package main

import (
	"bufio"
	"encoding/json"
	"fmt"
	"os"
	"slices"
)

// trajectorySummary is the harness-side digest of one run's trajectory file:
// where the wall clock went, split between tool execution and everything the
// model spent between calls (thinking, streaming, provider latency).
type trajectorySummary struct {
	Path    string `json:"path"`
	Records int    `json:"records"`
	SpanMs  int64  `json:"span_ms"`
	ToolMs  int64  `json:"tool_ms"`
	ModelMs int64  `json:"model_ms"` // SpanMs − tool wall clock, floored at zero
	// Round decomposition: a round's gap runs from the turn start (or the
	// batch's last tool_result) to the next top-level tool_dispatch; the
	// final segment to the last record is the answer round.
	ModelRounds     int   `json:"model_rounds"`
	ModelGapTotalMs int64 `json:"model_gap_total_ms"`
	ModelGapP95Ms   int64 `json:"model_gap_p95_ms"`
	Retries         int   `json:"retries,omitempty"`
	Compactions     int   `json:"compactions,omitempty"`

	// Batch decomposition: one batch is one round's top-level tool calls.
	// ToolWallMs is the union of execution intervals (parallel calls counted
	// once) plus durations of calls that carried no timestamps.
	ToolWallMs       int64 `json:"tool_wall_ms,omitempty"`
	ToolBatches      int   `json:"tool_batches,omitempty"`
	TopLevelCalls    int   `json:"top_level_calls,omitempty"`
	MaxBatchSize     int   `json:"max_batch_size,omitempty"`
	ParallelBatches  int   `json:"parallel_batches,omitempty"`   // ≥2 calls actually overlapped
	ParallelSavedMs  int64 `json:"parallel_saved_ms,omitempty"`  // Σ durations − batch wall
	SingleReadRounds int   `json:"single_read_rounds,omitempty"` // 1-call read-only batches
	SingleReadStreak int   `json:"single_read_streak,omitempty"` // longest consecutive run
	StartDelayP95Ms  int64 `json:"start_delay_p95_ms,omitempty"` // dispatch→start, in-batch queue

	// Recovery decomposition: a round whose gap contained a provider retry,
	// missing-reasoning replay, or empty-final retry is a recovery round; clean
	// p95 excludes them so adapter flakiness reads as adapter cost, not agent.
	StreamRetries     int   `json:"stream_retries,omitempty"`
	HeaderRetries     int   `json:"header_retries,omitempty"`
	ReasoningReplays  int   `json:"reasoning_replays,omitempty"` // extra exact-replay requests
	EmptyFinalRetries int   `json:"empty_final_retries,omitempty"`
	RecoveryRounds    int   `json:"recovery_rounds,omitempty"`
	RecoveryGapMs     int64 `json:"recovery_gap_ms,omitempty"`
	CleanGapP95Ms     int64 `json:"clean_gap_p95_ms,omitempty"`

	// Wall decomposition: disjoint buckets partitioning the span, allocated by
	// priority (tools > retry backoff > compaction > model streaming with the
	// planner split out > agent overhead), so overlaps are never double-booked.
	RetryWaitMs     int64 `json:"retry_wait_ms,omitempty"`     // retrying → next attempt begin
	CompactionMs    int64 `json:"compaction_ms,omitempty"`     // compaction_started → done
	PlannerStreamMs int64 `json:"planner_stream_ms,omitempty"` // attempts closed by planner usage
	ModelStreamMs   int64 `json:"model_stream_ms,omitempty"`   // remaining sampling attempts
	AgentOtherMs    int64 `json:"agent_other_ms,omitempty"`    // span remainder: assembly, guards, idle

	// Phase-trace inputs: content-free firsts and counts for the per-task trace.
	TTFTMs           int64 `json:"ttft_ms,omitempty"`       // span start → first output delta
	FirstToolMs      int64 `json:"first_tool_ms,omitempty"` // span start → first tool start
	PlannerRequests  int   `json:"planner_requests,omitempty"`
	ExecutorRequests int   `json:"executor_requests,omitempty"`
	SubagentRequests int   `json:"subagent_requests,omitempty"`
	// RequestsBySource keeps every origin honest — goal-evaluator, compaction
	// and capability-router calls must not masquerade as executor rounds.
	RequestsBySource  map[string]int `json:"requests_by_source,omitempty"`
	ToolQueueMs       int64          `json:"tool_queue_ms,omitempty"`       // Σ dispatch→start delays
	NoProgressSignals int            `json:"no_progress_signals,omitempty"` // progress_guard escalations

	// Round outcomes: each classified round's gap booked to what it produced.
	// Productive = evidence_gain/mutation/verification/finalization; the rest
	// accumulates into WastedGapMs — the knife-target readout.
	RoundOutcomes  map[string]int   `json:"round_outcomes,omitempty"`
	RoundOutcomeMs map[string]int64 `json:"round_outcome_ms,omitempty"`
	UsefulRounds   int              `json:"useful_rounds,omitempty"`
	WastedGapMs    int64            `json:"wasted_gap_ms,omitempty"`

	// Mechanism ledger inputs: recovery gap split per taint kind, and the
	// executor-handoff nudge count (a correctness mechanism that buys a whole
	// extra model round each time it fires).
	HandoffNudges       int              `json:"handoff_nudges,omitempty"`
	RecoveryGapMsByKind map[string]int64 `json:"recovery_gap_ms_by_kind,omitempty"`

	// Tool surface: the schema tax every top-level request re-pays, and the
	// surface churn (connect_tool_source calls, provider prefix resets) that
	// trades that tax against mid-session cache invalidation.
	SchemaTokensMax   int64 `json:"schema_tokens_max,omitempty"`   // largest per-request schema footprint
	SchemaTokensTotal int64 `json:"schema_tokens_total,omitempty"` // Σ schema tokens across requests
	PromptTokensSeen  int64 `json:"prompt_tokens_seen,omitempty"`  // Σ prompt tokens (schema share denominator)
	PrefixResets      int   `json:"prefix_resets,omitempty"`       // usage events with prefixChanged
	ConnectCalls      int   `json:"connect_calls,omitempty"`       // connect_tool_source dispatches

	// Cold/warm evidence: the first top-level request's cache split. A cold
	// session pays the whole prefix as miss; a warmed one starts near-hit.
	FirstReqCacheHitTokens  int64 `json:"first_req_cache_hit_tokens,omitempty"`
	FirstReqCacheMissTokens int64 `json:"first_req_cache_miss_tokens,omitempty"`

	// Shadow contract audit (last of the turn): what the observing contract
	// concluded, priced against the hidden grader by the report.
	ShadowIntent   string `json:"shadow_intent,omitempty"`
	ShadowVerdict  string `json:"shadow_verdict,omitempty"`
	ShadowComplete bool   `json:"shadow_complete,omitempty"`

	// Completion report (last of the turn): the host-authored receipt's
	// verdict and the gaps it refused to hide, priced against the grader.
	CompletionVerdict  string   `json:"completion_verdict,omitempty"`
	CompletionGaps     int      `json:"completion_gaps,omitempty"`
	CompletionGapKinds []string `json:"completion_gap_kinds,omitempty"`
	ClaimsVerified     int      `json:"claims_verified,omitempty"`
	ClaimsUnbacked     int      `json:"claims_unbacked,omitempty"`

	// Outcome shadow: the runtime outcome scorer's per-round series condensed,
	// or a verification-receipt backfill for recordings that predate it.
	Outcome *outcomeSummary `json:"outcome,omitempty"`

	// Anchor-safety shadow: content-free interval-fingerprint decisions. The
	// trajectory never contains paths, anchors, source text, or line hashes.
	AnchorSafety *anchorSafetySummary `json:"anchor_safety,omitempty"`

	// Cognition: executor reasoning/completion joined per model round, plus a
	// census of slow rounds — gaps that bought unusually large thinking.
	ReasoningTokensTotal     int64         `json:"reasoning_tokens_total,omitempty"`
	CompletionTokensTotal    int64         `json:"completion_tokens_total,omitempty"`
	SlowRounds               int           `json:"slow_rounds,omitempty"`
	SlowRoundGapMs           int64         `json:"slow_round_gap_ms,omitempty"`
	SlowRoundReasoningTokens int64         `json:"slow_round_reasoning_tokens,omitempty"`
	Rounds                   []roundDigest `json:"rounds,omitempty"`

	// Delegation admission shadow: verdicts recorded by the runtime, and the
	// subagent time spent by tools the shadow would have denied.
	DelegationCalls    int   `json:"delegation_calls,omitempty"`
	DelegationDenies   int   `json:"delegation_denies,omitempty"`
	DeniedDelegationMs int64 `json:"denied_delegation_ms,omitempty"`
}

// toolWall is the best available tool wall-clock: interval union when the
// recording carried timestamps, else the duration sum (older trajectories).
func (s *trajectorySummary) toolWall() int64 {
	if s.ToolWallMs > 0 {
		return s.ToolWallMs
	}
	return s.ToolMs
}

// roundCall is one call's outcome-relevant facts for round classification.
type roundCall struct {
	name, verification string
	readOnly, errored  bool
	resolved, dup      bool
}

// gapInfo carries one model gap until its batch closes and can classify it.
// The cognition fields are the executor tokens streamed during the gap — what
// the round's thinking actually bought.
type gapInfo struct {
	ms                                    int64
	tainted, planner, compaction, handoff bool
	reasonTok, complTok, promptTok        int64
}

// toolBatch accumulates one round's top-level calls between model gaps.
type toolBatch struct {
	dispatchTS map[string]int64
	infos      map[string]*roundCall
	names      []string
	calls      int
	results    int
	readOnly   int
	serialMs   int64
	intervals  [][2]int64
}

// renderTimeAttribution aggregates recorded runs into one report line; empty
// when no run in the suite carried a trajectory.
func renderTimeAttribution(results []result) string {
	var toolMs, modelMs, gapMs, savedMs, delayP95, recoveryGapMs, cleanP95 int64
	var retryWaitMs, compactionMs, plannerMs, modelStreamMs, agentOtherMs, startupMs int64
	runs, rounds, batches, calls, singleReads, parallelBatches := 0, 0, 0, 0, 0, 0
	recoveryRounds, streamRetries, headerRetries, replays, emptyFinals := 0, 0, 0, 0, 0
	for _, r := range results {
		if r.Trajectory != nil {
			runs++
			toolMs += r.Trajectory.toolWall()
			modelMs += r.Trajectory.ModelMs
			rounds += r.Trajectory.ModelRounds
			gapMs += r.Trajectory.ModelGapTotalMs
			batches += r.Trajectory.ToolBatches
			calls += r.Trajectory.TopLevelCalls
			singleReads += r.Trajectory.SingleReadRounds
			parallelBatches += r.Trajectory.ParallelBatches
			savedMs += r.Trajectory.ParallelSavedMs
			delayP95 = max(delayP95, r.Trajectory.StartDelayP95Ms)
			recoveryRounds += r.Trajectory.RecoveryRounds
			recoveryGapMs += r.Trajectory.RecoveryGapMs
			cleanP95 = max(cleanP95, r.Trajectory.CleanGapP95Ms)
			streamRetries += r.Trajectory.StreamRetries
			headerRetries += r.Trajectory.HeaderRetries
			replays += r.Trajectory.ReasoningReplays
			emptyFinals += r.Trajectory.EmptyFinalRetries
			retryWaitMs += r.Trajectory.RetryWaitMs
			compactionMs += r.Trajectory.CompactionMs
			plannerMs += r.Trajectory.PlannerStreamMs
			modelStreamMs += r.Trajectory.ModelStreamMs
			agentOtherMs += r.Trajectory.AgentOtherMs
			if r.WallMs > r.Trajectory.SpanMs {
				startupMs += r.WallMs - r.Trajectory.SpanMs
			}
		}
	}
	if runs == 0 {
		return ""
	}
	line := fmt.Sprintf("**Time attribution** (%d recorded runs): **tools** %s (%s) · **model** %s (%s)",
		runs, dur(toolMs), pct(int(toolMs), int(toolMs+modelMs)),
		dur(modelMs), pct(int(modelMs), int(toolMs+modelMs)))
	if rounds > 0 {
		line += fmt.Sprintf(" · **model rounds** %d (avg gap %s)", rounds, dur(gapMs/int64(rounds)))
	}
	if batches > 0 {
		line += fmt.Sprintf("\n\n**Batching** (%d tool rounds): **calls/round** %.1f · **single-read rounds** %d (%s) · **parallel rounds** %d (saved %s) · **start-delay p95** %s",
			batches, float64(calls)/float64(batches),
			singleReads, pct(singleReads, batches),
			parallelBatches, dur(savedMs), durMs(delayP95))
	}
	if recoveryRounds+streamRetries+headerRetries+replays+emptyFinals > 0 {
		line += fmt.Sprintf("\n\n**Recovery**: recovery rounds %d (%s of rounds, %s) · stream retries %d · header retries %d · reasoning replays %d · empty-final retries %d · clean gap p95 %s",
			recoveryRounds, pct(recoveryRounds, rounds), dur(recoveryGapMs),
			streamRetries, headerRetries, replays, emptyFinals, durMs(cleanP95))
	}
	if plannerMs+modelStreamMs > 0 {
		line += fmt.Sprintf("\n\n**Wall decomposition**: **startup** %s · **agent** %s · **planner** %s · **model** %s · **tools** %s · **retry** %s · **compaction** %s",
			dur(startupMs), dur(agentOtherMs), dur(plannerMs), dur(modelStreamMs),
			dur(toolMs), dur(retryWaitMs), dur(compactionMs))
	}
	line += renderRoundEfficiency(results)
	return line + "\n\n"
}

// summarizeTrajectory reads a run's JSONL trajectory. A truncated final line
// (killed run) is skipped, matching the recorder's durability contract.
func summarizeTrajectory(path string) (*trajectorySummary, error) {
	scan, err := scanTrajectoryFile(path)
	if err != nil {
		return nil, err
	}
	return scan.finish(), nil
}

// scanTrajectoryFile runs the record pass without finishing, so callers that
// need the raw series (the live dashboard) can read it before finish folds it.
func scanTrajectoryFile(path string) (*trajScan, error) {
	f, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	defer f.Close()

	scan := &trajScan{
		s:                &trajectorySummary{Path: path},
		batch:            newToolBatch(),
		attemptBegin:     map[string]int64{},
		lastAttempt:      -1,
		seen:             map[string]bool{},
		denyDelegations:  map[string]bool{},
		delegationToolMs: map[string]int64{},
	}
	sc := bufio.NewScanner(f)
	sc.Buffer(make([]byte, 0, 1<<20), 16<<20)
	for sc.Scan() {
		var rec trajectoryRecord
		if err := json.Unmarshal(sc.Bytes(), &rec); err != nil {
			continue
		}
		scan.record(rec)
	}
	if err := sc.Err(); err != nil {
		return nil, err
	}
	return scan, nil
}

func (t *trajScan) record(rec trajectoryRecord) {
	t.s.Records++
	if t.firstTS == 0 {
		t.firstTS = rec.TS
		t.gapStart = rec.TS
		t.inModel = true
	}
	t.lastTS = rec.TS
	if rec.ProtocolRecovery == "missing_reasoning_retry_attempted" {
		t.s.ReasoningReplays++
		t.taintAs("reasoning_replay")
	}
	if cs := rec.ContractShadow; cs != nil {
		t.s.ShadowIntent = cs.Intent
		t.s.ShadowVerdict = cs.Verdict
		t.s.ShadowComplete = cs.Complete
	}
	if cr := rec.CompletionReport; cr != nil {
		t.s.CompletionVerdict = cr.Verdict
		t.s.CompletionGaps = cr.Gaps
		t.s.CompletionGapKinds = cr.GapKinds
		t.s.ClaimsVerified = cr.ClaimsVerified
		t.s.ClaimsUnbacked = cr.ClaimsUnbacked
	}
	if op := rec.OutcomeProgress; op != nil {
		t.outcomePoints = append(t.outcomePoints, outcomePoint{
			ts: rec.TS, round: op.Round, exploration: op.Exploration, verification: op.Verification,
			objective: op.Objective, regression: op.Regression, churn: op.Churn,
			legacyGain: op.LegacyGain, discriminating: op.Discriminating, debtAge: op.DebtAge,
			blindMutations: op.BlindMutations, ebmEligible: op.EBMEligible, ebmFired: op.EBMFired,
			governorEligible: op.GovernorEligible, governorEngaged: op.GovernorEngaged,
			runway: op.Runway, runwayDry: op.RunwayDry, runwayIdle: op.RunwayIdle, runwaySpent: op.RunwaySpent,
		})
	}
	if aa := rec.AnchorSafetyAudit; aa != nil {
		t.recordAnchorSafetyAudit(*aa)
	}
	if da := rec.DelegationAdmission; da != nil {
		t.s.DelegationCalls++
		if da.Verdict == "deny" {
			t.s.DelegationDenies++
			t.denyDelegations[da.Tool] = true
		}
	}
	if rec.Event == nil {
		return
	}
	switch rec.Event.Kind {
	case "retrying":
		t.s.Retries++
		t.pendingRetry = rec.TS
		switch rec.Event.RetryScope {
		case "stream":
			t.s.StreamRetries++
			t.taintAs("stream_retry")
		case "headers":
			t.s.HeaderRetries++
			t.taintAs("header_retry")
		default:
			t.taintAs("provider_retry")
		}
	case "notice":
		switch rec.Event.Code {
		case "empty_final":
			t.s.EmptyFinalRetries++
			t.taintAs("empty_final_retry")
		case "executor_handoff":
			t.s.HandoffNudges++
			t.gapHandoff = true
		case "progress_guard":
			t.s.NoProgressSignals++
		}
	case "reasoning", "text":
		if t.firstDelta == 0 {
			t.firstDelta = rec.TS
		}
	case "stream_attempt", "usage":
		t.recordModelPhase(rec)
	case "compaction_started":
		t.s.Compactions++
		t.compFrom = rec.TS
		t.gapCompact = true
	case "compaction_done":
		if t.compFrom > 0 && rec.TS > t.compFrom {
			t.compIvs = append(t.compIvs, [2]int64{t.compFrom, rec.TS})
		}
		t.compFrom = 0
	}
	if rec.Event.Tool == nil || rec.Event.Tool.ParentID != "" {
		// Subagent calls overlap the parent's wall clock; counting them
		// would double-book the span and split the parent's rounds.
		return
	}
	switch rec.Event.Kind {
	case "tool_dispatch":
		t.recordDispatch(rec)
	case "tool_result":
		t.recordResult(rec)
	}
}

// closeGap ends one model round; recovery-tainted rounds are booked apart so
// clean latency stays comparable across providers with different flake rates.
// The gap is queued until its batch closes and can classify the round.
func (t *trajScan) closeGap(gap int64) {
	t.gaps = append(t.gaps, gap)
	t.pendingGaps = append(t.pendingGaps, gapInfo{
		ms: gap, tainted: t.taint != "",
		planner: t.gapPlanner, compaction: t.gapCompact, handoff: t.gapHandoff,
		reasonTok: t.gapReason, complTok: t.gapCompl, promptTok: t.gapPrompt,
	})
	t.gapPlanner, t.gapCompact, t.gapHandoff = false, false, false
	t.gapReason, t.gapCompl, t.gapPrompt = 0, 0, 0
	if t.taint != "" {
		t.s.RecoveryRounds++
		t.s.RecoveryGapMs += gap
		if t.s.RecoveryGapMsByKind == nil {
			t.s.RecoveryGapMsByKind = map[string]int64{}
		}
		t.s.RecoveryGapMsByKind[t.taint] += gap
		t.taint = ""
		return
	}
	t.cleanGaps = append(t.cleanGaps, gap)
}

// taintAs marks the current gap as recovery; the first mechanism to fire in
// a gap owns its time, so per-kind splits stay disjoint.
func (t *trajScan) taintAs(kind string) {
	if t.taint == "" {
		t.taint = kind
	}
}

// recordModelPhase brackets sampling attempts (begin → commit/discard) and
// tags the just-closed attempt with its usage source. Subagent usage is
// skipped: subagent attempts never reach the parent sink, so a subagent usage
// arriving mid-parent-round must not claim the parent's attempt.
func (t *trajScan) recordModelPhase(rec trajectoryRecord) {
	if sa := rec.Event.StreamAttempt; sa != nil {
		switch sa.Action {
		case "begin":
			t.attemptBegin[sa.ID] = rec.TS
			if t.pendingRetry > 0 && rec.TS > t.pendingRetry {
				t.retryIvs = append(t.retryIvs, [2]int64{t.pendingRetry, rec.TS})
			}
			t.pendingRetry = 0
		case "commit", "discard":
			if begin, ok := t.attemptBegin[sa.ID]; ok && rec.TS > begin {
				t.attempts = append(t.attempts, modelAttempt{iv: [2]int64{begin, rec.TS}})
				t.lastAttempt = len(t.attempts) - 1
			}
			delete(t.attemptBegin, sa.ID)
		}
		return
	}
	if u := rec.Event.Usage; u != nil {
		source := u.Source
		if source == "" {
			source = "executor"
		}
		if t.s.RequestsBySource == nil {
			t.s.RequestsBySource = map[string]int{}
		}
		t.s.RequestsBySource[source]++
		switch source {
		case "planner":
			t.s.PlannerRequests++
			t.gapPlanner = true
		case "executor":
			t.s.ExecutorRequests++
			t.s.ReasoningTokensTotal += u.ReasoningTokens
			t.s.CompletionTokensTotal += u.CompletionTokens
			t.gapReason += u.ReasoningTokens
			t.gapCompl += u.CompletionTokens
			t.gapPrompt = max(t.gapPrompt, u.PromptTokens)
		case "subagent":
			t.s.SubagentRequests++
			return
		default:
			// Sidecar calls (goal-evaluator, compaction, capability-router)
			// have their own prompt shape; keep them out of the executor's
			// schema-tax and first-request accounting.
			return
		}
		if t.s.PromptTokensSeen == 0 && u.PromptTokens > 0 {
			t.s.FirstReqCacheHitTokens = u.CacheHitTokens
			t.s.FirstReqCacheMissTokens = u.CacheMissTokens
		}
		t.s.PromptTokensSeen += u.PromptTokens
		if d := u.CacheDiagnostics; d != nil {
			t.s.SchemaTokensTotal += d.ToolSchemaTokens
			t.s.SchemaTokensMax = max(t.s.SchemaTokensMax, d.ToolSchemaTokens)
			if d.PrefixChanged {
				t.s.PrefixResets++
			}
		}
		if t.lastAttempt >= 0 {
			t.attempts[t.lastAttempt].planner = u.Source == "planner"
			t.lastAttempt = -1
		}
	}
}

func (t *trajScan) recordDispatch(rec trajectoryRecord) {
	tl := rec.Event.Tool
	if t.inModel {
		t.closeGap(rec.TS - t.gapStart)
		t.inModel = false
		t.closeBatch()
	}
	// Refreshed dispatches re-announce a call already counted;
	// id-less records (older recordings) cannot be deduped.
	if tl.Refreshed {
		return
	}
	if tl.ID == "" || !t.batch.seen(tl.ID) {
		t.batch.calls++
	}
	// The full dispatch re-announces a streamed partial; keeping the later TS
	// anchors start-delay to pre-exec queueing, not the stream tail. The dup
	// check keys on the latest (fullest) name+args announcement.
	if tl.ID != "" {
		t.sawCallIDs = true
		t.batch.dispatchTS[tl.ID] = rec.TS
		key := tl.Name + "\x00" + tl.Args
		info := t.batch.infos[tl.ID]
		if info == nil {
			info = &roundCall{}
			t.batch.infos[tl.ID] = info
			t.batch.names = append(t.batch.names, tl.Name)
			if tl.Name == "connect_tool_source" {
				t.s.ConnectCalls++
			}
		}
		info.name = tl.Name
		info.dup = t.seen[key]
		t.seen[key] = true
	}
}

func (t *trajScan) recordResult(rec trajectoryRecord) {
	tl := rec.Event.Tool
	t.s.ToolMs += tl.DurationMs
	t.batch.results++
	if tl.ReadOnly {
		t.batch.readOnly++
	}
	if info, ok := t.batch.infos[tl.ID]; ok {
		info.resolved = true
		info.readOnly = tl.ReadOnly
		info.errored = tl.Err != ""
		if tl.Execution != nil {
			info.verification = tl.Execution.Verification
		}
	}
	if ex := tl.Execution; ex != nil && (ex.Verification == "passed" || ex.Verification == "failed") {
		t.observeVerification(tl.Name+"\x00"+tl.Args, ex.Verification == "passed", rec.TS)
	}
	if delegationTools[tl.Name] {
		t.delegationToolMs[tl.Name] += tl.DurationMs
	}
	t.batch.serialMs += tl.DurationMs
	if tl.StartedAt > 0 && tl.EndedAt >= tl.StartedAt {
		t.batch.intervals = append(t.batch.intervals, [2]int64{tl.StartedAt, tl.EndedAt})
		if t.firstToolTS == 0 || tl.StartedAt < t.firstToolTS {
			t.firstToolTS = tl.StartedAt
		}
		if disp, ok := t.batch.dispatchTS[tl.ID]; ok && tl.StartedAt >= disp {
			t.delays = append(t.delays, tl.StartedAt-disp)
		}
	} else {
		t.orphanMs += tl.DurationMs
	}
	t.gapStart = rec.TS
	t.inModel = true
}

func (t *trajScan) closeBatch() {
	b, s := t.batch, t.s
	if b.calls == 0 {
		return
	}
	if len(t.pendingGaps) > 0 {
		gap := t.pendingGaps[0]
		t.pendingGaps = t.pendingGaps[1:]
		if len(b.infos) > 0 {
			t.recordRound(classifyRound(gap, b), gap, b)
		}
	}
	s.ToolBatches++
	s.TopLevelCalls += b.calls
	s.MaxBatchSize = max(s.MaxBatchSize, b.calls)
	if b.calls == 1 && b.results == 1 && b.readOnly == 1 {
		s.SingleReadRounds++
		t.streakRun++
		s.SingleReadStreak = max(s.SingleReadStreak, t.streakRun)
	} else {
		t.streakRun = 0
	}
	if len(b.intervals) > 1 {
		wall, overlapped := intervalSpan(b.intervals)
		if overlapped {
			s.ParallelBatches++
		}
		if saved := b.serialMs - wall; saved > 0 {
			s.ParallelSavedMs += saved
		}
	}
	t.allIntervals = append(t.allIntervals, b.intervals...)
	t.batch = newToolBatch()
}

func (t *trajScan) finish() *trajectorySummary {
	s := t.s
	if t.inModel && t.lastTS > t.gapStart {
		t.closeGap(t.lastTS - t.gapStart) // final answer round
	}
	t.closeBatch()
	if t.sawCallIDs {
		for _, gap := range t.pendingGaps {
			t.recordRound(classifyRound(gap, nil), gap, nil)
		}
	}
	t.pendingGaps = nil
	s.ModelRounds = len(t.gaps)
	for _, g := range t.gaps {
		s.ModelGapTotalMs += g
	}
	s.ModelGapP95Ms = p95(t.gaps)
	s.CleanGapP95Ms = p95(t.cleanGaps)
	s.StartDelayP95Ms = p95(t.delays)
	for _, d := range t.delays {
		s.ToolQueueMs += d
	}
	if t.firstDelta > t.firstTS {
		s.TTFTMs = t.firstDelta - t.firstTS
	}
	if t.firstToolTS > t.firstTS {
		s.FirstToolMs = t.firstToolTS - t.firstTS
	}
	if len(t.allIntervals) > 0 {
		s.ToolWallMs = intervalUnion(t.allIntervals) + t.orphanMs
	}
	s.SpanMs = t.lastTS - t.firstTS
	if s.ModelMs = s.SpanMs - s.toolWall(); s.ModelMs < 0 {
		s.ModelMs = 0
	}
	s.Outcome = t.summarizeOutcome()
	// The admission verdict lands after the tool's result in the stream, so
	// denied time joins by tool name once the whole file is folded.
	for name := range t.denyDelegations {
		s.DeniedDelegationMs += t.delegationToolMs[name]
	}
	t.decompose()
	return s
}

// decompose partitions the span into disjoint wall buckets by priority, so a
// second spent in two places is booked once, to the more specific bucket.
func (t *trajScan) decompose() {
	if len(t.attempts) == 0 {
		return // old recording without stream_attempt events
	}
	s := t.s
	var planIvs, execIvs [][2]int64
	for _, a := range t.attempts {
		if a.planner {
			planIvs = append(planIvs, a.iv)
		} else {
			execIvs = append(execIvs, a.iv)
		}
	}
	covered := mergeIntervals(t.allIntervals)
	retry := clipIntervals(t.retryIvs, covered)
	covered = mergeIntervals(append(covered, retry...))
	comp := clipIntervals(t.compIvs, covered)
	covered = mergeIntervals(append(covered, comp...))
	plan := clipIntervals(planIvs, covered)
	covered = mergeIntervals(append(covered, plan...))
	exec := clipIntervals(execIvs, covered)
	s.RetryWaitMs = ivsLen(retry)
	s.CompactionMs = ivsLen(comp)
	s.PlannerStreamMs = ivsLen(plan)
	s.ModelStreamMs = ivsLen(exec)
	rem := s.SpanMs - s.toolWall() - s.RetryWaitMs - s.CompactionMs - s.PlannerStreamMs - s.ModelStreamMs
	if rem > 0 {
		s.AgentOtherMs = rem
	}
}

func newToolBatch() *toolBatch {
	return &toolBatch{dispatchTS: map[string]int64{}, infos: map[string]*roundCall{}}
}

func (b *toolBatch) seen(id string) bool {
	_, ok := b.dispatchTS[id]
	return ok
}

// durMs renders small durations without the sub-second floor dur applies.
func durMs(ms int64) string {
	if ms <= 0 {
		return "0ms"
	}
	if ms < 1000 {
		return fmt.Sprintf("%dms", ms)
	}
	return dur(ms)
}

func p95(values []int64) int64 {
	return pctile(values, 95)
}

func pctile(values []int64, p int) int64 {
	if len(values) == 0 {
		return 0
	}
	sorted := append([]int64(nil), values...)
	slices.Sort(sorted)
	index := min((len(sorted)*p+99)/100, len(sorted))
	return sorted[index-1]
}