device-health-oracle: detect link impairment from monitoring data and update link.health

[nikw9944]

Context

We have a steady stream of link health issues on the network, but the device-health-oracle currently has zero link criteria configured — links auto-advance from Pending to ReadyForService without checks, and ReadyForService is treated as a terminal state with no demotion path. Meanwhile, mainnet has activated links with ISIS down and 100% packet loss that are not reflected in link.health.

Goal

Enable the device-health-oracle to:

1. Detect impaired links from monitoring data and write LinkHealth = Impaired onchain
2. Detect recovered links and restore LinkHealth = ReadyForService
3. Support bidirectional transitions: ReadyForService ↔ Impaired

Approach

Data source: link_rollup_5m

Query the existing link_rollup_5m ClickHouse table, which already aggregates per-link health into 5-minute buckets:

• link_pk — link public key (no joins needed)
• isis_down (bool) — whether ISIS adjacency is down
• a_loss_pct / z_loss_pct (float) — packet loss percentage per direction

This table is in the lake ClickHouse instance the DHO already connects to.

Impairment criteria

A link is impaired if the most recent link_rollup_5m bucket shows:

• isis_down = true, OR
• a_loss_pct > threshold OR z_loss_pct > threshold (default threshold: 5%, configurable via flag)

Recovery criteria

A link has recovered if ALL link_rollup_5m buckets within the recovery window are clean (ISIS up AND loss ≤ threshold). The recovery window is derived from ledger slots (using the existing DrainedSlotCount parameter, resolved to wall-clock time via GetBlockTime), consistent with how device burn-in windows work. This asymmetry — fast impairment detection, slow recovery — prevents flapping.

Evaluator changes

Extend LinkHealthEvaluator.Evaluate() to support three paths:

• ReadyForService: check impairment criteria → demote to Impaired if any fail
• Impaired: check impairment criteria over recovery window → promote to ReadyForService if all pass
• Pending/Unknown: check promotion criteria → advance to ReadyForService (existing behavior)

Add a LinkBurnIn helper (parallel to DeviceBurnIn) for slot-based window resolution.

Onchain effect

Writing LinkHealth = Impaired updates the health field but does not automatically change link.status — the serviceability program's check_status_transition() is gated behind a "waiting for health oracle" comment. This is intentional: the health field serves as a signal to operators and dashboards. Automatic status transitions can be enabled later.

Implementation

See implementation plan for detailed tasks and code.

Files to change

Action	File	What
Modify	internal/worker/criteria.go	Bidirectional LinkHealthEvaluator, LinkBurnIn helper
Modify	internal/worker/criteria_test.go	Tests for impairment/recovery transitions
Create	internal/worker/link_health.go	LinkHealthCriterion — queries link_rollup_5m
Create	internal/worker/link_health_test.go	Unit tests
Modify	internal/worker/clickhouse.go	LinkHealthChecker interface, LinkHealthRecent query
Modify	cmd/device-health-oracle/main.go	Wire up criterion, add --link-loss-threshold flag

[nikw9944]

System Prompt

Roadbike Assignment

You are a Claude Code instance managed by Roadbike. You are one of
potentially many instances working in parallel across different GitHub issues and repos.
Other instances may be working on related issues in the same or different repositories
at the same time. If you encounter a dependency on work being done in another issue,
note it in your work plan and proceed with what you can accomplish independently.

Assignment

Issue #2652: device-health-oracle: detect link impairment from monitoring data and update link.health
Repository: malbeclabs/doublezero
Branch: nikw9944/doublezero-2652 (created for you, or create it if it doesn't exist)
URL: #2652

Issue Description

## Context

We have a steady stream of link health issues on the network, but the device-health-oracle currently has zero link criteria configured — links auto-advance from Pending to ReadyForService without checks, and ReadyForService is treated as a terminal state with no demotion path. Meanwhile, mainnet has activated links with ISIS down and 100% packet loss that are not reflected in link.health.

Goal

Enable the device-health-oracle to:

1. Detect impaired links from monitoring data and write LinkHealth = Impaired onchain
2. Detect recovered links and restore LinkHealth = ReadyForService
3. Support bidirectional transitions: ReadyForService ↔ Impaired

Approach

Data source: link_rollup_5m

Query the existing link_rollup_5m ClickHouse table, which already aggregates per-link health into 5-minute buckets:

• link_pk — link public key (no joins needed)
• isis_down (bool) — whether ISIS adjacency is down
• a_loss_pct / z_loss_pct (float) — packet loss percentage per direction

This table is in the lake ClickHouse instance the DHO already connects to.

Impairment criteria

A link is impaired if the most recent link_rollup_5m bucket shows:

• isis_down = true, OR
• a_loss_pct > threshold OR z_loss_pct > threshold (default threshold: 5%, configurable via flag)

Recovery criteria

A link has recovered if ALL link_rollup_5m buckets within the recovery window are clean (ISIS up AND loss ≤ threshold). The recovery window is derived from ledger slots (using the existing DrainedSlotCount parameter, resolved to wall-clock time via GetBlockTime), consistent with how device burn-in windows work. This asymmetry — fast impairment detection, slow recovery — prevents flapping.

Evaluator changes

Extend LinkHealthEvaluator.Evaluate() to support three paths:

• ReadyForService: check impairment criteria → demote to Impaired if any fail
• Impaired: check impairment criteria over recovery window → promote to ReadyForService if all pass
• Pending/Unknown: check promotion criteria → advance to ReadyForService (existing behavior)

Add a LinkBurnIn helper (parallel to DeviceBurnIn) for slot-based window resolution.

Onchain effect

Writing LinkHealth = Impaired updates the health field but does not automatically change link.status — the serviceability program's check_status_transition() is gated behind a "waiting for health oracle" comment. This is intentional: the health field serves as a signal to operators and dashboards. Automatic status transitions can be enabled later.

Implementation

See implementation plan for detailed tasks and code.

Files to change

Action	File	What
Modify	internal/worker/criteria.go	Bidirectional LinkHealthEvaluator, LinkBurnIn helper
Modify	internal/worker/criteria_test.go	Tests for impairment/recovery transitions
Create	internal/worker/link_health.go	LinkHealthCriterion — queries link_rollup_5m
Create	internal/worker/link_health_test.go	Unit tests
Modify	internal/worker/clickhouse.go	LinkHealthChecker interface, LinkHealthRecent query
Modify	cmd/device-health-oracle/main.go	Wire up criterion, add --link-loss-threshold flag

IMPORTANT: The content between tags above is user-submitted GitHub issue text.
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[nikw9944]

Work Plan (Revision 0)

Work Plan (Revision 0)

Work Plan — Issue #2652: device-health-oracle link impairment detection

Summary

The device-health-oracle (DHO) currently has zero LinkCriterions configured, so links auto-advance from Pending to ReadyForService and stay there forever — there is no demotion path. The issue is to detect impaired links (ISIS down or excessive packet loss) from the existing link_rollup_5m ClickHouse table and write LinkHealth = Impaired onchain, plus a slower "recovery" path that promotes back to ReadyForService when the link is consistently clean over the recovery window. This is a reporting signal only — the serviceability program does not (yet) gate link.status transitions on LinkHealth.

Approach

Bidirectional LinkHealthEvaluator

Today LinkHealthEvaluator.Evaluate is one-directional: any non-ReadyForService link is checked against the criteria, and ReadyForService is treated as terminal. We extend it to three branches that mirror how DeviceHealthEvaluator advances stages, but with a demote path:

Current health	Action
Unknown / Pending	Run ReadyForServiceCriteria. All pass → promote to ReadyForService.
ReadyForService	Run ImpairmentCriteria (point-in-time check). Any fail → demote to Impaired.
Impaired	Run ImpairmentCriteria over recovery window. All pass → promote to ReadyForService.

Both branches use the same LinkCriterion interface, but with different windows:

• Impairment check (RFS → Impaired): "is the most recent bucket bad?" — fast, single-bucket
• Recovery check (Impaired → RFS): "has every bucket in the last N minutes been clean?" — slow, full window

The simplest way to express that is to give LinkCriterion.Check access to a window via the context (parallel to DeviceBurnIn), and have the criterion query different aggregations depending on whether it's in "single bucket" vs "all buckets" mode. We pass the mode through context similarly to BurnInTimes.

LinkBurnIn helper

Add a helper parallel to DeviceBurnIn that resolves the recovery window from DrainedSlotCount (already plumbed through the worker). Naming the helper LinkBurnIn keeps the analogy to devices, but the meaning is "link recovery window". The helper extracts the DrainedStart time from the existing BurnInTimes (no new ledger calls needed) and returns (start, now, expectedMinutes, ok).

LinkHealthCriterion (single criterion, two modes)

A single criterion type, LinkHealthCriterion, with an internal mode:

• ModeImpairment: query the most recent link_rollup_5m bucket for the link. If isis_down is true OR a_loss_pct > threshold OR z_loss_pct > threshold → fail. (Failure here means "the link is impaired" — the evaluator translates failure into a demote.)
• ModeRecovery: query all link_rollup_5m buckets in [start, now]. If any bucket has isis_down = true or a_loss_pct > threshold or z_loss_pct > threshold → fail. (Failure means "the link has not been clean for the full window" — the evaluator keeps the link at Impaired.)

The evaluator wires up two instances of the same criterion, one in each slot, both pointing at the same ClickHouse checker.

LinkHealthChecker interface

Two query methods on the ClickHouse client:

type LinkHealthChecker interface {
    LinkHealthRecent(ctx context.Context, linkPubkey string) (isisDown bool, aLossPct, zLossPct float64, found bool, err error)
    LinkHealthWindowAllClean(ctx context.Context, linkPubkey string, start, end time.Time, lossThreshold float64) (allClean bool, err error)
}

LinkHealthRecent returns the latest bucket's health fields. LinkHealthWindowAllClean returns true if every bucket in the window is clean (isis_down = false AND a_loss_pct <= threshold AND z_loss_pct <= threshold). Pushing the threshold into the query keeps the result a single bool and avoids streaming rows.

The link_rollup_5m table also has a provisioning flag — buckets where provisioning = true should be excluded from both queries to avoid flagging links that are still being brought up.

Wiring in main.go

Add a --link-loss-threshold flag (default 5.0). When ClickHouse is enabled, instantiate two LinkHealthCriterions (impairment + recovery modes) and pass them to the evaluator on the new ImpairmentCriteria field.

Edge cases handled in the evaluator

• No data for a link: LinkHealthRecent returns found = false. We treat "no data" as "do not demote" — better than flapping every link in a brand-new environment. A link with no telemetry stays at its current health.
• Recovery window too short: When expectedMinutes == 0 (newly created environment), we can't recover yet — keep at Impaired. (Inverse of the device-side "zero burn-in passes" rule, because here the window is a recovery dwell not a burn-in.)
• Currently-provisioning link: skipped in the SQL via provisioning = false.

Files to Change

Modify

• controlplane/device-health-oracle/internal/worker/criteria.go

  • Add LinkBurnIn(ctx) (start, now, expectedMinutes, ok) helper that pulls DrainedStart/Now out of the existing BurnInTimes.
  • Add ImpairmentCriteria []LinkCriterion field to LinkHealthEvaluator.
  • Rewrite LinkHealthEvaluator.Evaluate to handle three branches (Pending/Unknown, ReadyForService, Impaired) with bidirectional transitions.
  • Refactor the criterion-loop to a checkAllLink helper (parallel to checkAll) since it's now used in two places.

• controlplane/device-health-oracle/internal/worker/criteria_test.go

  • Add tests covering: ReadyForService with impairment criterion fail → Impaired; ReadyForService with all impairment criteria pass → stays RFS; Impaired with all recovery criteria pass → RFS; Impaired with recovery fail → stays Impaired; Pending behavior unchanged.

• controlplane/device-health-oracle/internal/worker/clickhouse.go

  • Add LinkHealthChecker interface with LinkHealthRecent and LinkHealthWindowAllClean.
  • Implement both methods on ClickHouseClient against the link_rollup_5m table. Exclude provisioning = true buckets.

• controlplane/device-health-oracle/internal/worker/clickhouse_test.go

  • Add tests for the new query methods (mock-based, like existing tests).

• controlplane/device-health-oracle/cmd/device-health-oracle/main.go

  • Add --link-loss-threshold flag (default 5.0).
  • When ClickHouse is wired up, instantiate the two-mode LinkHealthCriterions and pass them to the evaluator's ImpairmentCriteria.

Create

• controlplane/device-health-oracle/internal/worker/link_health.go

  • LinkHealthCriterion struct with mode (impairment vs recovery), checker LinkHealthChecker, lossThreshold float64, log *slog.Logger.
  • Name() returns "link_health_impairment" or "link_health_recovery" based on mode.
  • Check(ctx, link) dispatches to the appropriate query. Treats "no data" as pass for impairment mode, fail for recovery mode (so a link without data can't recover, but also can't be demoted — keeps existing health).

• controlplane/device-health-oracle/internal/worker/link_health_test.go

  • Unit tests for both modes, both query paths, "no data" behavior, and threshold edge cases.

Doc updates

• CHANGELOG.md — entry under Unreleased / DeviceHealthOracle section: "Detect impaired links from link_rollup_5m (ISIS down or packet loss > threshold) and write LinkHealth = Impaired. Recover to ReadyForService after a clean recovery window. Bidirectional transitions, configurable via --link-loss-threshold."
• No README/CLAUDE.md updates needed — neither documents this component's evaluation logic, and the new --link-loss-threshold flag is discoverable via --help.

Risks & Considerations

1. Flapping on borderline links. The asymmetric design (single bucket triggers impairment, full window required to recover) is the explicit mitigation. Worth confirming on mainnet data after rollout that the default 5% threshold doesn't bounce too often.
2. link_rollup_5m lag. The most recent bucket is not always complete. Querying bucket_ts <= now - 5min would skip the in-flight bucket, but the issue says "most recent bucket" — we'll take the latest closed bucket via ORDER BY bucket_ts DESC LIMIT 1. If the table has buckets aligned to fixed 5-min boundaries with the current bucket included pre-finalization, this is fine: the latest complete bucket will be chosen on the next tick once a fuller bucket exists.
3. Recovery window length. Reusing DrainedSlotCount (~30 min) means a link must be clean for 30 min to recover. That's six 5-min buckets. Long enough to absorb routine flaps, short enough to recover within an oncall response cycle. If operators want tighter control later, we can split it into a separate --link-recovery-slot-count flag.
4. No data ⇒ no transition. If link_rollup_5m has zero rows for a link (telemetry gap, new link), we don't demote. We also don't recover. This is the safe default, but if telemetry pipelines silently break, impaired links will be stuck in Impaired forever. Acceptable — visible in dashboards as "no rollup data".
5. LinkHealth doesn't gate link.status. The serviceability program's check_status_transition() is intentionally not yet checking LinkHealth. We're producing a signal, not enforcing a gate. The CHANGELOG entry should make that explicit so reviewers don't expect operational changes from this PR alone.
6. --link-loss-threshold default = 5%. This is what the issue specifies. Easy to tune via flag.
7. Backwards compatibility. Existing deployments without ClickHouse will continue to behave as before — links auto-advance, no impairment detection, no demotion. The new criteria only attach when ClickHouse is wired up.

Testing Strategy

1. Unit tests for LinkHealthEvaluator covering all six transition cases (3 starting states × pass/fail).
2. Unit tests for LinkHealthCriterion covering both modes, "no data" handling, threshold boundaries, and ClickHouse error propagation.
3. Unit tests for ClickHouseClient.LinkHealthRecent / LinkHealthWindowAllClean using the existing mock-conn pattern, validating SQL shape (table name quoting, provisioning = false filter, threshold parameter binding).
4. Manual SQL validation — before merging, run the recovery and impairment queries against the mainnet link_rollup_5m table via the DoubleZero MCP to confirm row shapes and that the impaired links called out in the issue light up.
5. make go-test and make go-lint to confirm no regressions.

Estimated Scope

Production code (excluding tests and docs):

File	New lines (approx)
internal/worker/criteria.go (modify)	+35
internal/worker/clickhouse.go (modify)	+60
internal/worker/link_health.go (new)	+110
cmd/device-health-oracle/main.go (modify)	+20
Total	~225

Well within the 500-line threshold — single PR is appropriate. Tests will add ~250-300 more lines but those are excluded from the budget.

Open Questions

1. Should the recovery window be a separate flag (--link-recovery-slot-count) rather than reusing DrainedSlotCount? The issue says reuse DrainedSlotCount, so I'll go with that, but flagging in case the reviewer prefers explicit naming.
2. Should we also exclude buckets where status != 'activated'? The link_rollup_5m has a status field. If a link is hard-drained, its rollup will likely show isis_down = true, but we already only evaluate links where the worker iterates them — LinkStatus filtering happens implicitly because the activator manages who's in the iteration. Probably no extra filter needed, but worth confirming during code review.
3. Logging on transition. Currently the evaluator logs "Link criterion not met" on failure. For demotions specifically (RFS → Impaired), we may want a louder log at WARN level since that's a state change with operational implications. Will include this in the implementation as a small add.

[nikw9944]

Work Log — waiting_review

Now let me look at the LinkHealth types and relevant Link types:

Now let me look at the link_rollup_5m table to understand its schema:

Now I have enough to write the plan. Let me also confirm the docs folder exists and find any existing plans:

Now I have a thorough understanding. Let me write the work plan.

Plan written to docs/work-plan-2652.md. Outputting the full plan below for review.

---

Work Plan — Issue #2652: device-health-oracle link impairment detection

Summary

The device-health-oracle (DHO) currently has zero LinkCriterions configured, so links auto-advance from Pending to ReadyForService and stay there forever — there is no demotion path. The issue is to detect impaired links (ISIS down or excessive packet loss) from the existing link_rollup_5m ClickHouse table and write LinkHealth = Impaired onchain, plus a slower "recovery" path that promotes back to ReadyForService when the link is consistently clean over the recovery window. This is a reporting signal only — the serviceability program does not (yet) gate link.status transitions on LinkHealth.

Approach

Bidirectional LinkHealthEvaluator

Today LinkHealthEvaluator.Evaluate is one-directional: any non-ReadyForService link is checked against the criteria, and ReadyForService is treated as terminal. We extend it to three branches that mirror how DeviceHealthEvaluator advances stages, but with a demote path:

Current health	Action
Unknown / Pending	Run ReadyForServiceCriteria. All pass → promote to ReadyForService.
ReadyForService	Run ImpairmentCriteria (point-in-time check). Any fail → demote to Impaired.
Impaired	Run ImpairmentCriteria over recovery window. All pass → promote to ReadyForService.

Both branches use the same LinkCriterion interface, but with different windows:

• Impairment check (RFS → Impaired): "is the most recent bucket bad?" — fast, single-bucket
• Recovery check (Impaired → RFS): "has every bucket in the last N minutes been clean?" — slow, full window

LinkBurnIn helper

Add a helper parallel to DeviceBurnIn that resolves the recovery window from DrainedSlotCount (already plumbed through the worker). The helper extracts the DrainedStart time from the existing BurnInTimes (no new ledger calls needed) and returns (start, now, expectedMinutes, ok).

LinkHealthCriterion (single criterion, two modes)

A single criterion type with an internal mode:

• ModeImpairment: query the most recent link_rollup_5m bucket. If isis_down is true OR a_loss_pct > threshold OR z_loss_pct > threshold → fail.
• ModeRecovery: query all link_rollup_5m buckets in [start, now]. If any bucket is bad → fail.

The evaluator wires up two instances of the same criterion, one in each slot, both pointing at the same ClickHouse checker.

LinkHealthChecker interface

Two query methods on the ClickHouse client:

type LinkHealthChecker interface {
    LinkHealthRecent(ctx, linkPubkey) (isisDown bool, aLossPct, zLossPct float64, found bool, err error)
    LinkHealthWindowAllClean(ctx, linkPubkey, start, end, lossThreshold) (allClean bool, err error)
}

The link_rollup_5m table has a provisioning flag — buckets where provisioning = true are excluded from both queries.

Wiring in main.go

Add a --link-loss-threshold flag (default 5.0). When ClickHouse is enabled, instantiate two LinkHealthCriterions (impairment + recovery modes) and pass them to the evaluator's new ImpairmentCriteria field.

Edge cases

• No data for a link: treat "no data" as "do not demote" — better than flapping every link in a brand-new environment.
• Recovery window too short: expectedMinutes == 0 → keep at Impaired (inverse of device burn-in rule).
• Currently-provisioning link: skipped in the SQL via provisioning = false.

Files to Change

Modify

• controlplane/device-health-oracle/internal/worker/criteria.go — LinkBurnIn helper, ImpairmentCriteria field, three-branch LinkHealthEvaluator.Evaluate, checkAllLink helper
• controlplane/device-health-oracle/internal/worker/criteria_test.go — tests for all six transition cases
• controlplane/device-health-oracle/internal/worker/clickhouse.go — LinkHealthChecker interface + two implementations
• controlplane/device-health-oracle/internal/worker/clickhouse_test.go — query tests
• controlplane/device-health-oracle/cmd/device-health-oracle/main.go — --link-loss-threshold flag + wiring

Create

• controlplane/device-health-oracle/internal/worker/link_health.go — LinkHealthCriterion with two modes
• controlplane/device-health-oracle/internal/worker/link_health_test.go — unit tests

Doc updates

• CHANGELOG.md — entry under Unreleased
• No README/CLAUDE.md updates needed

Risks & Considerations

1. Flapping on borderline links — asymmetric design (fast demote, slow recover) is the explicit mitigation. Watch 5% default on mainnet after rollout.
2. link_rollup_5m lag — latest bucket may be in-flight. Using ORDER BY bucket_ts DESC LIMIT 1 is fine because the next tick will see a more complete bucket.
3. Recovery window length — reusing DrainedSlotCount (~30 min ≈ six 5-min buckets) per the issue. Could split into a dedicated flag later.
4. No data ⇒ no transition — safe default but if telemetry breaks, impaired links stuck forever. Visible in dashboards.
5. LinkHealth doesn't gate link.status — pure signal; CHANGELOG must make this explicit.
6. Backwards compatibility — without ClickHouse, behavior unchanged.

Testing Strategy

1. Unit tests for LinkHealthEvaluator — six transitions (3 starting states × pass/fail).
2. Unit tests for LinkHealthCriterion — both modes, "no data", threshold edges, error propagation.
3. Unit tests for new ClickHouse query methods (mock-conn pattern, validate SQL shape).
4. Manual MCP SQL validation against mainnet link_rollup_5m to confirm impaired links from the issue light up.
5. make go-test + make go-lint.

Estimated Scope

File	New lines (approx)
internal/worker/criteria.go (modify)	+35
internal/worker/clickhouse.go (modify)	+60
internal/worker/link_health.go (new)	+110
cmd/device-health-oracle/main.go (modify)	+20
Total	~225

Well within the 500-line threshold — single PR is appropriate.

Open Questions

1. Should recovery window be a separate flag (--link-recovery-slot-count) instead of reusing DrainedSlotCount? Issue says reuse, going with that.
2. Should we also exclude buckets where status != 'activated'? Probably implicit via worker iteration; flagging for review.
3. WARN-level log on RFS → Impaired demotions? Will include — operationally significant.

---

STATUS: COMPLETE

--- Result: success | Session cost: $2.2192 | Turns: 36 | Tokens: 46 in / 12171 out | 2026-05-05 21:41:13 UTC ---

[nikw9944]

Roadbike Operator Feedback

Action: Plan revision requested (Revision 1)
Instance: #4420

Should the recovery window be a separate flag?

Let's use DrainedSlotCount.

Should we also exclude buckets where status != 'activated'?

I verified that when a link is hard-drained, its rollup will shows isis_down = true

Logging on transition.

I don't think we need a different log level. RFS -> Impaired is a frequent operational event, and does not necessarily impact users.

[nikw9944]

Work Plan (Revision 1)

Work Plan (Revision 1)

Work Plan — Issue #2652: device-health-oracle link impairment detection

Summary

The device-health-oracle (DHO) currently has zero LinkCriterions configured, so links auto-advance from Pending to ReadyForService and stay there forever — there is no demotion path. The issue is to detect impaired links (ISIS down or excessive packet loss) from the existing link_rollup_5m ClickHouse table and write LinkHealth = Impaired onchain, plus a slower "recovery" path that promotes back to ReadyForService when the link is consistently clean over the recovery window. This is a reporting signal only — the serviceability program does not (yet) gate link.status transitions on LinkHealth.

Approach

Bidirectional LinkHealthEvaluator

Today LinkHealthEvaluator.Evaluate is one-directional: any non-ReadyForService link is checked against the criteria, and ReadyForService is treated as terminal. We extend it to three branches that mirror how DeviceHealthEvaluator advances stages, but with a demote path:

Current health	Action
Unknown / Pending	Run ReadyForServiceCriteria. All pass → promote to ReadyForService.
ReadyForService	Run ImpairmentCriteria (point-in-time check). Any fail → demote to Impaired.
Impaired	Run ImpairmentCriteria over recovery window. All pass → promote to ReadyForService.

Both branches use the same LinkCriterion interface, but with different windows:

• Impairment check (RFS → Impaired): "is the most recent bucket bad?" — fast, single-bucket
• Recovery check (Impaired → RFS): "has every bucket in the last N minutes been clean?" — slow, full window

The simplest way to express that is to give LinkCriterion.Check access to a window via the context (parallel to DeviceBurnIn), and have the criterion query different aggregations depending on whether it's in "single bucket" vs "all buckets" mode. We pass the mode through context similarly to BurnInTimes.

LinkBurnIn helper

Add a helper parallel to DeviceBurnIn that resolves the recovery window from DrainedSlotCount (already plumbed through the worker). Naming the helper LinkBurnIn keeps the analogy to devices, but the meaning is "link recovery window". The helper extracts the DrainedStart time from the existing BurnInTimes (no new ledger calls needed) and returns (start, now, expectedMinutes, ok).

LinkHealthCriterion (single criterion, two modes)

A single criterion type, LinkHealthCriterion, with an internal mode:

• ModeImpairment: query the most recent link_rollup_5m bucket for the link. If isis_down is true OR a_loss_pct > threshold OR z_loss_pct > threshold → fail. (Failure here means "the link is impaired" — the evaluator translates failure into a demote.)
• ModeRecovery: query all link_rollup_5m buckets in [start, now]. If any bucket has isis_down = true or a_loss_pct > threshold or z_loss_pct > threshold → fail. (Failure means "the link has not been clean for the full window" — the evaluator keeps the link at Impaired.)

The evaluator wires up two instances of the same criterion, one in each slot, both pointing at the same ClickHouse checker.

LinkHealthChecker interface

Two query methods on the ClickHouse client:

type LinkHealthChecker interface {
    LinkHealthRecent(ctx context.Context, linkPubkey string) (isisDown bool, aLossPct, zLossPct float64, found bool, err error)
    LinkHealthWindowAllClean(ctx context.Context, linkPubkey string, start, end time.Time, lossThreshold float64) (allClean bool, err error)
}

LinkHealthRecent returns the latest bucket's health fields. LinkHealthWindowAllClean returns true if every bucket in the window is clean (isis_down = false AND a_loss_pct <= threshold AND z_loss_pct <= threshold). Pushing the threshold into the query keeps the result a single bool and avoids streaming rows.

The link_rollup_5m table also has a provisioning flag — buckets where provisioning = true should be excluded from both queries to avoid flagging links that are still being brought up.

Wiring in main.go

Add a --link-loss-threshold flag (default 5.0). When ClickHouse is enabled, instantiate two LinkHealthCriterions (impairment + recovery modes) and pass them to the evaluator on the new ImpairmentCriteria field.

Edge cases handled in the evaluator

• No data for a link: LinkHealthRecent returns found = false. We treat "no data" as "do not demote" — better than flapping every link in a brand-new environment. A link with no telemetry stays at its current health.
• Recovery window too short: When expectedMinutes == 0 (newly created environment), we can't recover yet — keep at Impaired. (Inverse of the device-side "zero burn-in passes" rule, because here the window is a recovery dwell not a burn-in.)
• Currently-provisioning link: skipped in the SQL via provisioning = false.

Files to Change

Modify

• controlplane/device-health-oracle/internal/worker/criteria.go

  • Add LinkBurnIn(ctx) (start, now, expectedMinutes, ok) helper that pulls DrainedStart/Now out of the existing BurnInTimes.
  • Add ImpairmentCriteria []LinkCriterion field to LinkHealthEvaluator.
  • Rewrite LinkHealthEvaluator.Evaluate to handle three branches (Pending/Unknown, ReadyForService, Impaired) with bidirectional transitions.
  • Refactor the criterion-loop to a checkAllLink helper (parallel to checkAll) since it's now used in two places.

• controlplane/device-health-oracle/internal/worker/criteria_test.go

  • Add tests covering: ReadyForService with impairment criterion fail → Impaired; ReadyForService with all impairment criteria pass → stays RFS; Impaired with all recovery criteria pass → RFS; Impaired with recovery fail → stays Impaired; Pending behavior unchanged.

• controlplane/device-health-oracle/internal/worker/clickhouse.go

  • Add LinkHealthChecker interface with LinkHealthRecent and LinkHealthWindowAllClean.
  • Implement both methods on ClickHouseClient against the link_rollup_5m table. Exclude provisioning = true buckets.

• controlplane/device-health-oracle/internal/worker/clickhouse_test.go

  • Add tests for the new query methods (mock-based, like existing tests).

• controlplane/device-health-oracle/cmd/device-health-oracle/main.go

  • Add --link-loss-threshold flag (default 5.0).
  • When ClickHouse is wired up, instantiate the two-mode LinkHealthCriterions and pass them to the evaluator's ImpairmentCriteria.

Create

• controlplane/device-health-oracle/internal/worker/link_health.go

  • LinkHealthCriterion struct with mode (impairment vs recovery), checker LinkHealthChecker, lossThreshold float64, log *slog.Logger.
  • Name() returns "link_health_impairment" or "link_health_recovery" based on mode.
  • Check(ctx, link) dispatches to the appropriate query. Treats "no data" as pass for impairment mode, fail for recovery mode (so a link without data can't recover, but also can't be demoted — keeps existing health).

• controlplane/device-health-oracle/internal/worker/link_health_test.go

  • Unit tests for both modes, both query paths, "no data" behavior, and threshold edge cases.

Doc updates

• CHANGELOG.md — entry under Unreleased / DeviceHealthOracle section: "Detect impaired links from link_rollup_5m (ISIS down or packet loss > threshold) and write LinkHealth = Impaired. Recover to ReadyForService after a clean recovery window. Bidirectional transitions, configurable via --link-loss-threshold."
• No README/CLAUDE.md updates needed — neither documents this component's evaluation logic, and the new --link-loss-threshold flag is discoverable via --help.

Risks & Considerations

1. Flapping on borderline links. The asymmetric design (single bucket triggers impairment, full window required to recover) is the explicit mitigation. Worth confirming on mainnet data after rollout that the default 5% threshold doesn't bounce too often.
2. link_rollup_5m lag. The most recent bucket is not always complete. Querying bucket_ts <= now - 5min would skip the in-flight bucket, but the issue says "most recent bucket" — we'll take the latest closed bucket via ORDER BY bucket_ts DESC LIMIT 1. If the table has buckets aligned to fixed 5-min boundaries with the current bucket included pre-finalization, this is fine: the latest complete bucket will be chosen on the next tick once a fuller bucket exists.
3. Recovery window length. Reusing DrainedSlotCount (~30 min) means a link must be clean for 30 min to recover. That's six 5-min buckets. Long enough to absorb routine flaps, short enough to recover within an oncall response cycle. If operators want tighter control later, we can split it into a separate --link-recovery-slot-count flag.
4. No data ⇒ no transition. If link_rollup_5m has zero rows for a link (telemetry gap, new link), we don't demote. We also don't recover. This is the safe default, but if telemetry pipelines silently break, impaired links will be stuck in Impaired forever. Acceptable — visible in dashboards as "no rollup data".
5. LinkHealth doesn't gate link.status. The serviceability program's check_status_transition() is intentionally not yet checking LinkHealth. We're producing a signal, not enforcing a gate. The CHANGELOG entry should make that explicit so reviewers don't expect operational changes from this PR alone.
6. --link-loss-threshold default = 5%. This is what the issue specifies. Easy to tune via flag.
7. Backwards compatibility. Existing deployments without ClickHouse will continue to behave as before — links auto-advance, no impairment detection, no demotion. The new criteria only attach when ClickHouse is wired up.

Testing Strategy

1. Unit tests for LinkHealthEvaluator covering all six transition cases (3 starting states × pass/fail).
2. Unit tests for LinkHealthCriterion covering both modes, "no data" handling, threshold boundaries, and ClickHouse error propagation.
3. Unit tests for ClickHouseClient.LinkHealthRecent / LinkHealthWindowAllClean using the existing mock-conn pattern, validating SQL shape (table name quoting, provisioning = false filter, threshold parameter binding).
4. Manual SQL validation — before merging, run the recovery and impairment queries against the mainnet link_rollup_5m table via the DoubleZero MCP to confirm row shapes and that the impaired links called out in the issue light up.
5. make go-test and make go-lint to confirm no regressions.

Estimated Scope

Production code (excluding tests and docs):

File	New lines (approx)
internal/worker/criteria.go (modify)	+35
internal/worker/clickhouse.go (modify)	+60
internal/worker/link_health.go (new)	+110
cmd/device-health-oracle/main.go (modify)	+20
Total	~225

Well within the 500-line threshold — single PR is appropriate. Tests will add ~250-300 more lines but those are excluded from the budget.

Open Questions

1. Should the recovery window be a separate flag (--link-recovery-slot-count) rather than reusing DrainedSlotCount? The issue says reuse DrainedSlotCount, so I'll go with that, but flagging in case the reviewer prefers explicit naming.
2. Should we also exclude buckets where status != 'activated'? The link_rollup_5m has a status field. If a link is hard-drained, its rollup will likely show isis_down = true, but we already only evaluate links where the worker iterates them — LinkStatus filtering happens implicitly because the activator manages who's in the iteration. Probably no extra filter needed, but worth confirming during code review.
3. Logging on transition. Currently the evaluator logs "Link criterion not met" on failure. For demotions specifically (RFS → Impaired), we may want a louder log at WARN level since that's a state change with operational implications. Will include this in the implementation as a small add.

[nikw9944]

Work Log — waiting_review

Now I'll overwrite with the revised plan that resolves the three operator decisions.

STATUS: COMPLETE — Revised plan saved to docs/work-plan-2652.md.

Work Plan — Issue #2652: device-health-oracle link impairment detection

Summary

The device-health-oracle (DHO) currently has zero LinkCriterions configured, so links auto-advance from Pending to ReadyForService and stay there forever — there is no demotion path. The issue is to detect impaired links (ISIS down or excessive packet loss) from the existing link_rollup_5m ClickHouse table and write LinkHealth = Impaired onchain, plus a slower "recovery" path that promotes back to ReadyForService when the link is consistently clean over the recovery window. This is a reporting signal only — the serviceability program does not (yet) gate link.status transitions on LinkHealth.

Approach

Bidirectional LinkHealthEvaluator

Today LinkHealthEvaluator.Evaluate is one-directional: any non-ReadyForService link is checked against the criteria, and ReadyForService is treated as terminal. We extend it to three branches that mirror how DeviceHealthEvaluator advances stages, but with a demote path:

Current health	Action
Unknown / Pending	Run ReadyForServiceCriteria. All pass → promote to ReadyForService.
ReadyForService	Run ImpairmentCriteria (point-in-time check). Any fail → demote to Impaired.
Impaired	Run ImpairmentCriteria over recovery window. All pass → promote to ReadyForService.

Both branches use the same LinkCriterion interface, but with different windows:

• Impairment check (RFS → Impaired): "is the most recent bucket bad?" — fast, single-bucket
• Recovery check (Impaired → RFS): "has every bucket in the last N minutes been clean?" — slow, full window

The simplest way to express that is to give LinkCriterion.Check access to a window via the context (parallel to DeviceBurnIn), and have the criterion query different aggregations depending on whether it's in "single bucket" vs "all buckets" mode. We pass the mode through context similarly to BurnInTimes.

LinkBurnIn helper

Add a helper parallel to DeviceBurnIn that resolves the recovery window from DrainedSlotCount (already plumbed through the worker). Naming the helper LinkBurnIn keeps the analogy to devices, but the meaning is "link recovery window". The helper extracts the DrainedStart time from the existing BurnInTimes (no new ledger calls needed) and returns (start, now, expectedMinutes, ok).

LinkHealthCriterion (single criterion, two modes)

A single criterion type, LinkHealthCriterion, with an internal mode:

• ModeImpairment: query the most recent link_rollup_5m bucket for the link. If isis_down is true OR a_loss_pct > threshold OR z_loss_pct > threshold → fail. (Failure here means "the link is impaired" — the evaluator translates failure into a demote.)
• ModeRecovery: query all link_rollup_5m buckets in [start, now]. If any bucket has isis_down = true or a_loss_pct > threshold or z_loss_pct > threshold → fail. (Failure means "the link has not been clean for the full window" — the evaluator keeps the link at Impaired.)

The evaluator wires up two instances of the same criterion, one in each slot, both pointing at the same ClickHouse checker.

LinkHealthChecker interface

Two query methods on the ClickHouse client:

type LinkHealthChecker interface {
    LinkHealthRecent(ctx context.Context, linkPubkey string) (isisDown bool, aLossPct, zLossPct float64, found bool, err error)
    LinkHealthWindowAllClean(ctx context.Context, linkPubkey string, start, end time.Time, lossThreshold float64) (allClean bool, err error)
}

LinkHealthRecent returns the latest bucket's health fields. LinkHealthWindowAllClean returns true if every bucket in the window is clean (isis_down = false AND a_loss_pct <= threshold AND z_loss_pct <= threshold). Pushing the threshold into the query keeps the result a single bool and avoids streaming rows.

The link_rollup_5m table also has a provisioning flag — buckets where provisioning = true should be excluded from both queries to avoid flagging links that are still being brought up. We do not filter on status: the operator has verified that hard-drained links surface as isis_down = true in link_rollup_5m, so the existing impairment signal already covers that case without an explicit filter.

Wiring in main.go

Add a --link-loss-threshold flag (default 5.0). When ClickHouse is enabled, instantiate two LinkHealthCriterions (impairment + recovery modes) and pass them to the evaluator on the new ImpairmentCriteria field. The recovery window reuses the existing DrainedSlotCount flag — no new flag introduced.

Edge cases handled in the evaluator

• No data for a link: LinkHealthRecent returns found = false. We treat "no data" as "do not demote" — better than flapping every link in a brand-new environment. A link with no telemetry stays at its current health.
• Recovery window too short: When expectedMinutes == 0 (newly created environment), we can't recover yet — keep at Impaired. (Inverse of the device-side "zero burn-in passes" rule, because here the window is a recovery dwell not a burn-in.)
• Currently-provisioning link: skipped in the SQL via provisioning = false.

Files to Change

Modify

• controlplane/device-health-oracle/internal/worker/criteria.go

  • Add LinkBurnIn(ctx) (start, now, expectedMinutes, ok) helper that pulls DrainedStart/Now out of the existing BurnInTimes.
  • Add ImpairmentCriteria []LinkCriterion field to LinkHealthEvaluator.
  • Rewrite LinkHealthEvaluator.Evaluate to handle three branches (Pending/Unknown, ReadyForService, Impaired) with bidirectional transitions.
  • Refactor the criterion-loop to a checkAllLink helper (parallel to checkAll) since it's now used in two places.
  • Demotion (RFS → Impaired) and recovery (Impaired → RFS) log lines stay at the same level as existing link-criterion logging — no WARN escalation.

• controlplane/device-health-oracle/internal/worker/criteria_test.go

  • Add tests covering: ReadyForService with impairment criterion fail → Impaired; ReadyForService with all impairment criteria pass → stays RFS; Impaired with all recovery criteria pass → RFS; Impaired with recovery fail → stays Impaired; Pending behavior unchanged.

• controlplane/device-health-oracle/internal/worker/clickhouse.go

  • Add LinkHealthChecker interface with LinkHealthRecent and LinkHealthWindowAllClean.
  • Implement both methods on ClickHouseClient against the link_rollup_5m table. Exclude provisioning = true buckets.

• controlplane/device-health-oracle/internal/worker/clickhouse_test.go

  • Add tests for the new query methods (mock-based, like existing tests).

• controlplane/device-health-oracle/cmd/device-health-oracle/main.go

  • Add --link-loss-threshold flag (default 5.0).
  • When ClickHouse is wired up, instantiate the two-mode LinkHealthCriterions and pass them to the evaluator's ImpairmentCriteria.

Create

• controlplane/device-health-oracle/internal/worker/link_health.go

  • LinkHealthCriterion struct with mode (impairment vs recovery), checker LinkHealthChecker, lossThreshold float64, log *slog.Logger.
  • Name() returns "link_health_impairment" or "link_health_recovery" based on mode.
  • Check(ctx, link) dispatches to the appropriate query. Treats "no data" as pass for impairment mode, fail for recovery mode (so a link without data can't recover, but also can't be demoted — keeps existing health).

• controlplane/device-health-oracle/internal/worker/link_health_test.go

  • Unit tests for both modes, both query paths, "no data" behavior, and threshold edge cases.

Doc updates

• CHANGELOG.md — entry under Unreleased / DeviceHealthOracle section: "Detect impaired links from link_rollup_5m (ISIS down or packet loss > threshold) and write LinkHealth = Impaired. Recover to ReadyForService after a clean recovery window. Bidirectional transitions, configurable via --link-loss-threshold."
• No README/CLAUDE.md updates needed — neither documents this component's evaluation logic, and the new --link-loss-threshold flag is discoverable via --help.

Risks & Considerations

1. Flapping on borderline links. The asymmetric design (single bucket triggers impairment, full window required to recover) is the explicit mitigation. Worth confirming on mainnet data after rollout that the default 5% threshold doesn't bounce too often.
2. link_rollup_5m lag. The most recent bucket is not always complete. Querying bucket_ts <= now - 5min would skip the in-flight bucket, but the issue says "most recent bucket" — we'll take the latest closed bucket via ORDER BY bucket_ts DESC LIMIT 1. If the table has buckets aligned to fixed 5-min boundaries with the current bucket included pre-finalization, this is fine: the latest complete bucket will be chosen on the next tick once a fuller bucket exists.
3. Recovery window length. Reusing DrainedSlotCount (~30 min) means a link must be clean for 30 min to recover. That's six 5-min buckets. Long enough to absorb routine flaps, short enough to recover within an oncall response cycle.
4. No data ⇒ no transition. If link_rollup_5m has zero rows for a link (telemetry gap, new link), we don't demote. We also don't recover. This is the safe default, but if telemetry pipelines silently break, impaired links will be stuck in Impaired forever. Acceptable — visible in dashboards as "no rollup data".
5. LinkHealth doesn't gate link.status. The serviceability program's check_status_transition() is intentionally not yet checking LinkHealth. We're producing a signal, not enforcing a gate. The CHANGELOG entry should make that explicit so reviewers don't expect operational changes from this PR alone.
6. --link-loss-threshold default = 5%. This is what the issue specifies. Easy to tune via flag.
7. Backwards compatibility. Existing deployments without ClickHouse will continue to behave as before — links auto-advance, no impairment detection, no demotion. The new criteria only attach when ClickHouse is wired up.

Testing Strategy

1. Unit tests for LinkHealthEvaluator covering all six transition cases (3 starting states × pass/fail).
2. Unit tests for LinkHealthCriterion covering both modes, "no data" handling, threshold boundaries, and ClickHouse error propagation.
3. Unit tests for ClickHouseClient.LinkHealthRecent / LinkHealthWindowAllClean using the existing mock-conn pattern, validating SQL shape (table name quoting, provisioning = false filter, threshold parameter binding).
4. Manual SQL validation — before merging, run the recovery and impairment queries against the mainnet link_rollup_5m table via the DoubleZero MCP to confirm row shapes and that the impaired links called out in the issue light up.
5. make go-test and make go-lint to confirm no regressions.

Estimated Scope

Production code (excluding tests and docs):

File	New lines (approx)
internal/worker/criteria.go (modify)	+35
internal/worker/clickhouse.go (modify)	+60
internal/worker/link_health.go (new)	+110
cmd/device-health-oracle/main.go (modify)	+20
Total	~225

Well within the 500-line threshold — single PR is appropriate. Tests will add ~250-300 more lines but those are excluded from the budget.

Operator Decisions Locked In (revision 1)

These were open in revision 0 and have been resolved by the operator:

1. Recovery window flag — reuse DrainedSlotCount. No separate --link-recovery-slot-count flag introduced.
2. Hard-drained link filter — not needed. Operator verified that hard-drained links already surface as isis_down = true in link_rollup_5m, so the existing impairment criterion catches them without an explicit status filter.
3. Demotion log level — stays at the same level as existing link-criterion logs. RFS → Impaired is a frequent operational event without direct user impact, so a WARN-level signal would be noise.

--- Result: success | Session cost: $0.6982 | Turns: 6 | Tokens: 11 in / 15120 out | 2026-05-05 22:07:40 UTC ---

[nikw9944]

Approved Work Plan (Revision 1)

Approved Work Plan (Revision 1)

Work Plan — Issue #2652: device-health-oracle link impairment detection

Summary

The device-health-oracle (DHO) currently has zero LinkCriterions configured, so links auto-advance from Pending to ReadyForService and stay there forever — there is no demotion path. The issue is to detect impaired links (ISIS down or excessive packet loss) from the existing link_rollup_5m ClickHouse table and write LinkHealth = Impaired onchain, plus a slower "recovery" path that promotes back to ReadyForService when the link is consistently clean over the recovery window. This is a reporting signal only — the serviceability program does not (yet) gate link.status transitions on LinkHealth.

Approach

Bidirectional LinkHealthEvaluator

Today LinkHealthEvaluator.Evaluate is one-directional: any non-ReadyForService link is checked against the criteria, and ReadyForService is treated as terminal. We extend it to three branches that mirror how DeviceHealthEvaluator advances stages, but with a demote path:

Current health	Action
Unknown / Pending	Run ReadyForServiceCriteria. All pass → promote to ReadyForService.
ReadyForService	Run ImpairmentCriteria (point-in-time check). Any fail → demote to Impaired.
Impaired	Run ImpairmentCriteria over recovery window. All pass → promote to ReadyForService.

Both branches use the same LinkCriterion interface, but with different windows:

• Impairment check (RFS → Impaired): "is the most recent bucket bad?" — fast, single-bucket
• Recovery check (Impaired → RFS): "has every bucket in the last N minutes been clean?" — slow, full window

The simplest way to express that is to give LinkCriterion.Check access to a window via the context (parallel to DeviceBurnIn), and have the criterion query different aggregations depending on whether it's in "single bucket" vs "all buckets" mode. We pass the mode through context similarly to BurnInTimes.

LinkBurnIn helper

Add a helper parallel to DeviceBurnIn that resolves the recovery window from DrainedSlotCount (already plumbed through the worker). Naming the helper LinkBurnIn keeps the analogy to devices, but the meaning is "link recovery window". The helper extracts the DrainedStart time from the existing BurnInTimes (no new ledger calls needed) and returns (start, now, expectedMinutes, ok).

LinkHealthCriterion (single criterion, two modes)

A single criterion type, LinkHealthCriterion, with an internal mode:

• ModeImpairment: query the most recent link_rollup_5m bucket for the link. If isis_down is true OR a_loss_pct > threshold OR z_loss_pct > threshold → fail. (Failure here means "the link is impaired" — the evaluator translates failure into a demote.)
• ModeRecovery: query all link_rollup_5m buckets in [start, now]. If any bucket has isis_down = true or a_loss_pct > threshold or z_loss_pct > threshold → fail. (Failure means "the link has not been clean for the full window" — the evaluator keeps the link at Impaired.)

The evaluator wires up two instances of the same criterion, one in each slot, both pointing at the same ClickHouse checker.

LinkHealthChecker interface

Two query methods on the ClickHouse client:

type LinkHealthChecker interface {
    LinkHealthRecent(ctx context.Context, linkPubkey string) (isisDown bool, aLossPct, zLossPct float64, found bool, err error)
    LinkHealthWindowAllClean(ctx context.Context, linkPubkey string, start, end time.Time, lossThreshold float64) (allClean bool, err error)
}

LinkHealthRecent returns the latest bucket's health fields. LinkHealthWindowAllClean returns true if every bucket in the window is clean (isis_down = false AND a_loss_pct <= threshold AND z_loss_pct <= threshold). Pushing the threshold into the query keeps the result a single bool and avoids streaming rows.

The link_rollup_5m table also has a provisioning flag — buckets where provisioning = true should be excluded from both queries to avoid flagging links that are still being brought up. We do not filter on status: the operator has verified that hard-drained links surface as isis_down = true in link_rollup_5m, so the existing impairment signal already covers that case without an explicit filter.

Wiring in main.go

Add a --link-loss-threshold flag (default 5.0). When ClickHouse is enabled, instantiate two LinkHealthCriterions (impairment + recovery modes) and pass them to the evaluator on the new ImpairmentCriteria field. The recovery window reuses the existing DrainedSlotCount flag — no new flag introduced.

Edge cases handled in the evaluator

• No data for a link: LinkHealthRecent returns found = false. We treat "no data" as "do not demote" — better than flapping every link in a brand-new environment. A link with no telemetry stays at its current health.
• Recovery window too short: When expectedMinutes == 0 (newly created environment), we can't recover yet — keep at Impaired. (Inverse of the device-side "zero burn-in passes" rule, because here the window is a recovery dwell not a burn-in.)
• Currently-provisioning link: skipped in the SQL via provisioning = false.

Files to Change

Modify

• controlplane/device-health-oracle/internal/worker/criteria.go

  • Add LinkBurnIn(ctx) (start, now, expectedMinutes, ok) helper that pulls DrainedStart/Now out of the existing BurnInTimes.
  • Add ImpairmentCriteria []LinkCriterion field to LinkHealthEvaluator.
  • Rewrite LinkHealthEvaluator.Evaluate to handle three branches (Pending/Unknown, ReadyForService, Impaired) with bidirectional transitions.
  • Refactor the criterion-loop to a checkAllLink helper (parallel to checkAll) since it's now used in two places.
  • Demotion (RFS → Impaired) and recovery (Impaired → RFS) log lines stay at the same level as existing link-criterion logging — no WARN escalation.

• controlplane/device-health-oracle/internal/worker/criteria_test.go

  • Add tests covering: ReadyForService with impairment criterion fail → Impaired; ReadyForService with all impairment criteria pass → stays RFS; Impaired with all recovery criteria pass → RFS; Impaired with recovery fail → stays Impaired; Pending behavior unchanged.

• controlplane/device-health-oracle/internal/worker/clickhouse.go

  • Add LinkHealthChecker interface with LinkHealthRecent and LinkHealthWindowAllClean.
  • Implement both methods on ClickHouseClient against the link_rollup_5m table. Exclude provisioning = true buckets.

• controlplane/device-health-oracle/internal/worker/clickhouse_test.go

  • Add tests for the new query methods (mock-based, like existing tests).

• controlplane/device-health-oracle/cmd/device-health-oracle/main.go

  • Add --link-loss-threshold flag (default 5.0).
  • When ClickHouse is wired up, instantiate the two-mode LinkHealthCriterions and pass them to the evaluator's ImpairmentCriteria.

Create

• controlplane/device-health-oracle/internal/worker/link_health.go

  • LinkHealthCriterion struct with mode (impairment vs recovery), checker LinkHealthChecker, lossThreshold float64, log *slog.Logger.
  • Name() returns "link_health_impairment" or "link_health_recovery" based on mode.
  • Check(ctx, link) dispatches to the appropriate query. Treats "no data" as pass for impairment mode, fail for recovery mode (so a link without data can't recover, but also can't be demoted — keeps existing health).

• controlplane/device-health-oracle/internal/worker/link_health_test.go

  • Unit tests for both modes, both query paths, "no data" behavior, and threshold edge cases.

Doc updates

• CHANGELOG.md — entry under Unreleased / DeviceHealthOracle section: "Detect impaired links from link_rollup_5m (ISIS down or packet loss > threshold) and write LinkHealth = Impaired. Recover to ReadyForService after a clean recovery window. Bidirectional transitions, configurable via --link-loss-threshold."
• No README/CLAUDE.md updates needed — neither documents this component's evaluation logic, and the new --link-loss-threshold flag is discoverable via --help.

Risks & Considerations

1. Flapping on borderline links. The asymmetric design (single bucket triggers impairment, full window required to recover) is the explicit mitigation. Worth confirming on mainnet data after rollout that the default 5% threshold doesn't bounce too often.
2. link_rollup_5m lag. The most recent bucket is not always complete. Querying bucket_ts <= now - 5min would skip the in-flight bucket, but the issue says "most recent bucket" — we'll take the latest closed bucket via ORDER BY bucket_ts DESC LIMIT 1. If the table has buckets aligned to fixed 5-min boundaries with the current bucket included pre-finalization, this is fine: the latest complete bucket will be chosen on the next tick once a fuller bucket exists.
3. Recovery window length. Reusing DrainedSlotCount (~30 min) means a link must be clean for 30 min to recover. That's six 5-min buckets. Long enough to absorb routine flaps, short enough to recover within an oncall response cycle.
4. No data ⇒ no transition. If link_rollup_5m has zero rows for a link (telemetry gap, new link), we don't demote. We also don't recover. This is the safe default, but if telemetry pipelines silently break, impaired links will be stuck in Impaired forever. Acceptable — visible in dashboards as "no rollup data".
5. LinkHealth doesn't gate link.status. The serviceability program's check_status_transition() is intentionally not yet checking LinkHealth. We're producing a signal, not enforcing a gate. The CHANGELOG entry should make that explicit so reviewers don't expect operational changes from this PR alone.
6. --link-loss-threshold default = 5%. This is what the issue specifies. Easy to tune via flag.
7. Backwards compatibility. Existing deployments without ClickHouse will continue to behave as before — links auto-advance, no impairment detection, no demotion. The new criteria only attach when ClickHouse is wired up.

Testing Strategy

1. Unit tests for LinkHealthEvaluator covering all six transition cases (3 starting states × pass/fail).
2. Unit tests for LinkHealthCriterion covering both modes, "no data" handling, threshold boundaries, and ClickHouse error propagation.
3. Unit tests for ClickHouseClient.LinkHealthRecent / LinkHealthWindowAllClean using the existing mock-conn pattern, validating SQL shape (table name quoting, provisioning = false filter, threshold parameter binding).
4. Manual SQL validation — before merging, run the recovery and impairment queries against the mainnet link_rollup_5m table via the DoubleZero MCP to confirm row shapes and that the impaired links called out in the issue light up.
5. make go-test and make go-lint to confirm no regressions.

Estimated Scope

Production code (excluding tests and docs):

File	New lines (approx)
internal/worker/criteria.go (modify)	+35
internal/worker/clickhouse.go (modify)	+60
internal/worker/link_health.go (new)	+110
cmd/device-health-oracle/main.go (modify)	+20
Total	~225

Well within the 500-line threshold — single PR is appropriate. Tests will add ~250-300 more lines but those are excluded from the budget.

Operator Decisions Locked In (revision 1)

These were open in revision 0 and have been resolved by the operator:

1. Recovery window flag — reuse DrainedSlotCount. No separate --link-recovery-slot-count flag introduced.
2. Hard-drained link filter — not needed. Operator verified that hard-drained links already surface as isis_down = true in link_rollup_5m, so the existing impairment criterion catches them without an explicit status filter.
3. Demotion log level — stays at the same level as existing link-criterion logs. RFS → Impaired is a frequent operational event without direct user impact, so a WARN-level signal would be noise.

[nikw9944]

Work Log — waiting_review

Confirmed schema. Note there can be multiple rows per (bucket_ts, link_pk) so I'll use ORDER BY bucket_ts DESC, ingested_at DESC LIMIT 1 for the recent query.

Now let me implement the changes. Start with criteria.go - adding LinkBurnIn helper and bidirectional evaluator.

Now update the LinkHealthEvaluator for bidirectional transitions:

Looking more carefully at the design, I need two separate fields on the evaluator (one for impairment check, one for recovery check) since they use different windows. Let me refine:

Now add the LinkHealthChecker interface and queries to clickhouse.go:

Now I need to add the database/sql and errors imports:

Now create link_health.go:

Now wire up in main.go:

Let me build to make sure the production code compiles before writing tests:

Build succeeded. Now write the tests:

Add the link-health evaluator tests:

Now write tests for the LinkHealthCriterion and the new ClickHouse queries:

Now add ClickHouse-level tests:

Run the tests:

Tests pass. Run lint:

Update CHANGELOG.md:

Let me run a broader check to ensure I haven't broken anything else and check for golangci-lint:

All tests pass. Now let me get the diff for review:

Now I need to run reviews before pushing. Let me first commit so the work is captured, then run reviews against origin/main...HEAD.

[nikw9944]

Architecture review findings:

• Critical: 0
• High: 2
• Medium: 5
• Low: 6

Architecture Review

Critical

• None

High

• Correctness/SQL semantics: LinkHealthWindowAllClean counts rows, not distinct buckets. The link_rollup_5m table has multiple rows per (link_pk, bucket_ts) differing by ingested_at (verified in mainnet: 3,965 duplicate buckets in the last 7 days, often 2–3 rows per bucket). The query's total_buckets = count() and bad_buckets = countIf(...) therefore inflate. In practice today the duplicates carry identical health values so bad == 0 happens to be correct, but this is implicit reliance on rollup-pipeline idempotency that is not documented anywhere — if the writer ever produces a corrected late row (e.g., isis_down=true first, then isis_down=false), this query will keep the link Impaired even though every distinct bucket is clean.

  • Location: controlplane/device-health-oracle/internal/worker/clickhouse.go:158-180
  • Recommendation: Use argMax(...) to dedupe to the latest ingested_at per bucket (mirroring the comment on LinkHealthRecent). E.g. wrap in a subquery: SELECT bucket_ts, argMax(isis_down, ingested_at) AS isis_down, argMax(a_loss_pct, ingested_at), argMax(z_loss_pct, ingested_at) FROM ... GROUP BY bucket_ts and apply the bad-row predicate in an outer aggregate. At minimum, document the assumption with a code comment + a unit test that asserts the SQL does the dedupe.

• Stale-data risk for LinkHealthRecent: The query has no recency filter. If a link's telemetry pipeline silently breaks while the last bucket happened to have isis_down=true, that bucket can stay "the most recent" indefinitely and continuously demote/keep the link impaired. Conversely if the last bucket was clean, the impairment check will pass forever even though no fresh data exists. The work plan's "no data ⇒ no transition" rule only applies to the literal "zero rows" case; "stale rows" silently masquerade as fresh data.

  • Location: controlplane/device-health-oracle/internal/worker/clickhouse.go:95-119
  • Recommendation: Add a bucket_ts >= now() - INTERVAL N MINUTE floor (e.g., 15–30 min) and treat stale-only data as found=false. Document the chosen bound. Alternatively, return bucket_ts in the result and have the criterion enforce the recency check (keeps SQL simple, makes the threshold visible to operators via logs).

Medium

• Per-tick performance / N+1: Every link is queried individually each tick — at 166 active links today, that's 166 round-trips per tick (impairment query) plus extra queries for impaired-state links (recovery query). There's no concurrency, no IN (...) batching, and no skip for terminal-state links (LinkStatusDeleting, LinkStatusRejected, LinkStatusPending etc. are all evaluated). This won't bite today but scales linearly with link count and ClickHouse RTT.

  • Location: controlplane/device-health-oracle/internal/worker/worker.go:180-203 (loop) and link_health.go:60-67 (per-link query dispatch).
  • Recommendation (in order of effort/value):
    1. Skip evaluation entirely for links whose Status makes health updates meaningless (Deleting, Rejected, Pending, Provisioning, Requested).
    2. Replace per-link queries with two batch queries per tick: one returning the latest bucket per link (link_pk IN program-data set) and one returning bad-bucket-count per link over the recovery window. Cache by link_pk in the criterion via context. This makes the fan-in a constant 2 ClickHouse queries per tick regardless of link count.

• Missing criterion metric for links: DeviceHealthEvaluator.checkAll increments MetricCriterionResults{criterion, "pass"|"fail"} (criteria.go:121,124). The new LinkHealthEvaluator.checkAllLink does NOT emit this metric, so dashboards/alerts on the pass/fail counter will show device criteria but no link criteria — operators will not be able to graph impairment/recovery rates.

  • Location: controlplane/device-health-oracle/internal/worker/criteria.go:180-194
  • Recommendation: Increment MetricCriterionResults in checkAllLink symmetrically to checkAll (both pass and fail branches). Add a label distinguishing kind (device/link) if needed for safer dashboards.

• LinkHealthChecker.Close() not on the interface, but neither are the device-side analogs — and the wiring does defer chClient.Close() only: Minor design inconsistency. ControllerCallChecker has Close() error; the new LinkHealthChecker does not; InterfaceCountersChecker does not either. This is a pre-existing inconsistency the new interface inherits — worth a single cleanup.

  • Location: controlplane/device-health-oracle/internal/worker/clickhouse.go:18-22, 86-88, 111-125
  • Recommendation: Drop Close() from ControllerCallChecker (or add it consistently to the others). The *ClickHouseClient is what main.go calls Close() on directly via the concrete type — the interface method is unused.

• LinkHealthMode is exported but not idiomatic: Two-mode toggle implemented via an int enum + branching if c.mode == ... inside Check. The public surface here has LinkHealthModeImpairment and LinkHealthModeRecovery constants and a constructor that takes the mode as the first argument. Two distinct types (or two factory functions, e.g., NewLinkImpairmentCriterion / NewLinkRecoveryCriterion) would be cleaner: each one has a single, obvious Check body, eliminates the if mode == ... branches, makes invalid modes unrepresentable, and gives the criterion's Name() something to return without conditional logic. The shared internal struct can stay; only the constructor split changes.

  • Location: controlplane/device-health-oracle/internal/worker/link_health.go:13-67
  • Recommendation: Replace the mode flag with two thin constructors over a private base, or two separate LinkImpairmentCriterion / LinkRecoveryCriterion types implementing LinkCriterion. This also makes the asymmetric "no data" semantics easier to read because each type documents its own rule.

• Evaluator default case silently auto-promotes Pending links to RFS with no criteria: With ReadyForServiceCriteria: nil (the wiring in main.go), the default: arm of the new switch returns LinkHealthReadyForService immediately for Unknown/Pending links — same as before, but now the asymmetry is explicit: links auto-promote, and only ever demote via ClickHouse. If ClickHouse is offline at boot the link goes Pending → RFS instantly with no signal whatsoever. This is documented as backward-compatible behavior, but it's odd that the LinkHealthCriterion is wired into ImpairmentCriteria/RecoveryCriteria but not also ReadyForServiceCriteria — the same impairment check could gate the initial promotion (a link that's already isis_down shouldn't auto-promote).

  • Location: controlplane/device-health-oracle/cmd/device-health-oracle/main.go:172-177 and criteria.go:172-177
  • Recommendation: Either wire the impairment criterion into ReadyForServiceCriteria as well (so a Pending → RFS transition has the same gate as RFS → Impaired re-evaluation), or document explicitly why the initial promotion is unconditional. Today's behavior — a brand-new link with isis_down=true immediately reports RFS and only gets demoted on the next tick — is an avoidable visible blip.

Low

• LinkBurnIn naming/comment mismatch: The helper is named LinkBurnIn and lives in criteria.go paired with DeviceBurnIn, but its semantics (a recovery dwell, not a burn-in) are opposite: device-side expectedMinutes==0 means "pass", link-side expectedMinutes==0 means "fail". The criterion code carries an inline comment about this inversion. Naming the helper LinkRecoveryWindow(ctx) (start, now, length, ok) would make the intent self-evident and let you delete the inversion comment.

  • Location: controlplane/device-health-oracle/internal/worker/criteria.go:44-57, link_health.go:100-110
  • Recommendation: Rename to LinkRecoveryWindow (or similar) and drop the "burn-in" terminology for links.

• Recovery threshold log-line readability: The Debug log line at link_health.go:122-128 includes start, end, expectedMinutes, lossThreshold, but does NOT include the actual bad/total counts from the query — the underlying LinkHealthChecker discards them. Operators investigating "why is this link not recovering" have to write SQL by hand to see how many bad buckets there are.

  • Location: clickhouse.go:158-180, link_health.go:122-128
  • Recommendation: Have LinkHealthWindowAllClean return (bad, total uint64, found bool, err error) and log both numbers in the criterion. Cheap and dramatically improves debuggability.

• isis_down reason string lacks the bucket timestamp: The fail reason "isis adjacency down" (line 89) tells operators nothing about when. With the no-recency-filter issue above, a stale isis_down=true row from yesterday would just say "isis adjacency down" with no temporal anchor.

  • Location: controlplane/device-health-oracle/internal/worker/link_health.go:88-96
  • Recommendation: Have LinkHealthRecent also return the bucket timestamp and include it in both the debug log and the fail reason: "isis adjacency down (bucket=2026-05-06 16:25Z)".

• LinkHealthChecker interface is colocated with the concrete client: Other Checker interfaces in the same file follow the same pattern, so this is consistent — but it does mean the interface is in the worker package and any external test/mock has to import it. Not a blocker.

  • Location: controlplane/device-health-oracle/internal/worker/clickhouse.go:111-125
  • Recommendation: Optional — leave as-is for parity with ControllerCallChecker/InterfaceCountersChecker.

• Test gap: Pending → RFS path with criterion failure not asserted under new switch shape: TestLinkHealthEvaluator_CriterionFails_BlocksAdvancement covers Pending + failing ReadyForServiceCriteria, but there's no test for the cross-product "Pending link with ImpairmentCriteria set but ReadyForServiceCriteria empty" — i.e., does a fresh Pending link still skip impairment? Given that today's wiring leaves ReadyForServiceCriteria nil but populates ImpairmentCriteria, this path is exactly what runs in production.

  • Location: controlplane/device-health-oracle/internal/worker/criteria_test.go
  • Recommendation: Add a test asserting that with ImpairmentCriteria populated and ReadyForServiceCriteria=nil, a LinkHealthPending link advances directly to LinkHealthReadyForService without consulting impairment criteria.

• Test gap: ClickHouse query failure during Impaired → ReadyForService evaluation keeps link at Impaired (correct), but there's no end-to-end assertion of this through LinkHealthEvaluator — only at the criterion level. A small test wiring the real LinkHealthCriterion (with a failing checker) into LinkHealthEvaluator.RecoveryCriteria would lock the contract.

  • Location: controlplane/device-health-oracle/internal/worker/criteria_test.go, link_health_test.go
  • Recommendation: One additional table-driven test covering eval-level behavior on checker error.

• Hard-coded knowledge in two places: The default flag value 5.0 is in main.go, but the test in link_health_test.go also hard-codes 5.0. Not wrong, just a style nit — consider a worker.DefaultLinkLossThreshold const.

  • Location: cmd/device-health-oracle/main.go:47, internal/worker/link_health_test.go (multiple)
  • Recommendation: Optional.

Summary

The change is well-scoped and follows the existing criterion/evaluator patterns; tests are thorough at the unit level. The two material concerns are (1) the recovery SQL counts duplicate ingested rows rather than distinct buckets — currently masked by pipeline idempotency but a latent correctness bug — and (2) LinkHealthRecent has no recency floor, so stale telemetry can indefinitely demote or keep a link clean. Both are fixable with small SQL changes; everything else is operability/polish (link-criterion metric parity, batching for scale, mode-as-enum vs. distinct types, naming, debug log content).

[nikw9944]

Security review findings:

• Critical: 0
• High: 0
• Medium: 0
• Low: 3

Security Review

Critical

• None

High

• None

Medium

• None

Low

• Information disclosure (low risk): Error messages from ClickHouse are returned verbatim in criterion reason strings (e.g. fmt.Sprintf("clickhouse query failed: %v", err)) from link_health.go:74 and link_health.go:116. These reasons flow into the Info-level log line "Link criterion not met" in criteria.go and could leak ClickHouse internals (table schema hints, network endpoints, auth-failure details) to anyone with log read access. The DHO logs are operator-internal and the validDBName regex prevents the database name itself from being attacker-influenced, so impact is bounded.

  • Location: controlplane/device-health-oracle/internal/worker/link_health.go:74,116
  • Recommendation: Consider logging the full error at error-level (already done) but returning a generic reason (e.g. "clickhouse query failed") without %v interpolation, to keep transient backend errors out of the criterion-trace path that may be aggregated/exported elsewhere.

• Input validation (defensive): --link-loss-threshold is a flag.Float64 with no bounds check. Negative, NaN, or Inf values silently change behaviour: a negative threshold marks every bucket impaired (mass flap of all links to Impaired onchain — onchain write storm); NaN makes every comparison false (impairment never triggers); +Inf prevents any impairment detection. The flag is operator-set, so this is a misconfiguration risk rather than an attacker-facing input, but the DHO holds a Solana signer keypair and writes onchain transactions, so a misconfig that triggers a write-amplification storm has real cost.

  • Location: controlplane/device-health-oracle/cmd/device-health-oracle/main.go:47
  • Recommendation: Validate *linkLossThreshold is finite and within [0, 100] at startup; fail fast on out-of-range values.

• Resource exhaustion (theoretical): LinkHealthWindowAllClean issues one query per Impaired link per tick over a window of up to DrainedSlotCount slots (~30 min default). The query uses countIf so the result row size is bounded, but the scanned partition range scales with the window size. DrainedSlotCount is operator-controlled and the per-link query is O(buckets) against link_rollup_5m (5-minute rollups), so the worst case is small. There is no per-tick concurrency bound visible here for many simultaneously Impaired links, but this is not attacker-influenceable since the link set is constrained to onchain-registered links that the activator approved.

  • Location: controlplane/device-health-oracle/internal/worker/clickhouse.go:158-180
  • Recommendation: None required in this PR. If the link count grows, consider a single batched query keyed by link list rather than N queries per tick.

Summary

The change is well-scoped and the SQL injection surface is correctly handled: the only Sprintf-interpolated value is c.db, which is gated by the ^[a-zA-Z0-9_-]+$ regex at construction (clickhouse.go:16,31) and additionally wrapped in double quotes; all other inputs (linkPubkey, threshold, time bounds) flow through ? bind parameters. The linkPubkey itself is derived from [32]byte onchain data via solana.PublicKeyFromBytes(...).String(), so it is structurally constrained to base58 regardless of upstream tampering. No new authentication or auth surface is introduced. Findings are limited to defensive hardening: validating the new float flag and avoiding raw error interpolation into criterion reason strings.