this is a token/cost optimization (R1 of the token-optimization program, idea 01M0QGZQ15WE9DDQENGV6S9XZ5). No user-visible defect is being corrected, so no process fix is required. One pre-existing gap discovered during research was filed rather than silently inherited: tasks/backlog/2026-08-23-get-instructions-missing-observation-ids.md.

Specialist Review Evidence

• All local reviewers completed and findings addressed before merge
• N/A — no reviewer failed to complete, so no needs-human-review label needed

Reviewer	Status	Outcome
cloudflare-specialist	PASS	0 CRITICAL/HIGH. MCP JSON-RPC envelope unchanged and get_instructions declares no outputSchema, so no output contract is violated; DO RPC calls and both try/catch → [] fallbacks byte-for-byte unchanged; 0 new round-trips (rule 60). Proved (id: undefined) is impossible — parsePolicyRow requires v.string(), so a bad id throws upstream and the batch degrades to [] rather than rendering a corrupt line. 2 LOW informational notes, no in-branch action.
architecture-reviewer	ADDRESSED	0 CRITICAL/HIGH. Independently re-ran the rule-44 enumeration (incl. vm-agent Go + web) — matched exactly. Endorsed the prose-id design: list_policies/get_policy already provide structured access, so a policyIds array would be a redundant fourth representation and a correlatable {id,title}[] would cost ~2x the inline form. MEDIUM "add a comment so nobody re-adds the array" applied in 62e3bcba1. MEDIUM R2 merge-conflict note is informational (see Coordination above).
test-engineer	ADDRESSED	0 CRITICAL/HIGH. Independently reproduced the discriminating check. Real gaps fixed in 62e3bcba1: missing liveness assertion on the absence test (rule 62 req 5); no coverage anywhere in the repo of the same-entity multi-observation `'
task-completion-validator	ADDRESSED	Returned FAIL with 1 CRITICAL — and was right. The task file had been archived with a blanket sed that ticked every box including the staging criterion before staging had run, and archiving preceded the validator, violating rule 09. Fixed in 62e3bcba1: moved back to tasks/active/, un-ticked the two non-empirical criteria, relabelled the Outcome section. Both MEDIUMs (projected-not-measured AFTER figure; no live id round-trip) are now resolved by the staging evidence above; task archived in 754bcf0bf only after that evidence existed.

Not run, with reason: go-specialist (no Go), ui-ux-specialist (no UI), security-auditor (no auth/credential/token code), env-validator (no env vars), doc-sync-validator (grep confirmed no doc anywhere references these fields), constitution-validator (no hardcoded values; the (id: ...) format string is presentation, not configuration).

Exceptions

• Scope: task file committed to the feature branch rather than main as /do Phase 1 prescribes.
• Rationale: branch protection rejects direct pushes to main (Required status check "Durable Object Workers" is expected). Also the safer default per CLAUDE.md's "never commit directly to main."
• Expiration: n/a — permanent, this is the correct behaviour.

Agent Preflight (Required)

• Preflight completed before code changes

Classification

• external-api-change
• cross-component-change
• business-logic-change
• public-surface-change
• docs-sync-change
• security-sensitive-change
• ui-change
• infra-change

public-surface-change: the MCP get_instructions response shape changes for every agent. business-logic-change: how policy identifiers reach the agent changes.

External References

N/A: no external API involved. Sources were in-repo and empirical — the live get_instructions payload (measured with jq), .claude/rules/44 (enumerate every consumer), .claude/rules/02/62 (discriminating tests), and library research doc /engineering/research/token-optimization-research.md §3.1 and §8/R1.

Codebase Impact Analysis

apps/api/src/routes/mcp/instruction-tools.ts (only runtime file: −2 emitted fields, +1 rendered id, comments), apps/api/tests/unit/routes/mcp-instruction-payload-dedup.test.ts (new, 14 tests), 3 task markdown files. No packages/ change, no apps/web change, no schema/migration, no new dependency.

Documentation & Specs

apps/www/src/content/docs/docs/architecture/overview.md — added an Agent Bootstrap Payload (get_instructions) subsection under Agent Configuration Layers. It documents that knowledge and policies are delivered as rendered markdown only, that there is deliberately no second structured copy (and why the knowledgeContext/policyContext arrays were removed), that list_policies/get_policy and search_knowledge/get_project_knowledge are the machine-readable paths, and that policy lines carry full untruncated ids because WHERE id = ? is an exact match. It also records that observations still lack observationId in this payload.

No prior doc described this response shape — grep across apps/www/, specs/, and .claude/ found zero references to knowledgeContext/policyContext, and the get_instructions tool description does not mention either field. The one stale mention (acceptance criteria in an unstarted backlog task) is also updated in this PR.

Constitution & Risk Check

Principle XI (no hardcoded values): no new URL, timeout, or limit. The (id: ...) template is presentation, not configuration.

Risks / tradeoffs

1. Removing a field others might depend on — mitigated by the rule-44 enumeration, independently re-verified by a second reviewer.
2. Elided id would break policy management — the reason full UUIDs are rendered; proven live on staging by scraping an id and mutating with it.
3. Prose id vs structured field — accepted deliberately; list_policies/get_policy remain the structured path, and a comment in the code prevents a future "fix" from re-adding the array.
4. R2 merge conflict — guaranteed but mechanical; the resolved line is given above.

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Merge to main and production ship for this work were explicitly authorized by Raphaël (2026-08-23), recorded in the SAM task description for 01M0QHHVEQY11VC37Y29B6GGY4.

🤖 Generated with Claude Code

[codspeed-hq]

Merging this PR will not alter performance

✅ 6 untouched benchmarks

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_{Comparing sam/remove-duplicated-structured-arrays-b6ggy4 (4b8c2e4) with main (b36f235)}

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud